CAT Scan: Abdomen (for Parents)

What It Is

An abdominal CAT scan is a painless test that uses a specialized X-ray machine to take pictures of a patient’s organs, blood vessels, and lymph nodes.

The doughnut-shaped machine circles the body, taking pictures to provide cross-sections of internal organs from various angles. These pictures are sent to a computer that records the images. It can also put them together to form a three-dimensional (3-D) image. A technician does the CAT scan (also called a CT scan or a computed axial tomography scan).

Why It’s Done

An abdominal CAT scan can detect signs of inflammation, infection, injury or disease of the liver, spleen, kidneys, bladder, stomach, intestines, pancreas, and adrenal glands. It is also used to look at blood vessels and lymph nodes in the abdomen. A doctor may order a CAT scan to find the cause of abdominal pain, diagnose an illness, or evaluate the effects of a traumatic injury.

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Preparation

Your child may be asked to remove all clothing and accessories and change into a hospital gown because buttons, zippers, clasps, or jewelry might interfere with the image.

Your child may have to avoid eating and drinking anything for a few hours before the scan to make sure that the stomach is empty. Fasting is required if your child will be sedated or needs to receive a contrast solution, which highlights certain parts of the body so doctors can see more detail in specific areas of the CAT scan.

If your daughter is pregnant, it’s important to tell the technician or doctor because there’s a small chance that the radiation from the CAT scan may harm the developing baby. But if the CAT scan is necessary, precautions can be taken to protect the baby.

Procedure

Procedure times vary, from several minutes to 45 minutes. The time depends on the age of the child, whether contrast solution is given, and whether sedation is needed. The actual exposure time to radiation is much less.

Your child will enter a special room and lie down on a narrow table. An abdominal CAT scan is performed with your child lying on his or her back, side, or stomach.

If contrast solution is required, it may be given through an intravenous line (IV) that will be placed in your child’s hand or arm. Placing the IV will feel like a quick pinprick, but the solution is painless as it goes into the vein. Otherwise, your child may be given oral contrast, which is a special fluid to drink before the procedure. Some kids don’t like the taste, but it can be flavored to make it more appealing.

The technician will position your child, then step behind a wall or into an adjoining room to operate the machine, viewing your child through a window. The technician will speak to your child through an intercom. You’ll be able to stay in the CAT scan room until the test begins, then you’ll join the technician in the outer room or you might be asked to sit in a waiting room. If you stay with the technician, you’ll be asked to wear a lead apron to protect certain parts of your body.

Sedation may be required if your child can’t lie still for the scan, which is common among infants and young kids. Sedation medicines are given through an IV line and help to keep a child comfortable during the CAT scan.

When the procedure begins, the table moves through the CAT machine. Older kids will be asked to hold their breath and stay still for a few seconds at a time to prevent the images from being blurred.

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What to Expect

Your child won’t feel anything as the CAT scan is taken, but may hear whirring and buzzing sounds as the machine works. The room may feel cool due to air conditioning used to maintain the equipment. Some kids may feel uncomfortable lying still for extended periods.

After the scan is complete, your child will be asked to wait a few minutes so the technician can review the quality of the images. If they’re blurred, parts of the CAT scan may need to be redone. If your child required sedation, it will take a little while for the medicine to wear off.

Getting the Results

The CAT scan images will be looked at by a radiologist (a doctor who is specially trained in reading and interpreting X-ray images). The radiologist will send a report to your child’s doctor, who will discuss the results with you and explain what they mean.

Results are usually ready in 1-2 days. If the CAT scan was done on an emergency basis, the results can be made available quickly. In most cases, results can’t be given directly to the patient or family at the time of the test.

Risks

In general, CAT scans are very safe although more radiation is required than in a regular X-ray. Any exposure to radiation poses some risk to the body, but the amount used in an individual CAT scan procedure isn’t considered dangerous. It’s important to know that radiologists use the minimum amount of radiation required to get the best results.

If your daughter is pregnant, there’s a risk of harm to the developing baby, so precautions must be taken.

Contrast solutions are generally safe, with a very low incidence of allergic reactions. They may contain iodine, which might cause problems for kids with an iodine or shellfish allergy, and some other illnesses. Make sure to tell your doctor about any medication, dye, and food allergies that your child may have. Some patients who are at risk for an allergic reaction to the contrast solution may need medications like antihistamines or steroids to minimize the risk of a reaction.

If your child needs sedation, there’s a slight chance of slowed breathing due to the medications. If there are any problems with the sedation, the CAT scan staff is prepared to treat them right away.

Helping Your Child

You can help your child prepare for a CAT scan by explaining the test in simple terms before the procedure. You can describe the room and the equipment that will be used, and reassure your child that you’ll be close by. For older kids, be sure to explain the importance of keeping still so the scan can be completed quickly and parts of it don’t have to be repeated.

If You Have Questions

If you have questions about why the abdominal CAT scan is needed, speak with the doctor. You can also talk to the CAT scan technician before the procedure.

Imaging Inflammation and Infection in the Gastrointestinal Tract

3.1. Diverticulitis

Diverticulitis is characterized by the presence of inflamed diverticula in the GI tract, most commonly the large intestine. Sixty-five percent of the elderly population and 5% of individuals 40 years old or younger will have diverticula, 25% of those individuals will have diverticulitis while the remaining are asymptomatic [74,75]. Symptomatic diverticulitis is frequently coupled with complications including anal bleeding, fistulas, perforation, and abscess formation [74,76,77,78]. The clinical misdiagnosis rate of diverticulitis is upwards of 50%, indicating the need for better diagnostic techniques [79]. Recently there has been a spark in the investigation of potential biomarkers as safe and effective ways to diagnosis and assist physicians in treating diverticulitis [74]. C-reactive protein levels >50 mg/L, in addition to left lower quadrant abdominal tenderness and absences of vomiting is indicative of diverticulitis [79,80]. Fecal calprotectin is derived from neutrophils, so its presence in the stool is a good indication of inflammation in the GI tract. A study done by Tursi et al. showed increased levels of fecal calprotectin concentrations in diverticulitis patients when compared to IBS and control patients [81]. This provides an appealing clinical tool for differentiation between IBS and diverticulitis, although it must be noted that IBS and diverticulitis can exist simultaneously. Increased levels of these biomarkers in the blood and stool strongly support a clinical diagnosis of diverticulitis but are not specific enough to fully replace initial imaging techniques.

3.1.1. X-ray

Contrast enemas have been used in an attempt to diagnose cases of diverticulitis [82,83]. Initially, barium had been used as the contrast agent, but the shift to water soluble contrast agents was made to minimize risk to the patient. Water soluble contrast agents eliminated the risk of barium peritonitis, decreased the wait time between injection and scan, and allowed for other imaging modalities to be utilized after the enema [76,84,85]. While water-soluble contrast enemas are extremely beneficial at showing morphological changes of the colon, they are limited in that they cannot indicate active inflammation which is a key marker of diverticulitis. Therefore, the enema is then incapable of making a complete diagnosis of diverticulitis without the assistance of another imaging modality or it may result in a misdiagnosis indicating a low sensitivity of contrast enemas () [86].

3.1.2. Computed Tomography

Computed tomography (CT) has many advantages when compared to the traditional contrast enema, which is why it is now accepted as the primary imaging modality for patients that present with abdominal pain. A CT scan will identify inflamed diverticula, bowel wall inflammation, pericolic fat stranding, and corresponding complications [9,10,11,83,87,88]. CT is capable of visualizing pericolonic and colonic complications which results in a more accurate diagnosis for the patient, along with better standard of care. Thirty percent of cases of diverticulitis are accompanied by complications including, fistulas, perforations, and abscesses. Accurate assessment of complications is crucial in the development of a treatment plan. CT is particularly beneficial in the management of abscesses since it can be used for percutaneous drainage of the abscesses. Such drainage eliminates the need for multiple surgeries, making CT more cost effective and lower risk for the patients [9,10,77,82,83,86,88,89,90,91].

Contrast agents are utilized in CT scans to achieve maximum colonic distension along with colonic opacification in order to better identify inflammatory wall thickening consistent with diverticulitis [90]. Opacification of the colon is necessary to differentiate between intra and extra luminal air and fluid cavities, indicating the presence of abscesses [11,90,92]. Oral contrast agents are beneficial to the visualization of loops within the small bowel, but lack in completely covering the colon. Oral contrast agents are limited by inconsistent opacification of the colon and a large waiting period, resulting in the infrequent use of these types of agents [11,92]. Intravenous contrast agents are advantageous due to their capability of enhancing inflammation in the abdominal and pelvic regions. Such enhancement permits a more accurate identification of other illnesses that may have similar clinical symptoms as diverticulitis [83,87]. The use of an intravenous contrast agent is associated with a higher risk to the patient, at no significant benefit in comparison to rectally administered contrast agents [11,92]. Rectally administered contrast agents are the safest and most efficient way of obtaining uniform opacification of the colon with maximum distention [90]. Gastrografin-based contrast agents are the most widely used agents when imaging the gastrointestinal tract [9,11]. The risks associated with rectal contrast agents are similar to those associated with performing an enema: there is a higher chance of exacerbating perforations or extravasation of contrast material [92].

3.1.3. Ultrasonography

Ultrasonography (US) is an extremely low cost and low risk imaging modality that is not frequently used for the diagnosis of diverticulitis due to its reliance on a technician and inferiority to CT. While ultrasound is non-invasive, provides real-time images, and is useful in identifying inflammation, abscesses, and bowel wall thickening, it is limited in that it cannot be used on obese patients and that is can be impeded by gas bubbles [77,87]. A meta-analysis of 6 CT studies and 6 US studies showed that CT was no better or worse than ultrasound at diagnosing diverticulitis (), but CT still remains the modality of choice due to its ability to detect a multitude of complications [12,77,91].

3.1.4. Magnetic Resonance Imaging

While magnetic resonance imaging (MRI) is not traditionally used when a patient presents with abdominal pain, it has proven to have a high sensitivity and specificity in the diagnosis of diverticulitis, especially with the introduction of an intravenous gadolinium-based contrast agent () [14,15,87]. MRI is superior to CT in that it lacks associated harmful ionizing radiation, thus an appealing and a safe alternative to CT, but gadolinium-based contrast agents remain somewhat controversial with potential Gadolinium toxicity [93,94]. However, the use of MRI in diagnosing diverticulitis is limited not only by its cost and time, but also by the motion of other organs to continue breathing while the scan is taking place [14]. Due to these obstacles, MRI remains in the shadow of other imaging modalities for diagnosis of diverticulitis.

3.1.5. Endoscopy

Many features that are indicative of a CT scan are also indicators of colorectal cancer. After a positive diagnosis is made using CT, it is standard procedure for the patient to get a follow up colonoscopy around 6 weeks after being diagnosed [9,95]. This is a preventative measure to ensure that the diagnosis of diverticulitis did not miss a diagnosis of colon cancer [77,82,87,91,95,96,97]. In a study conducted by Lau et al. , 34% of patients’ follow up colonoscopies came back positive for further complications or misdiagnosis of the initial diverticulitis [97]. While there is nothing to indicate that a positive diagnosis for diverticulitis is correlated with a higher risk for colorectal cancer, it has been observed that patients who present with diverticular complications have been more likely to have a positive colonoscopy for colorectal cancer sometime after the diverticulitis diagnosis [77,97].

3.2. Irritable Bowel Disease

Irritable bowel disease (IBD) is expressed in two major forms: Crohn’s disease (CD) and ulcerative colitis (UC). For both manifestations, IBD symptoms are similar to those of other GI disorders and include abdominal pain or discomfort, weight loss, bloody stool, diarrhea, and nausea [98]. In the intestines, the small and large bowel walls thicken and abscesses, collections of fluid surrounded in the inflamed intestinal tissue, may form. Unlike other disorders, the intensity of IBD symptoms changes with time. Periods of high intensity symptoms are defined as “flare,” while times of low intensity symptoms indicate “remission” [99].

Incidence of IBD in the United States and Europe is increasing, with current estimates of the affected population in those countries exceeding 1.6 million and 3 million, respectively [99,100,101,102]. For the different manifestations of IBD, CD’s prevalence in children and adults is 58 and 241 cases per 100,000, respectively, while UC prevalence in children and adults is 34 and 263 cases per 100,000, respectively [102,103,104]. In the United States, CD incidence is currently estimated to be 3.1–14.6 cases per 100,000 person-years and UC incidence is estimated at 2.2–14.3 cases per 100,000 person-years [102,103]. IBD occurrence is spreading across the world as well, with observed incidences in developing countries [100]. Approximately 20% of IBD patients are diagnosed during their childhood [99,104]. The effects of IBD have long-term impacts on children, namely growth failure or delays in puberty onset [63,100]. In 10–15% of IBD cases, CD and UC cannot be distinguished based on how they present in the patient, who is given an “IBD-unclassified” diagnosis. IBD patients are also at an increased risk of developing colorectal cancer, primarily due to the chronic intestinal inflammation inherent to CD and UC [105,106]. Eaden et al., in their meta-analysis, showed that patients with UC developed a cumulative risk to develop colorectal cancer of 2%, 8%, and 18% at 10, 20, and 30 years, respectively, after disease development [105,106,107]. Another study by Beaugerie and Itzkowitz demonstrated that in North America and some countries in Europe, the risk of colorectal cancer in IBD patients is up to two times higher than the risk of the general public [108].

The need for rapid and accurate imaging of IBD and its manifestations is apparent given its increasing prevalence and worldwide impact. Various imaging methods are practiced for IBD identification and monitoring [99]. with potential new and more effective modalities entering the clinical landscape as time progresses.

3.2.1. Endoscopy

Endoscopy is usually among the first steps carried out in diagnosing IBD [109,110,111]. The most common endoscopic technique is colonoscopy. In this procedure, clinicians insert an endoscope, comprised of a white light and a camera, into the patient via the anus for direct visualization of the colon. Colonoscopy is a highly invasive procedure, proving undesirable for patients. Other endoscopic techniques that offer minimal invasion are practiced, such as single-balloon and double-balloon enteroscopy [111].

3.2.2. Chromoendoscopy

To improve the surveillance of dysplasia, lesions, and other abnormalities in mucosal topography, chromoendoscopy (CE) may be used [112,113,114]. In this technique, dilute dye (indigo carmine or methylene blue) is sprayed, within appropriate guidelines, onto the lumen of the colon using a dye spray catheter [113]. This dye better reveals the location and pattern of lesions present in the colon, aiding clinician analysis, biopsy, or removal of present tissue. Compared to standard white light colonoscopy, CE has proved to be superior in multiple studies on per-patient and per-lesion analysis [113,114]. Given this, in order to increase accuracy of analysis and dysplasia detection, most international subspecialty societies recommend the use of CE when examining IBD patients [112]. This accuracy is particularly beneficial for early detection of colorectal cancer in patients.

3.2.3. Computed Tomography

Given its ease-of-access, non-invasive nature, ability to scan intraluminal and extraluminal effects, and not requiring anesthesia due to short scan times, computed tomography (CT) is a highly favorable method for IBD imaging [115]. The rapid image acquisition is particularly beneficial for pediatric patients, who may be more susceptible to the harmful effects of anesthesia. IBD evaluation via CT typically requires application of both oral and IV contrast agents, such as the gastrogafin-based agents described above [99,116,117]. These agents distend and opacify the bowel to reveal where extraluminal fluids are collected and to best characterize the abnormalities (e. g., thickening) in the bowel wall. To detect mucosal enhancement, associated with inflammation of or lesions in the intestines, CT enterography (CTE) may be used, which requires application of neutral contrast agents (e.g., water) [99,117]. Cross-sectional images of patients reveal the type and extent of their intestinal inflammation. The location and degree of inflammation and wall thickening determines the manifestation of IBD [118]. Further, these factors are heavily considered when diagnosing patients with IBD as opposed to other diseases. Specificity and sensitivity values for CT studies of IBD are shown in .

As stated, CT images can be acquired quickly and does not require use of anesthetics. Further, they are easy to reproduce and possess high spatial resolution, presenting clearer images to clinicians. These factors alone make it a strong modality for imaging IBD patients. CTE may boast greater sensitivity and specificity over magnetic resonance enterography (MRE) [99,119,120]. CT is not without its disadvantages. The greatest apparent drawback with CT usage is the required patient exposure to radiation [99,121,122]. Given the chronic nature of IBD, patients need frequent imaging for monitoring disease progress and symptom flare. Repeated exposure to ionizing radiation is not ideal, especially given the increased risk of cancer produced in patients. This is especially undesirable for pediatric patients, of which there is a significant number. Other studies have shown that CT imaging, when compared to US and MRI, may actually possess lower specificity and sensitivity for IBD diagnoses, decreasing its overall reliability [19,123]. Another potential disadvantage is that CT cannot be performed in patients who are allergic to contrast agents used.

It should be noted that the prevalence of CT usage, and thus associated regional clinician skill, is much higher in the United States as compared to Europe, where US and MRI are favored [19]. For all these modalities, this disparity can affect the specificity and sensitivity results when looking at a global as opposed to regional scale.

3.2.4. Positron Emission Tomography

For analysis of IBD, particularly in symptom flare situations or pediatric diagnostic work-ups, CT scanning is paired with positron emission tomography (PET) [21,123,124,125,126,127]. PET molecular imaging tracks accumulation of molecular radiopharmaceutical ¹⁸F-FDG to determine inflamed areas. ¹⁸F-FDG is used as it is similar to glucose and experiences significant uptake by leukocytes activated by tissue damage and inflammation. In pairing PET with CT, three-dimensional CT reconstructions follow PET molecular imaging to confirm anatomical and structural information in vivo [124]. Many studies have confirmed the usefulness of PET/CT imaging, particularly in cases where IBD affects the small bowel [123,128,129,130,131,132,133]. Further, PET/CT is reported to have better sensitivity than endoscopy, though a lower specificity than ultrasound [21,123,125]. More studies are recommended to better characterize the effectiveness of this joint modality [125,128]. An example of PET/CT imaging is shown in .

¹⁸F-FDG PET/CT scan of ulcerative colitis (UC) patient. Extent of disease is seen on the left and in areas indicated by arrows in the right panel [124].

3.2.5. Immuno-PET

A relatively new modality for IBD imaging is immuno-PET. Using fragments of monoclonal antibodies (mAbs), innate immune cells, especially present during symptom flare of IBD, are targeted to track inflammation [134,135]. While testing of this modality is primarily still in the preclinical stage, murine model results are promising for translation to clinical applications [134,135]. mAb-therapeutic response can be measured with this imaging method as well [136]. This modality may also be useful in characterizing cancers of the GI tract, such as colon cancer, given the specificity of mAb technologies [136].

3.2.6. Ultrasonography

Using sound waves, ultrasonography (US) provides real-time images of the body’s interior. For determining IBD presence and extent, bowel wall thickness is the primary factor considered with US modalities [99,137,138,139]. Given its non-invasive nature and ability to render images in real-time, US is heavily favored for IBD imaging and analysis. US modalities do not expose patients to any radiation, are widely available, and remain generally inexpensive [99,140]. Studied specificity and selectivity values for US usage in IBD cases can be seen in .

There are several drawbacks to US imaging for IBD. For one, US has been primarily used with CD patients, limiting its effectiveness for UC cases [137]. Further, one meta-analysis indicates US is used more in Europe than in the United States [19]. This indicates that the accuracy for US techniques, given clinician exposure and usage, may be lower in the United States in comparison to Europe. The time required and accuracy of the imaging are heavily dependent on the experience of the clinician and size of the patient.

3.2.7. Contrast-Enhanced US

Some IBD patients may still exhibit wall thickening without active inflammation [141,142,143,144]. In these cases, US could lead to inappropriate therapy for the patient as the symptom intensity misaligns with the proposed treatment. To increase the accuracy of US in these and general IBD cases, contrast enhanced ultrasonography (CEUS) may be used. CEUS uses a intravenously applied microbubble contrast agent, such as sulfur hexafluoride, to show bowel wall enhancement and mesentery [144,145]. CEUS provides real-time information on the vascularity of the scanned area. Since IBD causes vascular alterations in affected areas, this information gives clinicians an understanding on IBD activity in the patient [144,145,146,147,148]. In general, CEUS appears to provide greater clinical certainty in evaluating IBD in patients.

3.2.8. Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) produces three-dimensional anatomical images of patients. In imaging the GI tract, especially for small bowel analysis, MR enterography (MRE), MR enteroclysis, and MR fistulography are the commonly used procedures [99,149]. For both the small and large bowel, intra and extra mural involvement can be measured with the appropriate contrast agents such as barium suspensions [99,150]. These agents induce bowel wall distension, ensuring easier detection of bowel wall complications, and fat suppression for ease of image interpretation [99,150,151]. Fat stranding, wall thickening, and intestinal strictures are all evidence for IBD found in MRI analyses [99,152]. MRI techniques do not use ionizing radiation to acquire images, making them favorable over CT modalities, especially for young patients. Additionally, MRI produces high resolution images while permitting significantly improved soft tissue contrast as compared to CT [149].

As with previously analyzed modalities requiring contrast agents, MRI cannot be used with patients who are allergic to contrast agents. Additionally, the long scan time (compared to US, for example) is logistically inconvenient for patients, and may require sedation [99]. Further, reference information and clinician or technology-induced bias can lead to improper image assessment [19,119,143].

3.2.9. Multispectral Optoacoustic Tomography

By stimulating patient tissues with lasers, ultrasound waves are generated. These waves can be read and interpreted to understand tissue characteristics inside patients. This phenomenon is the basis for multispectral optoacoustic tomography (MSOT) technologies. MSOT is purely non-invasive in nature and allows for real-time imaging of patient tissue in vivo [66,153,154]. Images gathered by MSOT show the distribution of such molecules as hemoglobin and melanin in patient tissue, due to the difference in how these molecules absorb light [155]. This distribution is indicative of disease presence and behavior in patients. A study evaluating MSOT imaging of murine colitis showed the correlation between inflammation level and concentration of oxy-hemoglobin () [66]. In a separate study, clinical trials on CD patients have shown similar results: Increased oxy-hemoglobin levels with active CD compared to remission CD [153,156]. MSOT technologies are still undergoing clinical trials for widespread use and are primarily seen in Europe. Preliminary results reveal significant potential for MSOT in rapidly diagnosing and monitoring IBD.

Multispectral optoacoustic tomography (MSOT) (A–C) and colonoscopic (D–F) images of murine colitis progression. Images were taken at t = 0, 2, and 7 days after bacterial inoculation. Yellow arrows indicate areas of inflammation correlating with colitis [67].

In summary, inflammatory conditions such as diverticulitis and IBD can be diagnosed and analyzed by a wide range of imaging modalities. Further work is required to verify the accuracy and refine the safety or comfortability of some of the mentioned modalities. Emerging technologies such as immuno-PET and MSOT could prove increasingly beneficial to imaging and diagnostic accuracy while increasing patient compliance. Since inflammation is also consistent with infection, it is important for patients with diverticulitis and IBD to be regularly monitored for alternative infectious or malignant diseases.

Imaging Inflammation and Infection in the Gastrointestinal Tract

3.1. Diverticulitis

Diverticulitis is characterized by the presence of inflamed diverticula in the GI tract, most commonly the large intestine. Sixty-five percent of the elderly population and 5% of individuals 40 years old or younger will have diverticula, 25% of those individuals will have diverticulitis while the remaining are asymptomatic [74,75]. Symptomatic diverticulitis is frequently coupled with complications including anal bleeding, fistulas, perforation, and abscess formation [74,76,77,78]. The clinical misdiagnosis rate of diverticulitis is upwards of 50%, indicating the need for better diagnostic techniques [79]. Recently there has been a spark in the investigation of potential biomarkers as safe and effective ways to diagnosis and assist physicians in treating diverticulitis [74]. C-reactive protein levels >50 mg/L, in addition to left lower quadrant abdominal tenderness and absences of vomiting is indicative of diverticulitis [79,80]. Fecal calprotectin is derived from neutrophils, so its presence in the stool is a good indication of inflammation in the GI tract. A study done by Tursi et al. showed increased levels of fecal calprotectin concentrations in diverticulitis patients when compared to IBS and control patients [81]. This provides an appealing clinical tool for differentiation between IBS and diverticulitis, although it must be noted that IBS and diverticulitis can exist simultaneously. Increased levels of these biomarkers in the blood and stool strongly support a clinical diagnosis of diverticulitis but are not specific enough to fully replace initial imaging techniques.

3.1.1. X-ray

Contrast enemas have been used in an attempt to diagnose cases of diverticulitis [82,83]. Initially, barium had been used as the contrast agent, but the shift to water soluble contrast agents was made to minimize risk to the patient. Water soluble contrast agents eliminated the risk of barium peritonitis, decreased the wait time between injection and scan, and allowed for other imaging modalities to be utilized after the enema [76,84,85]. While water-soluble contrast enemas are extremely beneficial at showing morphological changes of the colon, they are limited in that they cannot indicate active inflammation which is a key marker of diverticulitis. Therefore, the enema is then incapable of making a complete diagnosis of diverticulitis without the assistance of another imaging modality or it may result in a misdiagnosis indicating a low sensitivity of contrast enemas () [86].

3.1.2. Computed Tomography

Computed tomography (CT) has many advantages when compared to the traditional contrast enema, which is why it is now accepted as the primary imaging modality for patients that present with abdominal pain. A CT scan will identify inflamed diverticula, bowel wall inflammation, pericolic fat stranding, and corresponding complications [9,10,11,83,87,88]. CT is capable of visualizing pericolonic and colonic complications which results in a more accurate diagnosis for the patient, along with better standard of care. Thirty percent of cases of diverticulitis are accompanied by complications including, fistulas, perforations, and abscesses. Accurate assessment of complications is crucial in the development of a treatment plan. CT is particularly beneficial in the management of abscesses since it can be used for percutaneous drainage of the abscesses. Such drainage eliminates the need for multiple surgeries, making CT more cost effective and lower risk for the patients [9,10,77,82,83,86,88,89,90,91].

Contrast agents are utilized in CT scans to achieve maximum colonic distension along with colonic opacification in order to better identify inflammatory wall thickening consistent with diverticulitis [90]. Opacification of the colon is necessary to differentiate between intra and extra luminal air and fluid cavities, indicating the presence of abscesses [11,90,92]. Oral contrast agents are beneficial to the visualization of loops within the small bowel, but lack in completely covering the colon. Oral contrast agents are limited by inconsistent opacification of the colon and a large waiting period, resulting in the infrequent use of these types of agents [11,92]. Intravenous contrast agents are advantageous due to their capability of enhancing inflammation in the abdominal and pelvic regions. Such enhancement permits a more accurate identification of other illnesses that may have similar clinical symptoms as diverticulitis [83,87]. The use of an intravenous contrast agent is associated with a higher risk to the patient, at no significant benefit in comparison to rectally administered contrast agents [11,92]. Rectally administered contrast agents are the safest and most efficient way of obtaining uniform opacification of the colon with maximum distention [90]. Gastrografin-based contrast agents are the most widely used agents when imaging the gastrointestinal tract [9,11]. The risks associated with rectal contrast agents are similar to those associated with performing an enema: there is a higher chance of exacerbating perforations or extravasation of contrast material [92].

3.1.3. Ultrasonography

Ultrasonography (US) is an extremely low cost and low risk imaging modality that is not frequently used for the diagnosis of diverticulitis due to its reliance on a technician and inferiority to CT. While ultrasound is non-invasive, provides real-time images, and is useful in identifying inflammation, abscesses, and bowel wall thickening, it is limited in that it cannot be used on obese patients and that is can be impeded by gas bubbles [77,87]. A meta-analysis of 6 CT studies and 6 US studies showed that CT was no better or worse than ultrasound at diagnosing diverticulitis (), but CT still remains the modality of choice due to its ability to detect a multitude of complications [12,77,91].

3.1.4. Magnetic Resonance Imaging

While magnetic resonance imaging (MRI) is not traditionally used when a patient presents with abdominal pain, it has proven to have a high sensitivity and specificity in the diagnosis of diverticulitis, especially with the introduction of an intravenous gadolinium-based contrast agent () [14,15,87]. MRI is superior to CT in that it lacks associated harmful ionizing radiation, thus an appealing and a safe alternative to CT, but gadolinium-based contrast agents remain somewhat controversial with potential Gadolinium toxicity [93,94]. However, the use of MRI in diagnosing diverticulitis is limited not only by its cost and time, but also by the motion of other organs to continue breathing while the scan is taking place [14]. Due to these obstacles, MRI remains in the shadow of other imaging modalities for diagnosis of diverticulitis.

3.1.5. Endoscopy

Many features that are indicative of a CT scan are also indicators of colorectal cancer. After a positive diagnosis is made using CT, it is standard procedure for the patient to get a follow up colonoscopy around 6 weeks after being diagnosed [9,95]. This is a preventative measure to ensure that the diagnosis of diverticulitis did not miss a diagnosis of colon cancer [77,82,87,91,95,96,97]. In a study conducted by Lau et al., 34% of patients’ follow up colonoscopies came back positive for further complications or misdiagnosis of the initial diverticulitis [97]. While there is nothing to indicate that a positive diagnosis for diverticulitis is correlated with a higher risk for colorectal cancer, it has been observed that patients who present with diverticular complications have been more likely to have a positive colonoscopy for colorectal cancer sometime after the diverticulitis diagnosis [77,97].

3.2. Irritable Bowel Disease

Irritable bowel disease (IBD) is expressed in two major forms: Crohn’s disease (CD) and ulcerative colitis (UC). For both manifestations, IBD symptoms are similar to those of other GI disorders and include abdominal pain or discomfort, weight loss, bloody stool, diarrhea, and nausea [98]. In the intestines, the small and large bowel walls thicken and abscesses, collections of fluid surrounded in the inflamed intestinal tissue, may form. Unlike other disorders, the intensity of IBD symptoms changes with time. Periods of high intensity symptoms are defined as “flare,” while times of low intensity symptoms indicate “remission” [99].

Incidence of IBD in the United States and Europe is increasing, with current estimates of the affected population in those countries exceeding 1.6 million and 3 million, respectively [99,100,101,102]. For the different manifestations of IBD, CD’s prevalence in children and adults is 58 and 241 cases per 100,000, respectively, while UC prevalence in children and adults is 34 and 263 cases per 100,000, respectively [102,103,104]. In the United States, CD incidence is currently estimated to be 3.1–14.6 cases per 100,000 person-years and UC incidence is estimated at 2.2–14.3 cases per 100,000 person-years [102,103]. IBD occurrence is spreading across the world as well, with observed incidences in developing countries [100]. Approximately 20% of IBD patients are diagnosed during their childhood [99,104]. The effects of IBD have long-term impacts on children, namely growth failure or delays in puberty onset [63,100]. In 10–15% of IBD cases, CD and UC cannot be distinguished based on how they present in the patient, who is given an “IBD-unclassified” diagnosis. IBD patients are also at an increased risk of developing colorectal cancer, primarily due to the chronic intestinal inflammation inherent to CD and UC [105,106]. Eaden et al., in their meta-analysis, showed that patients with UC developed a cumulative risk to develop colorectal cancer of 2%, 8%, and 18% at 10, 20, and 30 years, respectively, after disease development [105,106,107]. Another study by Beaugerie and Itzkowitz demonstrated that in North America and some countries in Europe, the risk of colorectal cancer in IBD patients is up to two times higher than the risk of the general public [108].

The need for rapid and accurate imaging of IBD and its manifestations is apparent given its increasing prevalence and worldwide impact. Various imaging methods are practiced for IBD identification and monitoring [99]. with potential new and more effective modalities entering the clinical landscape as time progresses.

3.2.1. Endoscopy

Endoscopy is usually among the first steps carried out in diagnosing IBD [109,110,111]. The most common endoscopic technique is colonoscopy. In this procedure, clinicians insert an endoscope, comprised of a white light and a camera, into the patient via the anus for direct visualization of the colon. Colonoscopy is a highly invasive procedure, proving undesirable for patients. Other endoscopic techniques that offer minimal invasion are practiced, such as single-balloon and double-balloon enteroscopy [111].

3.2.2. Chromoendoscopy

To improve the surveillance of dysplasia, lesions, and other abnormalities in mucosal topography, chromoendoscopy (CE) may be used [112,113,114]. In this technique, dilute dye (indigo carmine or methylene blue) is sprayed, within appropriate guidelines, onto the lumen of the colon using a dye spray catheter [113]. This dye better reveals the location and pattern of lesions present in the colon, aiding clinician analysis, biopsy, or removal of present tissue. Compared to standard white light colonoscopy, CE has proved to be superior in multiple studies on per-patient and per-lesion analysis [113,114]. Given this, in order to increase accuracy of analysis and dysplasia detection, most international subspecialty societies recommend the use of CE when examining IBD patients [112]. This accuracy is particularly beneficial for early detection of colorectal cancer in patients.

3.2.3. Computed Tomography

Given its ease-of-access, non-invasive nature, ability to scan intraluminal and extraluminal effects, and not requiring anesthesia due to short scan times, computed tomography (CT) is a highly favorable method for IBD imaging [115]. The rapid image acquisition is particularly beneficial for pediatric patients, who may be more susceptible to the harmful effects of anesthesia. IBD evaluation via CT typically requires application of both oral and IV contrast agents, such as the gastrogafin-based agents described above [99,116,117]. These agents distend and opacify the bowel to reveal where extraluminal fluids are collected and to best characterize the abnormalities (e.g., thickening) in the bowel wall. To detect mucosal enhancement, associated with inflammation of or lesions in the intestines, CT enterography (CTE) may be used, which requires application of neutral contrast agents (e.g., water) [99,117]. Cross-sectional images of patients reveal the type and extent of their intestinal inflammation. The location and degree of inflammation and wall thickening determines the manifestation of IBD [118]. Further, these factors are heavily considered when diagnosing patients with IBD as opposed to other diseases. Specificity and sensitivity values for CT studies of IBD are shown in .

As stated, CT images can be acquired quickly and does not require use of anesthetics. Further, they are easy to reproduce and possess high spatial resolution, presenting clearer images to clinicians. These factors alone make it a strong modality for imaging IBD patients. CTE may boast greater sensitivity and specificity over magnetic resonance enterography (MRE) [99,119,120]. CT is not without its disadvantages. The greatest apparent drawback with CT usage is the required patient exposure to radiation [99,121,122]. Given the chronic nature of IBD, patients need frequent imaging for monitoring disease progress and symptom flare. Repeated exposure to ionizing radiation is not ideal, especially given the increased risk of cancer produced in patients. This is especially undesirable for pediatric patients, of which there is a significant number. Other studies have shown that CT imaging, when compared to US and MRI, may actually possess lower specificity and sensitivity for IBD diagnoses, decreasing its overall reliability [19,123]. Another potential disadvantage is that CT cannot be performed in patients who are allergic to contrast agents used.

It should be noted that the prevalence of CT usage, and thus associated regional clinician skill, is much higher in the United States as compared to Europe, where US and MRI are favored [19]. For all these modalities, this disparity can affect the specificity and sensitivity results when looking at a global as opposed to regional scale.

3.2.4. Positron Emission Tomography

For analysis of IBD, particularly in symptom flare situations or pediatric diagnostic work-ups, CT scanning is paired with positron emission tomography (PET) [21,123,124,125,126,127]. PET molecular imaging tracks accumulation of molecular radiopharmaceutical ¹⁸F-FDG to determine inflamed areas. ¹⁸F-FDG is used as it is similar to glucose and experiences significant uptake by leukocytes activated by tissue damage and inflammation. In pairing PET with CT, three-dimensional CT reconstructions follow PET molecular imaging to confirm anatomical and structural information in vivo [124]. Many studies have confirmed the usefulness of PET/CT imaging, particularly in cases where IBD affects the small bowel [123,128,129,130,131,132,133]. Further, PET/CT is reported to have better sensitivity than endoscopy, though a lower specificity than ultrasound [21,123,125]. More studies are recommended to better characterize the effectiveness of this joint modality [125,128]. An example of PET/CT imaging is shown in .

¹⁸F-FDG PET/CT scan of ulcerative colitis (UC) patient. Extent of disease is seen on the left and in areas indicated by arrows in the right panel [124].

3.2.5. Immuno-PET

A relatively new modality for IBD imaging is immuno-PET. Using fragments of monoclonal antibodies (mAbs), innate immune cells, especially present during symptom flare of IBD, are targeted to track inflammation [134,135]. While testing of this modality is primarily still in the preclinical stage, murine model results are promising for translation to clinical applications [134,135]. mAb-therapeutic response can be measured with this imaging method as well [136]. This modality may also be useful in characterizing cancers of the GI tract, such as colon cancer, given the specificity of mAb technologies [136].

3.2.6. Ultrasonography

Using sound waves, ultrasonography (US) provides real-time images of the body’s interior. For determining IBD presence and extent, bowel wall thickness is the primary factor considered with US modalities [99,137,138,139]. Given its non-invasive nature and ability to render images in real-time, US is heavily favored for IBD imaging and analysis. US modalities do not expose patients to any radiation, are widely available, and remain generally inexpensive [99,140]. Studied specificity and selectivity values for US usage in IBD cases can be seen in .

There are several drawbacks to US imaging for IBD. For one, US has been primarily used with CD patients, limiting its effectiveness for UC cases [137]. Further, one meta-analysis indicates US is used more in Europe than in the United States [19]. This indicates that the accuracy for US techniques, given clinician exposure and usage, may be lower in the United States in comparison to Europe. The time required and accuracy of the imaging are heavily dependent on the experience of the clinician and size of the patient.

3.2.7. Contrast-Enhanced US

Some IBD patients may still exhibit wall thickening without active inflammation [141,142,143,144]. In these cases, US could lead to inappropriate therapy for the patient as the symptom intensity misaligns with the proposed treatment. To increase the accuracy of US in these and general IBD cases, contrast enhanced ultrasonography (CEUS) may be used. CEUS uses a intravenously applied microbubble contrast agent, such as sulfur hexafluoride, to show bowel wall enhancement and mesentery [144,145]. CEUS provides real-time information on the vascularity of the scanned area. Since IBD causes vascular alterations in affected areas, this information gives clinicians an understanding on IBD activity in the patient [144,145,146,147,148]. In general, CEUS appears to provide greater clinical certainty in evaluating IBD in patients.

3.2.8. Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) produces three-dimensional anatomical images of patients. In imaging the GI tract, especially for small bowel analysis, MR enterography (MRE), MR enteroclysis, and MR fistulography are the commonly used procedures [99,149]. For both the small and large bowel, intra and extra mural involvement can be measured with the appropriate contrast agents such as barium suspensions [99,150]. These agents induce bowel wall distension, ensuring easier detection of bowel wall complications, and fat suppression for ease of image interpretation [99,150,151]. Fat stranding, wall thickening, and intestinal strictures are all evidence for IBD found in MRI analyses [99,152]. MRI techniques do not use ionizing radiation to acquire images, making them favorable over CT modalities, especially for young patients. Additionally, MRI produces high resolution images while permitting significantly improved soft tissue contrast as compared to CT [149].

As with previously analyzed modalities requiring contrast agents, MRI cannot be used with patients who are allergic to contrast agents. Additionally, the long scan time (compared to US, for example) is logistically inconvenient for patients, and may require sedation [99]. Further, reference information and clinician or technology-induced bias can lead to improper image assessment [19,119,143].

3.2.9. Multispectral Optoacoustic Tomography

By stimulating patient tissues with lasers, ultrasound waves are generated. These waves can be read and interpreted to understand tissue characteristics inside patients. This phenomenon is the basis for multispectral optoacoustic tomography (MSOT) technologies. MSOT is purely non-invasive in nature and allows for real-time imaging of patient tissue in vivo [66,153,154]. Images gathered by MSOT show the distribution of such molecules as hemoglobin and melanin in patient tissue, due to the difference in how these molecules absorb light [155]. This distribution is indicative of disease presence and behavior in patients. A study evaluating MSOT imaging of murine colitis showed the correlation between inflammation level and concentration of oxy-hemoglobin () [66]. In a separate study, clinical trials on CD patients have shown similar results: Increased oxy-hemoglobin levels with active CD compared to remission CD [153,156]. MSOT technologies are still undergoing clinical trials for widespread use and are primarily seen in Europe. Preliminary results reveal significant potential for MSOT in rapidly diagnosing and monitoring IBD.

Multispectral optoacoustic tomography (MSOT) (A–C) and colonoscopic (D–F) images of murine colitis progression. Images were taken at t = 0, 2, and 7 days after bacterial inoculation. Yellow arrows indicate areas of inflammation correlating with colitis [67].

In summary, inflammatory conditions such as diverticulitis and IBD can be diagnosed and analyzed by a wide range of imaging modalities. Further work is required to verify the accuracy and refine the safety or comfortability of some of the mentioned modalities. Emerging technologies such as immuno-PET and MSOT could prove increasingly beneficial to imaging and diagnostic accuracy while increasing patient compliance. Since inflammation is also consistent with infection, it is important for patients with diverticulitis and IBD to be regularly monitored for alternative infectious or malignant diseases.

Imaging Inflammation and Infection in the Gastrointestinal Tract

3.1. Diverticulitis

Diverticulitis is characterized by the presence of inflamed diverticula in the GI tract, most commonly the large intestine. Sixty-five percent of the elderly population and 5% of individuals 40 years old or younger will have diverticula, 25% of those individuals will have diverticulitis while the remaining are asymptomatic [74,75]. Symptomatic diverticulitis is frequently coupled with complications including anal bleeding, fistulas, perforation, and abscess formation [74,76,77,78]. The clinical misdiagnosis rate of diverticulitis is upwards of 50%, indicating the need for better diagnostic techniques [79]. Recently there has been a spark in the investigation of potential biomarkers as safe and effective ways to diagnosis and assist physicians in treating diverticulitis [74]. C-reactive protein levels >50 mg/L, in addition to left lower quadrant abdominal tenderness and absences of vomiting is indicative of diverticulitis [79,80]. Fecal calprotectin is derived from neutrophils, so its presence in the stool is a good indication of inflammation in the GI tract. A study done by Tursi et al. showed increased levels of fecal calprotectin concentrations in diverticulitis patients when compared to IBS and control patients [81]. This provides an appealing clinical tool for differentiation between IBS and diverticulitis, although it must be noted that IBS and diverticulitis can exist simultaneously. Increased levels of these biomarkers in the blood and stool strongly support a clinical diagnosis of diverticulitis but are not specific enough to fully replace initial imaging techniques.

3.1.1. X-ray

Contrast enemas have been used in an attempt to diagnose cases of diverticulitis [82,83]. Initially, barium had been used as the contrast agent, but the shift to water soluble contrast agents was made to minimize risk to the patient. Water soluble contrast agents eliminated the risk of barium peritonitis, decreased the wait time between injection and scan, and allowed for other imaging modalities to be utilized after the enema [76,84,85]. While water-soluble contrast enemas are extremely beneficial at showing morphological changes of the colon, they are limited in that they cannot indicate active inflammation which is a key marker of diverticulitis. Therefore, the enema is then incapable of making a complete diagnosis of diverticulitis without the assistance of another imaging modality or it may result in a misdiagnosis indicating a low sensitivity of contrast enemas () [86].

3.1.2. Computed Tomography

Computed tomography (CT) has many advantages when compared to the traditional contrast enema, which is why it is now accepted as the primary imaging modality for patients that present with abdominal pain. A CT scan will identify inflamed diverticula, bowel wall inflammation, pericolic fat stranding, and corresponding complications [9,10,11,83,87,88]. CT is capable of visualizing pericolonic and colonic complications which results in a more accurate diagnosis for the patient, along with better standard of care. Thirty percent of cases of diverticulitis are accompanied by complications including, fistulas, perforations, and abscesses. Accurate assessment of complications is crucial in the development of a treatment plan. CT is particularly beneficial in the management of abscesses since it can be used for percutaneous drainage of the abscesses. Such drainage eliminates the need for multiple surgeries, making CT more cost effective and lower risk for the patients [9,10,77,82,83,86,88,89,90,91].

Contrast agents are utilized in CT scans to achieve maximum colonic distension along with colonic opacification in order to better identify inflammatory wall thickening consistent with diverticulitis [90]. Opacification of the colon is necessary to differentiate between intra and extra luminal air and fluid cavities, indicating the presence of abscesses [11,90,92]. Oral contrast agents are beneficial to the visualization of loops within the small bowel, but lack in completely covering the colon. Oral contrast agents are limited by inconsistent opacification of the colon and a large waiting period, resulting in the infrequent use of these types of agents [11,92]. Intravenous contrast agents are advantageous due to their capability of enhancing inflammation in the abdominal and pelvic regions. Such enhancement permits a more accurate identification of other illnesses that may have similar clinical symptoms as diverticulitis [83,87]. The use of an intravenous contrast agent is associated with a higher risk to the patient, at no significant benefit in comparison to rectally administered contrast agents [11,92]. Rectally administered contrast agents are the safest and most efficient way of obtaining uniform opacification of the colon with maximum distention [90]. Gastrografin-based contrast agents are the most widely used agents when imaging the gastrointestinal tract [9,11]. The risks associated with rectal contrast agents are similar to those associated with performing an enema: there is a higher chance of exacerbating perforations or extravasation of contrast material [92].

3.1.3. Ultrasonography

Ultrasonography (US) is an extremely low cost and low risk imaging modality that is not frequently used for the diagnosis of diverticulitis due to its reliance on a technician and inferiority to CT. While ultrasound is non-invasive, provides real-time images, and is useful in identifying inflammation, abscesses, and bowel wall thickening, it is limited in that it cannot be used on obese patients and that is can be impeded by gas bubbles [77,87]. A meta-analysis of 6 CT studies and 6 US studies showed that CT was no better or worse than ultrasound at diagnosing diverticulitis (), but CT still remains the modality of choice due to its ability to detect a multitude of complications [12,77,91].

3.1.4. Magnetic Resonance Imaging

While magnetic resonance imaging (MRI) is not traditionally used when a patient presents with abdominal pain, it has proven to have a high sensitivity and specificity in the diagnosis of diverticulitis, especially with the introduction of an intravenous gadolinium-based contrast agent () [14,15,87]. MRI is superior to CT in that it lacks associated harmful ionizing radiation, thus an appealing and a safe alternative to CT, but gadolinium-based contrast agents remain somewhat controversial with potential Gadolinium toxicity [93,94]. However, the use of MRI in diagnosing diverticulitis is limited not only by its cost and time, but also by the motion of other organs to continue breathing while the scan is taking place [14]. Due to these obstacles, MRI remains in the shadow of other imaging modalities for diagnosis of diverticulitis.

3.1.5. Endoscopy

Many features that are indicative of a CT scan are also indicators of colorectal cancer. After a positive diagnosis is made using CT, it is standard procedure for the patient to get a follow up colonoscopy around 6 weeks after being diagnosed [9,95]. This is a preventative measure to ensure that the diagnosis of diverticulitis did not miss a diagnosis of colon cancer [77,82,87,91,95,96,97]. In a study conducted by Lau et al., 34% of patients’ follow up colonoscopies came back positive for further complications or misdiagnosis of the initial diverticulitis [97]. While there is nothing to indicate that a positive diagnosis for diverticulitis is correlated with a higher risk for colorectal cancer, it has been observed that patients who present with diverticular complications have been more likely to have a positive colonoscopy for colorectal cancer sometime after the diverticulitis diagnosis [77,97].

3.2. Irritable Bowel Disease

Irritable bowel disease (IBD) is expressed in two major forms: Crohn’s disease (CD) and ulcerative colitis (UC). For both manifestations, IBD symptoms are similar to those of other GI disorders and include abdominal pain or discomfort, weight loss, bloody stool, diarrhea, and nausea [98]. In the intestines, the small and large bowel walls thicken and abscesses, collections of fluid surrounded in the inflamed intestinal tissue, may form. Unlike other disorders, the intensity of IBD symptoms changes with time. Periods of high intensity symptoms are defined as “flare,” while times of low intensity symptoms indicate “remission” [99].

Incidence of IBD in the United States and Europe is increasing, with current estimates of the affected population in those countries exceeding 1.6 million and 3 million, respectively [99,100,101,102]. For the different manifestations of IBD, CD’s prevalence in children and adults is 58 and 241 cases per 100,000, respectively, while UC prevalence in children and adults is 34 and 263 cases per 100,000, respectively [102,103,104]. In the United States, CD incidence is currently estimated to be 3.1–14.6 cases per 100,000 person-years and UC incidence is estimated at 2.2–14.3 cases per 100,000 person-years [102,103]. IBD occurrence is spreading across the world as well, with observed incidences in developing countries [100]. Approximately 20% of IBD patients are diagnosed during their childhood [99,104]. The effects of IBD have long-term impacts on children, namely growth failure or delays in puberty onset [63,100]. In 10–15% of IBD cases, CD and UC cannot be distinguished based on how they present in the patient, who is given an “IBD-unclassified” diagnosis. IBD patients are also at an increased risk of developing colorectal cancer, primarily due to the chronic intestinal inflammation inherent to CD and UC [105,106]. Eaden et al., in their meta-analysis, showed that patients with UC developed a cumulative risk to develop colorectal cancer of 2%, 8%, and 18% at 10, 20, and 30 years, respectively, after disease development [105,106,107]. Another study by Beaugerie and Itzkowitz demonstrated that in North America and some countries in Europe, the risk of colorectal cancer in IBD patients is up to two times higher than the risk of the general public [108].

The need for rapid and accurate imaging of IBD and its manifestations is apparent given its increasing prevalence and worldwide impact. Various imaging methods are practiced for IBD identification and monitoring [99]. with potential new and more effective modalities entering the clinical landscape as time progresses.

3.2.1. Endoscopy

Endoscopy is usually among the first steps carried out in diagnosing IBD [109,110,111]. The most common endoscopic technique is colonoscopy. In this procedure, clinicians insert an endoscope, comprised of a white light and a camera, into the patient via the anus for direct visualization of the colon. Colonoscopy is a highly invasive procedure, proving undesirable for patients. Other endoscopic techniques that offer minimal invasion are practiced, such as single-balloon and double-balloon enteroscopy [111].

3.2.2. Chromoendoscopy

To improve the surveillance of dysplasia, lesions, and other abnormalities in mucosal topography, chromoendoscopy (CE) may be used [112,113,114]. In this technique, dilute dye (indigo carmine or methylene blue) is sprayed, within appropriate guidelines, onto the lumen of the colon using a dye spray catheter [113]. This dye better reveals the location and pattern of lesions present in the colon, aiding clinician analysis, biopsy, or removal of present tissue. Compared to standard white light colonoscopy, CE has proved to be superior in multiple studies on per-patient and per-lesion analysis [113,114]. Given this, in order to increase accuracy of analysis and dysplasia detection, most international subspecialty societies recommend the use of CE when examining IBD patients [112]. This accuracy is particularly beneficial for early detection of colorectal cancer in patients.

3.2.3. Computed Tomography

Given its ease-of-access, non-invasive nature, ability to scan intraluminal and extraluminal effects, and not requiring anesthesia due to short scan times, computed tomography (CT) is a highly favorable method for IBD imaging [115]. The rapid image acquisition is particularly beneficial for pediatric patients, who may be more susceptible to the harmful effects of anesthesia. IBD evaluation via CT typically requires application of both oral and IV contrast agents, such as the gastrogafin-based agents described above [99,116,117]. These agents distend and opacify the bowel to reveal where extraluminal fluids are collected and to best characterize the abnormalities (e.g., thickening) in the bowel wall. To detect mucosal enhancement, associated with inflammation of or lesions in the intestines, CT enterography (CTE) may be used, which requires application of neutral contrast agents (e.g., water) [99,117]. Cross-sectional images of patients reveal the type and extent of their intestinal inflammation. The location and degree of inflammation and wall thickening determines the manifestation of IBD [118]. Further, these factors are heavily considered when diagnosing patients with IBD as opposed to other diseases. Specificity and sensitivity values for CT studies of IBD are shown in .

As stated, CT images can be acquired quickly and does not require use of anesthetics. Further, they are easy to reproduce and possess high spatial resolution, presenting clearer images to clinicians. These factors alone make it a strong modality for imaging IBD patients. CTE may boast greater sensitivity and specificity over magnetic resonance enterography (MRE) [99,119,120]. CT is not without its disadvantages. The greatest apparent drawback with CT usage is the required patient exposure to radiation [99,121,122]. Given the chronic nature of IBD, patients need frequent imaging for monitoring disease progress and symptom flare. Repeated exposure to ionizing radiation is not ideal, especially given the increased risk of cancer produced in patients. This is especially undesirable for pediatric patients, of which there is a significant number. Other studies have shown that CT imaging, when compared to US and MRI, may actually possess lower specificity and sensitivity for IBD diagnoses, decreasing its overall reliability [19,123]. Another potential disadvantage is that CT cannot be performed in patients who are allergic to contrast agents used.

It should be noted that the prevalence of CT usage, and thus associated regional clinician skill, is much higher in the United States as compared to Europe, where US and MRI are favored [19]. For all these modalities, this disparity can affect the specificity and sensitivity results when looking at a global as opposed to regional scale.

3.2.4. Positron Emission Tomography

For analysis of IBD, particularly in symptom flare situations or pediatric diagnostic work-ups, CT scanning is paired with positron emission tomography (PET) [21,123,124,125,126,127]. PET molecular imaging tracks accumulation of molecular radiopharmaceutical ¹⁸F-FDG to determine inflamed areas. ¹⁸F-FDG is used as it is similar to glucose and experiences significant uptake by leukocytes activated by tissue damage and inflammation. In pairing PET with CT, three-dimensional CT reconstructions follow PET molecular imaging to confirm anatomical and structural information in vivo [124]. Many studies have confirmed the usefulness of PET/CT imaging, particularly in cases where IBD affects the small bowel [123,128,129,130,131,132,133]. Further, PET/CT is reported to have better sensitivity than endoscopy, though a lower specificity than ultrasound [21,123,125]. More studies are recommended to better characterize the effectiveness of this joint modality [125,128]. An example of PET/CT imaging is shown in .

¹⁸F-FDG PET/CT scan of ulcerative colitis (UC) patient. Extent of disease is seen on the left and in areas indicated by arrows in the right panel [124].

3.2.5. Immuno-PET

A relatively new modality for IBD imaging is immuno-PET. Using fragments of monoclonal antibodies (mAbs), innate immune cells, especially present during symptom flare of IBD, are targeted to track inflammation [134,135]. While testing of this modality is primarily still in the preclinical stage, murine model results are promising for translation to clinical applications [134,135]. mAb-therapeutic response can be measured with this imaging method as well [136]. This modality may also be useful in characterizing cancers of the GI tract, such as colon cancer, given the specificity of mAb technologies [136].

3.2.6. Ultrasonography

Using sound waves, ultrasonography (US) provides real-time images of the body’s interior. For determining IBD presence and extent, bowel wall thickness is the primary factor considered with US modalities [99,137,138,139]. Given its non-invasive nature and ability to render images in real-time, US is heavily favored for IBD imaging and analysis. US modalities do not expose patients to any radiation, are widely available, and remain generally inexpensive [99,140]. Studied specificity and selectivity values for US usage in IBD cases can be seen in .

There are several drawbacks to US imaging for IBD. For one, US has been primarily used with CD patients, limiting its effectiveness for UC cases [137]. Further, one meta-analysis indicates US is used more in Europe than in the United States [19]. This indicates that the accuracy for US techniques, given clinician exposure and usage, may be lower in the United States in comparison to Europe. The time required and accuracy of the imaging are heavily dependent on the experience of the clinician and size of the patient.

3.2.7. Contrast-Enhanced US

Some IBD patients may still exhibit wall thickening without active inflammation [141,142,143,144]. In these cases, US could lead to inappropriate therapy for the patient as the symptom intensity misaligns with the proposed treatment. To increase the accuracy of US in these and general IBD cases, contrast enhanced ultrasonography (CEUS) may be used. CEUS uses a intravenously applied microbubble contrast agent, such as sulfur hexafluoride, to show bowel wall enhancement and mesentery [144,145]. CEUS provides real-time information on the vascularity of the scanned area. Since IBD causes vascular alterations in affected areas, this information gives clinicians an understanding on IBD activity in the patient [144,145,146,147,148]. In general, CEUS appears to provide greater clinical certainty in evaluating IBD in patients.

3.2.8. Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) produces three-dimensional anatomical images of patients. In imaging the GI tract, especially for small bowel analysis, MR enterography (MRE), MR enteroclysis, and MR fistulography are the commonly used procedures [99,149]. For both the small and large bowel, intra and extra mural involvement can be measured with the appropriate contrast agents such as barium suspensions [99,150]. These agents induce bowel wall distension, ensuring easier detection of bowel wall complications, and fat suppression for ease of image interpretation [99,150,151]. Fat stranding, wall thickening, and intestinal strictures are all evidence for IBD found in MRI analyses [99,152]. MRI techniques do not use ionizing radiation to acquire images, making them favorable over CT modalities, especially for young patients. Additionally, MRI produces high resolution images while permitting significantly improved soft tissue contrast as compared to CT [149].

As with previously analyzed modalities requiring contrast agents, MRI cannot be used with patients who are allergic to contrast agents. Additionally, the long scan time (compared to US, for example) is logistically inconvenient for patients, and may require sedation [99]. Further, reference information and clinician or technology-induced bias can lead to improper image assessment [19,119,143].

3.2.9. Multispectral Optoacoustic Tomography

By stimulating patient tissues with lasers, ultrasound waves are generated. These waves can be read and interpreted to understand tissue characteristics inside patients. This phenomenon is the basis for multispectral optoacoustic tomography (MSOT) technologies. MSOT is purely non-invasive in nature and allows for real-time imaging of patient tissue in vivo [66,153,154]. Images gathered by MSOT show the distribution of such molecules as hemoglobin and melanin in patient tissue, due to the difference in how these molecules absorb light [155]. This distribution is indicative of disease presence and behavior in patients. A study evaluating MSOT imaging of murine colitis showed the correlation between inflammation level and concentration of oxy-hemoglobin () [66]. In a separate study, clinical trials on CD patients have shown similar results: Increased oxy-hemoglobin levels with active CD compared to remission CD [153,156]. MSOT technologies are still undergoing clinical trials for widespread use and are primarily seen in Europe. Preliminary results reveal significant potential for MSOT in rapidly diagnosing and monitoring IBD.

Multispectral optoacoustic tomography (MSOT) (A–C) and colonoscopic (D–F) images of murine colitis progression. Images were taken at t = 0, 2, and 7 days after bacterial inoculation. Yellow arrows indicate areas of inflammation correlating with colitis [67].

In summary, inflammatory conditions such as diverticulitis and IBD can be diagnosed and analyzed by a wide range of imaging modalities. Further work is required to verify the accuracy and refine the safety or comfortability of some of the mentioned modalities. Emerging technologies such as immuno-PET and MSOT could prove increasingly beneficial to imaging and diagnostic accuracy while increasing patient compliance. Since inflammation is also consistent with infection, it is important for patients with diverticulitis and IBD to be regularly monitored for alternative infectious or malignant diseases.

Imaging Inflammation and Infection in the Gastrointestinal Tract

3.1. Diverticulitis

Diverticulitis is characterized by the presence of inflamed diverticula in the GI tract, most commonly the large intestine. Sixty-five percent of the elderly population and 5% of individuals 40 years old or younger will have diverticula, 25% of those individuals will have diverticulitis while the remaining are asymptomatic [74,75]. Symptomatic diverticulitis is frequently coupled with complications including anal bleeding, fistulas, perforation, and abscess formation [74,76,77,78]. The clinical misdiagnosis rate of diverticulitis is upwards of 50%, indicating the need for better diagnostic techniques [79]. Recently there has been a spark in the investigation of potential biomarkers as safe and effective ways to diagnosis and assist physicians in treating diverticulitis [74]. C-reactive protein levels >50 mg/L, in addition to left lower quadrant abdominal tenderness and absences of vomiting is indicative of diverticulitis [79,80]. Fecal calprotectin is derived from neutrophils, so its presence in the stool is a good indication of inflammation in the GI tract. A study done by Tursi et al. showed increased levels of fecal calprotectin concentrations in diverticulitis patients when compared to IBS and control patients [81]. This provides an appealing clinical tool for differentiation between IBS and diverticulitis, although it must be noted that IBS and diverticulitis can exist simultaneously. Increased levels of these biomarkers in the blood and stool strongly support a clinical diagnosis of diverticulitis but are not specific enough to fully replace initial imaging techniques.

3.1.1. X-ray

Contrast enemas have been used in an attempt to diagnose cases of diverticulitis [82,83]. Initially, barium had been used as the contrast agent, but the shift to water soluble contrast agents was made to minimize risk to the patient. Water soluble contrast agents eliminated the risk of barium peritonitis, decreased the wait time between injection and scan, and allowed for other imaging modalities to be utilized after the enema [76,84,85]. While water-soluble contrast enemas are extremely beneficial at showing morphological changes of the colon, they are limited in that they cannot indicate active inflammation which is a key marker of diverticulitis. Therefore, the enema is then incapable of making a complete diagnosis of diverticulitis without the assistance of another imaging modality or it may result in a misdiagnosis indicating a low sensitivity of contrast enemas () [86].

3.1.2. Computed Tomography

Computed tomography (CT) has many advantages when compared to the traditional contrast enema, which is why it is now accepted as the primary imaging modality for patients that present with abdominal pain. A CT scan will identify inflamed diverticula, bowel wall inflammation, pericolic fat stranding, and corresponding complications [9,10,11,83,87,88]. CT is capable of visualizing pericolonic and colonic complications which results in a more accurate diagnosis for the patient, along with better standard of care. Thirty percent of cases of diverticulitis are accompanied by complications including, fistulas, perforations, and abscesses. Accurate assessment of complications is crucial in the development of a treatment plan. CT is particularly beneficial in the management of abscesses since it can be used for percutaneous drainage of the abscesses. Such drainage eliminates the need for multiple surgeries, making CT more cost effective and lower risk for the patients [9,10,77,82,83,86,88,89,90,91].

Contrast agents are utilized in CT scans to achieve maximum colonic distension along with colonic opacification in order to better identify inflammatory wall thickening consistent with diverticulitis [90]. Opacification of the colon is necessary to differentiate between intra and extra luminal air and fluid cavities, indicating the presence of abscesses [11,90,92]. Oral contrast agents are beneficial to the visualization of loops within the small bowel, but lack in completely covering the colon. Oral contrast agents are limited by inconsistent opacification of the colon and a large waiting period, resulting in the infrequent use of these types of agents [11,92]. Intravenous contrast agents are advantageous due to their capability of enhancing inflammation in the abdominal and pelvic regions. Such enhancement permits a more accurate identification of other illnesses that may have similar clinical symptoms as diverticulitis [83,87]. The use of an intravenous contrast agent is associated with a higher risk to the patient, at no significant benefit in comparison to rectally administered contrast agents [11,92]. Rectally administered contrast agents are the safest and most efficient way of obtaining uniform opacification of the colon with maximum distention [90]. Gastrografin-based contrast agents are the most widely used agents when imaging the gastrointestinal tract [9,11]. The risks associated with rectal contrast agents are similar to those associated with performing an enema: there is a higher chance of exacerbating perforations or extravasation of contrast material [92].

3.1.3. Ultrasonography

Ultrasonography (US) is an extremely low cost and low risk imaging modality that is not frequently used for the diagnosis of diverticulitis due to its reliance on a technician and inferiority to CT. While ultrasound is non-invasive, provides real-time images, and is useful in identifying inflammation, abscesses, and bowel wall thickening, it is limited in that it cannot be used on obese patients and that is can be impeded by gas bubbles [77,87]. A meta-analysis of 6 CT studies and 6 US studies showed that CT was no better or worse than ultrasound at diagnosing diverticulitis (), but CT still remains the modality of choice due to its ability to detect a multitude of complications [12,77,91].

3.1.4. Magnetic Resonance Imaging

While magnetic resonance imaging (MRI) is not traditionally used when a patient presents with abdominal pain, it has proven to have a high sensitivity and specificity in the diagnosis of diverticulitis, especially with the introduction of an intravenous gadolinium-based contrast agent () [14,15,87]. MRI is superior to CT in that it lacks associated harmful ionizing radiation, thus an appealing and a safe alternative to CT, but gadolinium-based contrast agents remain somewhat controversial with potential Gadolinium toxicity [93,94]. However, the use of MRI in diagnosing diverticulitis is limited not only by its cost and time, but also by the motion of other organs to continue breathing while the scan is taking place [14]. Due to these obstacles, MRI remains in the shadow of other imaging modalities for diagnosis of diverticulitis.

3.1.5. Endoscopy

Many features that are indicative of a CT scan are also indicators of colorectal cancer. After a positive diagnosis is made using CT, it is standard procedure for the patient to get a follow up colonoscopy around 6 weeks after being diagnosed [9,95]. This is a preventative measure to ensure that the diagnosis of diverticulitis did not miss a diagnosis of colon cancer [77,82,87,91,95,96,97]. In a study conducted by Lau et al., 34% of patients’ follow up colonoscopies came back positive for further complications or misdiagnosis of the initial diverticulitis [97]. While there is nothing to indicate that a positive diagnosis for diverticulitis is correlated with a higher risk for colorectal cancer, it has been observed that patients who present with diverticular complications have been more likely to have a positive colonoscopy for colorectal cancer sometime after the diverticulitis diagnosis [77,97].

3.2. Irritable Bowel Disease

Irritable bowel disease (IBD) is expressed in two major forms: Crohn’s disease (CD) and ulcerative colitis (UC). For both manifestations, IBD symptoms are similar to those of other GI disorders and include abdominal pain or discomfort, weight loss, bloody stool, diarrhea, and nausea [98]. In the intestines, the small and large bowel walls thicken and abscesses, collections of fluid surrounded in the inflamed intestinal tissue, may form. Unlike other disorders, the intensity of IBD symptoms changes with time. Periods of high intensity symptoms are defined as “flare,” while times of low intensity symptoms indicate “remission” [99].

Incidence of IBD in the United States and Europe is increasing, with current estimates of the affected population in those countries exceeding 1.6 million and 3 million, respectively [99,100,101,102]. For the different manifestations of IBD, CD’s prevalence in children and adults is 58 and 241 cases per 100,000, respectively, while UC prevalence in children and adults is 34 and 263 cases per 100,000, respectively [102,103,104]. In the United States, CD incidence is currently estimated to be 3.1–14.6 cases per 100,000 person-years and UC incidence is estimated at 2.2–14.3 cases per 100,000 person-years [102,103]. IBD occurrence is spreading across the world as well, with observed incidences in developing countries [100]. Approximately 20% of IBD patients are diagnosed during their childhood [99,104]. The effects of IBD have long-term impacts on children, namely growth failure or delays in puberty onset [63,100]. In 10–15% of IBD cases, CD and UC cannot be distinguished based on how they present in the patient, who is given an “IBD-unclassified” diagnosis. IBD patients are also at an increased risk of developing colorectal cancer, primarily due to the chronic intestinal inflammation inherent to CD and UC [105,106]. Eaden et al., in their meta-analysis, showed that patients with UC developed a cumulative risk to develop colorectal cancer of 2%, 8%, and 18% at 10, 20, and 30 years, respectively, after disease development [105,106,107]. Another study by Beaugerie and Itzkowitz demonstrated that in North America and some countries in Europe, the risk of colorectal cancer in IBD patients is up to two times higher than the risk of the general public [108].

The need for rapid and accurate imaging of IBD and its manifestations is apparent given its increasing prevalence and worldwide impact. Various imaging methods are practiced for IBD identification and monitoring [99]. with potential new and more effective modalities entering the clinical landscape as time progresses.

3.2.1. Endoscopy

Endoscopy is usually among the first steps carried out in diagnosing IBD [109,110,111]. The most common endoscopic technique is colonoscopy. In this procedure, clinicians insert an endoscope, comprised of a white light and a camera, into the patient via the anus for direct visualization of the colon. Colonoscopy is a highly invasive procedure, proving undesirable for patients. Other endoscopic techniques that offer minimal invasion are practiced, such as single-balloon and double-balloon enteroscopy [111].

3.2.2. Chromoendoscopy

To improve the surveillance of dysplasia, lesions, and other abnormalities in mucosal topography, chromoendoscopy (CE) may be used [112,113,114]. In this technique, dilute dye (indigo carmine or methylene blue) is sprayed, within appropriate guidelines, onto the lumen of the colon using a dye spray catheter [113]. This dye better reveals the location and pattern of lesions present in the colon, aiding clinician analysis, biopsy, or removal of present tissue. Compared to standard white light colonoscopy, CE has proved to be superior in multiple studies on per-patient and per-lesion analysis [113,114]. Given this, in order to increase accuracy of analysis and dysplasia detection, most international subspecialty societies recommend the use of CE when examining IBD patients [112]. This accuracy is particularly beneficial for early detection of colorectal cancer in patients.

3.2.3. Computed Tomography

Given its ease-of-access, non-invasive nature, ability to scan intraluminal and extraluminal effects, and not requiring anesthesia due to short scan times, computed tomography (CT) is a highly favorable method for IBD imaging [115]. The rapid image acquisition is particularly beneficial for pediatric patients, who may be more susceptible to the harmful effects of anesthesia. IBD evaluation via CT typically requires application of both oral and IV contrast agents, such as the gastrogafin-based agents described above [99,116,117]. These agents distend and opacify the bowel to reveal where extraluminal fluids are collected and to best characterize the abnormalities (e.g., thickening) in the bowel wall. To detect mucosal enhancement, associated with inflammation of or lesions in the intestines, CT enterography (CTE) may be used, which requires application of neutral contrast agents (e.g., water) [99,117]. Cross-sectional images of patients reveal the type and extent of their intestinal inflammation. The location and degree of inflammation and wall thickening determines the manifestation of IBD [118]. Further, these factors are heavily considered when diagnosing patients with IBD as opposed to other diseases. Specificity and sensitivity values for CT studies of IBD are shown in .

As stated, CT images can be acquired quickly and does not require use of anesthetics. Further, they are easy to reproduce and possess high spatial resolution, presenting clearer images to clinicians. These factors alone make it a strong modality for imaging IBD patients. CTE may boast greater sensitivity and specificity over magnetic resonance enterography (MRE) [99,119,120]. CT is not without its disadvantages. The greatest apparent drawback with CT usage is the required patient exposure to radiation [99,121,122]. Given the chronic nature of IBD, patients need frequent imaging for monitoring disease progress and symptom flare. Repeated exposure to ionizing radiation is not ideal, especially given the increased risk of cancer produced in patients. This is especially undesirable for pediatric patients, of which there is a significant number. Other studies have shown that CT imaging, when compared to US and MRI, may actually possess lower specificity and sensitivity for IBD diagnoses, decreasing its overall reliability [19,123]. Another potential disadvantage is that CT cannot be performed in patients who are allergic to contrast agents used.

It should be noted that the prevalence of CT usage, and thus associated regional clinician skill, is much higher in the United States as compared to Europe, where US and MRI are favored [19]. For all these modalities, this disparity can affect the specificity and sensitivity results when looking at a global as opposed to regional scale.

3.2.4. Positron Emission Tomography

For analysis of IBD, particularly in symptom flare situations or pediatric diagnostic work-ups, CT scanning is paired with positron emission tomography (PET) [21,123,124,125,126,127]. PET molecular imaging tracks accumulation of molecular radiopharmaceutical ¹⁸F-FDG to determine inflamed areas. ¹⁸F-FDG is used as it is similar to glucose and experiences significant uptake by leukocytes activated by tissue damage and inflammation. In pairing PET with CT, three-dimensional CT reconstructions follow PET molecular imaging to confirm anatomical and structural information in vivo [124]. Many studies have confirmed the usefulness of PET/CT imaging, particularly in cases where IBD affects the small bowel [123,128,129,130,131,132,133]. Further, PET/CT is reported to have better sensitivity than endoscopy, though a lower specificity than ultrasound [21,123,125]. More studies are recommended to better characterize the effectiveness of this joint modality [125,128]. An example of PET/CT imaging is shown in .

¹⁸F-FDG PET/CT scan of ulcerative colitis (UC) patient. Extent of disease is seen on the left and in areas indicated by arrows in the right panel [124].

3.2.5. Immuno-PET

A relatively new modality for IBD imaging is immuno-PET. Using fragments of monoclonal antibodies (mAbs), innate immune cells, especially present during symptom flare of IBD, are targeted to track inflammation [134,135]. While testing of this modality is primarily still in the preclinical stage, murine model results are promising for translation to clinical applications [134,135]. mAb-therapeutic response can be measured with this imaging method as well [136]. This modality may also be useful in characterizing cancers of the GI tract, such as colon cancer, given the specificity of mAb technologies [136].

3.2.6. Ultrasonography

Using sound waves, ultrasonography (US) provides real-time images of the body’s interior. For determining IBD presence and extent, bowel wall thickness is the primary factor considered with US modalities [99,137,138,139]. Given its non-invasive nature and ability to render images in real-time, US is heavily favored for IBD imaging and analysis. US modalities do not expose patients to any radiation, are widely available, and remain generally inexpensive [99,140]. Studied specificity and selectivity values for US usage in IBD cases can be seen in .

There are several drawbacks to US imaging for IBD. For one, US has been primarily used with CD patients, limiting its effectiveness for UC cases [137]. Further, one meta-analysis indicates US is used more in Europe than in the United States [19]. This indicates that the accuracy for US techniques, given clinician exposure and usage, may be lower in the United States in comparison to Europe. The time required and accuracy of the imaging are heavily dependent on the experience of the clinician and size of the patient.

3.2.7. Contrast-Enhanced US

Some IBD patients may still exhibit wall thickening without active inflammation [141,142,143,144]. In these cases, US could lead to inappropriate therapy for the patient as the symptom intensity misaligns with the proposed treatment. To increase the accuracy of US in these and general IBD cases, contrast enhanced ultrasonography (CEUS) may be used. CEUS uses a intravenously applied microbubble contrast agent, such as sulfur hexafluoride, to show bowel wall enhancement and mesentery [144,145]. CEUS provides real-time information on the vascularity of the scanned area. Since IBD causes vascular alterations in affected areas, this information gives clinicians an understanding on IBD activity in the patient [144,145,146,147,148]. In general, CEUS appears to provide greater clinical certainty in evaluating IBD in patients.

3.2.8. Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) produces three-dimensional anatomical images of patients. In imaging the GI tract, especially for small bowel analysis, MR enterography (MRE), MR enteroclysis, and MR fistulography are the commonly used procedures [99,149]. For both the small and large bowel, intra and extra mural involvement can be measured with the appropriate contrast agents such as barium suspensions [99,150]. These agents induce bowel wall distension, ensuring easier detection of bowel wall complications, and fat suppression for ease of image interpretation [99,150,151]. Fat stranding, wall thickening, and intestinal strictures are all evidence for IBD found in MRI analyses [99,152]. MRI techniques do not use ionizing radiation to acquire images, making them favorable over CT modalities, especially for young patients. Additionally, MRI produces high resolution images while permitting significantly improved soft tissue contrast as compared to CT [149].

As with previously analyzed modalities requiring contrast agents, MRI cannot be used with patients who are allergic to contrast agents. Additionally, the long scan time (compared to US, for example) is logistically inconvenient for patients, and may require sedation [99]. Further, reference information and clinician or technology-induced bias can lead to improper image assessment [19,119,143].

3.2.9. Multispectral Optoacoustic Tomography

By stimulating patient tissues with lasers, ultrasound waves are generated. These waves can be read and interpreted to understand tissue characteristics inside patients. This phenomenon is the basis for multispectral optoacoustic tomography (MSOT) technologies. MSOT is purely non-invasive in nature and allows for real-time imaging of patient tissue in vivo [66,153,154]. Images gathered by MSOT show the distribution of such molecules as hemoglobin and melanin in patient tissue, due to the difference in how these molecules absorb light [155]. This distribution is indicative of disease presence and behavior in patients. A study evaluating MSOT imaging of murine colitis showed the correlation between inflammation level and concentration of oxy-hemoglobin () [66]. In a separate study, clinical trials on CD patients have shown similar results: Increased oxy-hemoglobin levels with active CD compared to remission CD [153,156]. MSOT technologies are still undergoing clinical trials for widespread use and are primarily seen in Europe. Preliminary results reveal significant potential for MSOT in rapidly diagnosing and monitoring IBD.

Multispectral optoacoustic tomography (MSOT) (A–C) and colonoscopic (D–F) images of murine colitis progression. Images were taken at t = 0, 2, and 7 days after bacterial inoculation. Yellow arrows indicate areas of inflammation correlating with colitis [67].

In summary, inflammatory conditions such as diverticulitis and IBD can be diagnosed and analyzed by a wide range of imaging modalities. Further work is required to verify the accuracy and refine the safety or comfortability of some of the mentioned modalities. Emerging technologies such as immuno-PET and MSOT could prove increasingly beneficial to imaging and diagnostic accuracy while increasing patient compliance. Since inflammation is also consistent with infection, it is important for patients with diverticulitis and IBD to be regularly monitored for alternative infectious or malignant diseases.

Imaging Inflammation and Infection in the Gastrointestinal Tract

3.1. Diverticulitis

Diverticulitis is characterized by the presence of inflamed diverticula in the GI tract, most commonly the large intestine. Sixty-five percent of the elderly population and 5% of individuals 40 years old or younger will have diverticula, 25% of those individuals will have diverticulitis while the remaining are asymptomatic [74,75]. Symptomatic diverticulitis is frequently coupled with complications including anal bleeding, fistulas, perforation, and abscess formation [74,76,77,78]. The clinical misdiagnosis rate of diverticulitis is upwards of 50%, indicating the need for better diagnostic techniques [79]. Recently there has been a spark in the investigation of potential biomarkers as safe and effective ways to diagnosis and assist physicians in treating diverticulitis [74]. C-reactive protein levels >50 mg/L, in addition to left lower quadrant abdominal tenderness and absences of vomiting is indicative of diverticulitis [79,80]. Fecal calprotectin is derived from neutrophils, so its presence in the stool is a good indication of inflammation in the GI tract. A study done by Tursi et al. showed increased levels of fecal calprotectin concentrations in diverticulitis patients when compared to IBS and control patients [81]. This provides an appealing clinical tool for differentiation between IBS and diverticulitis, although it must be noted that IBS and diverticulitis can exist simultaneously. Increased levels of these biomarkers in the blood and stool strongly support a clinical diagnosis of diverticulitis but are not specific enough to fully replace initial imaging techniques.

3.1.1. X-ray

Contrast enemas have been used in an attempt to diagnose cases of diverticulitis [82,83]. Initially, barium had been used as the contrast agent, but the shift to water soluble contrast agents was made to minimize risk to the patient. Water soluble contrast agents eliminated the risk of barium peritonitis, decreased the wait time between injection and scan, and allowed for other imaging modalities to be utilized after the enema [76,84,85]. While water-soluble contrast enemas are extremely beneficial at showing morphological changes of the colon, they are limited in that they cannot indicate active inflammation which is a key marker of diverticulitis. Therefore, the enema is then incapable of making a complete diagnosis of diverticulitis without the assistance of another imaging modality or it may result in a misdiagnosis indicating a low sensitivity of contrast enemas () [86].

3.1.2. Computed Tomography

Computed tomography (CT) has many advantages when compared to the traditional contrast enema, which is why it is now accepted as the primary imaging modality for patients that present with abdominal pain. A CT scan will identify inflamed diverticula, bowel wall inflammation, pericolic fat stranding, and corresponding complications [9,10,11,83,87,88]. CT is capable of visualizing pericolonic and colonic complications which results in a more accurate diagnosis for the patient, along with better standard of care. Thirty percent of cases of diverticulitis are accompanied by complications including, fistulas, perforations, and abscesses. Accurate assessment of complications is crucial in the development of a treatment plan. CT is particularly beneficial in the management of abscesses since it can be used for percutaneous drainage of the abscesses. Such drainage eliminates the need for multiple surgeries, making CT more cost effective and lower risk for the patients [9,10,77,82,83,86,88,89,90,91].

Contrast agents are utilized in CT scans to achieve maximum colonic distension along with colonic opacification in order to better identify inflammatory wall thickening consistent with diverticulitis [90]. Opacification of the colon is necessary to differentiate between intra and extra luminal air and fluid cavities, indicating the presence of abscesses [11,90,92]. Oral contrast agents are beneficial to the visualization of loops within the small bowel, but lack in completely covering the colon. Oral contrast agents are limited by inconsistent opacification of the colon and a large waiting period, resulting in the infrequent use of these types of agents [11,92]. Intravenous contrast agents are advantageous due to their capability of enhancing inflammation in the abdominal and pelvic regions. Such enhancement permits a more accurate identification of other illnesses that may have similar clinical symptoms as diverticulitis [83,87]. The use of an intravenous contrast agent is associated with a higher risk to the patient, at no significant benefit in comparison to rectally administered contrast agents [11,92]. Rectally administered contrast agents are the safest and most efficient way of obtaining uniform opacification of the colon with maximum distention [90]. Gastrografin-based contrast agents are the most widely used agents when imaging the gastrointestinal tract [9,11]. The risks associated with rectal contrast agents are similar to those associated with performing an enema: there is a higher chance of exacerbating perforations or extravasation of contrast material [92].

3.1.3. Ultrasonography

Ultrasonography (US) is an extremely low cost and low risk imaging modality that is not frequently used for the diagnosis of diverticulitis due to its reliance on a technician and inferiority to CT. While ultrasound is non-invasive, provides real-time images, and is useful in identifying inflammation, abscesses, and bowel wall thickening, it is limited in that it cannot be used on obese patients and that is can be impeded by gas bubbles [77,87]. A meta-analysis of 6 CT studies and 6 US studies showed that CT was no better or worse than ultrasound at diagnosing diverticulitis (), but CT still remains the modality of choice due to its ability to detect a multitude of complications [12,77,91].

3.1.4. Magnetic Resonance Imaging

While magnetic resonance imaging (MRI) is not traditionally used when a patient presents with abdominal pain, it has proven to have a high sensitivity and specificity in the diagnosis of diverticulitis, especially with the introduction of an intravenous gadolinium-based contrast agent () [14,15,87]. MRI is superior to CT in that it lacks associated harmful ionizing radiation, thus an appealing and a safe alternative to CT, but gadolinium-based contrast agents remain somewhat controversial with potential Gadolinium toxicity [93,94]. However, the use of MRI in diagnosing diverticulitis is limited not only by its cost and time, but also by the motion of other organs to continue breathing while the scan is taking place [14]. Due to these obstacles, MRI remains in the shadow of other imaging modalities for diagnosis of diverticulitis.

3.1.5. Endoscopy

Many features that are indicative of a CT scan are also indicators of colorectal cancer. After a positive diagnosis is made using CT, it is standard procedure for the patient to get a follow up colonoscopy around 6 weeks after being diagnosed [9,95]. This is a preventative measure to ensure that the diagnosis of diverticulitis did not miss a diagnosis of colon cancer [77,82,87,91,95,96,97]. In a study conducted by Lau et al., 34% of patients’ follow up colonoscopies came back positive for further complications or misdiagnosis of the initial diverticulitis [97]. While there is nothing to indicate that a positive diagnosis for diverticulitis is correlated with a higher risk for colorectal cancer, it has been observed that patients who present with diverticular complications have been more likely to have a positive colonoscopy for colorectal cancer sometime after the diverticulitis diagnosis [77,97].

3.2. Irritable Bowel Disease

Irritable bowel disease (IBD) is expressed in two major forms: Crohn’s disease (CD) and ulcerative colitis (UC). For both manifestations, IBD symptoms are similar to those of other GI disorders and include abdominal pain or discomfort, weight loss, bloody stool, diarrhea, and nausea [98]. In the intestines, the small and large bowel walls thicken and abscesses, collections of fluid surrounded in the inflamed intestinal tissue, may form. Unlike other disorders, the intensity of IBD symptoms changes with time. Periods of high intensity symptoms are defined as “flare,” while times of low intensity symptoms indicate “remission” [99].

Incidence of IBD in the United States and Europe is increasing, with current estimates of the affected population in those countries exceeding 1.6 million and 3 million, respectively [99,100,101,102]. For the different manifestations of IBD, CD’s prevalence in children and adults is 58 and 241 cases per 100,000, respectively, while UC prevalence in children and adults is 34 and 263 cases per 100,000, respectively [102,103,104]. In the United States, CD incidence is currently estimated to be 3.1–14.6 cases per 100,000 person-years and UC incidence is estimated at 2.2–14.3 cases per 100,000 person-years [102,103]. IBD occurrence is spreading across the world as well, with observed incidences in developing countries [100]. Approximately 20% of IBD patients are diagnosed during their childhood [99,104]. The effects of IBD have long-term impacts on children, namely growth failure or delays in puberty onset [63,100]. In 10–15% of IBD cases, CD and UC cannot be distinguished based on how they present in the patient, who is given an “IBD-unclassified” diagnosis. IBD patients are also at an increased risk of developing colorectal cancer, primarily due to the chronic intestinal inflammation inherent to CD and UC [105,106]. Eaden et al., in their meta-analysis, showed that patients with UC developed a cumulative risk to develop colorectal cancer of 2%, 8%, and 18% at 10, 20, and 30 years, respectively, after disease development [105,106,107]. Another study by Beaugerie and Itzkowitz demonstrated that in North America and some countries in Europe, the risk of colorectal cancer in IBD patients is up to two times higher than the risk of the general public [108].

The need for rapid and accurate imaging of IBD and its manifestations is apparent given its increasing prevalence and worldwide impact. Various imaging methods are practiced for IBD identification and monitoring [99]. with potential new and more effective modalities entering the clinical landscape as time progresses.

3.2.1. Endoscopy

Endoscopy is usually among the first steps carried out in diagnosing IBD [109,110,111]. The most common endoscopic technique is colonoscopy. In this procedure, clinicians insert an endoscope, comprised of a white light and a camera, into the patient via the anus for direct visualization of the colon. Colonoscopy is a highly invasive procedure, proving undesirable for patients. Other endoscopic techniques that offer minimal invasion are practiced, such as single-balloon and double-balloon enteroscopy [111].

3.2.2. Chromoendoscopy

To improve the surveillance of dysplasia, lesions, and other abnormalities in mucosal topography, chromoendoscopy (CE) may be used [112,113,114]. In this technique, dilute dye (indigo carmine or methylene blue) is sprayed, within appropriate guidelines, onto the lumen of the colon using a dye spray catheter [113]. This dye better reveals the location and pattern of lesions present in the colon, aiding clinician analysis, biopsy, or removal of present tissue. Compared to standard white light colonoscopy, CE has proved to be superior in multiple studies on per-patient and per-lesion analysis [113,114]. Given this, in order to increase accuracy of analysis and dysplasia detection, most international subspecialty societies recommend the use of CE when examining IBD patients [112]. This accuracy is particularly beneficial for early detection of colorectal cancer in patients.

3.2.3. Computed Tomography

Given its ease-of-access, non-invasive nature, ability to scan intraluminal and extraluminal effects, and not requiring anesthesia due to short scan times, computed tomography (CT) is a highly favorable method for IBD imaging [115]. The rapid image acquisition is particularly beneficial for pediatric patients, who may be more susceptible to the harmful effects of anesthesia. IBD evaluation via CT typically requires application of both oral and IV contrast agents, such as the gastrogafin-based agents described above [99,116,117]. These agents distend and opacify the bowel to reveal where extraluminal fluids are collected and to best characterize the abnormalities (e.g., thickening) in the bowel wall. To detect mucosal enhancement, associated with inflammation of or lesions in the intestines, CT enterography (CTE) may be used, which requires application of neutral contrast agents (e.g., water) [99,117]. Cross-sectional images of patients reveal the type and extent of their intestinal inflammation. The location and degree of inflammation and wall thickening determines the manifestation of IBD [118]. Further, these factors are heavily considered when diagnosing patients with IBD as opposed to other diseases. Specificity and sensitivity values for CT studies of IBD are shown in .

As stated, CT images can be acquired quickly and does not require use of anesthetics. Further, they are easy to reproduce and possess high spatial resolution, presenting clearer images to clinicians. These factors alone make it a strong modality for imaging IBD patients. CTE may boast greater sensitivity and specificity over magnetic resonance enterography (MRE) [99,119,120]. CT is not without its disadvantages. The greatest apparent drawback with CT usage is the required patient exposure to radiation [99,121,122]. Given the chronic nature of IBD, patients need frequent imaging for monitoring disease progress and symptom flare. Repeated exposure to ionizing radiation is not ideal, especially given the increased risk of cancer produced in patients. This is especially undesirable for pediatric patients, of which there is a significant number. Other studies have shown that CT imaging, when compared to US and MRI, may actually possess lower specificity and sensitivity for IBD diagnoses, decreasing its overall reliability [19,123]. Another potential disadvantage is that CT cannot be performed in patients who are allergic to contrast agents used.

It should be noted that the prevalence of CT usage, and thus associated regional clinician skill, is much higher in the United States as compared to Europe, where US and MRI are favored [19]. For all these modalities, this disparity can affect the specificity and sensitivity results when looking at a global as opposed to regional scale.

3.2.4. Positron Emission Tomography

For analysis of IBD, particularly in symptom flare situations or pediatric diagnostic work-ups, CT scanning is paired with positron emission tomography (PET) [21,123,124,125,126,127]. PET molecular imaging tracks accumulation of molecular radiopharmaceutical ¹⁸F-FDG to determine inflamed areas. ¹⁸F-FDG is used as it is similar to glucose and experiences significant uptake by leukocytes activated by tissue damage and inflammation. In pairing PET with CT, three-dimensional CT reconstructions follow PET molecular imaging to confirm anatomical and structural information in vivo [124]. Many studies have confirmed the usefulness of PET/CT imaging, particularly in cases where IBD affects the small bowel [123,128,129,130,131,132,133]. Further, PET/CT is reported to have better sensitivity than endoscopy, though a lower specificity than ultrasound [21,123,125]. More studies are recommended to better characterize the effectiveness of this joint modality [125,128]. An example of PET/CT imaging is shown in .

¹⁸F-FDG PET/CT scan of ulcerative colitis (UC) patient. Extent of disease is seen on the left and in areas indicated by arrows in the right panel [124].

3.2.5. Immuno-PET

A relatively new modality for IBD imaging is immuno-PET. Using fragments of monoclonal antibodies (mAbs), innate immune cells, especially present during symptom flare of IBD, are targeted to track inflammation [134,135]. While testing of this modality is primarily still in the preclinical stage, murine model results are promising for translation to clinical applications [134,135]. mAb-therapeutic response can be measured with this imaging method as well [136]. This modality may also be useful in characterizing cancers of the GI tract, such as colon cancer, given the specificity of mAb technologies [136].

3.2.6. Ultrasonography

Using sound waves, ultrasonography (US) provides real-time images of the body’s interior. For determining IBD presence and extent, bowel wall thickness is the primary factor considered with US modalities [99,137,138,139]. Given its non-invasive nature and ability to render images in real-time, US is heavily favored for IBD imaging and analysis. US modalities do not expose patients to any radiation, are widely available, and remain generally inexpensive [99,140]. Studied specificity and selectivity values for US usage in IBD cases can be seen in .

There are several drawbacks to US imaging for IBD. For one, US has been primarily used with CD patients, limiting its effectiveness for UC cases [137]. Further, one meta-analysis indicates US is used more in Europe than in the United States [19]. This indicates that the accuracy for US techniques, given clinician exposure and usage, may be lower in the United States in comparison to Europe. The time required and accuracy of the imaging are heavily dependent on the experience of the clinician and size of the patient.

3.2.7. Contrast-Enhanced US

Some IBD patients may still exhibit wall thickening without active inflammation [141,142,143,144]. In these cases, US could lead to inappropriate therapy for the patient as the symptom intensity misaligns with the proposed treatment. To increase the accuracy of US in these and general IBD cases, contrast enhanced ultrasonography (CEUS) may be used. CEUS uses a intravenously applied microbubble contrast agent, such as sulfur hexafluoride, to show bowel wall enhancement and mesentery [144,145]. CEUS provides real-time information on the vascularity of the scanned area. Since IBD causes vascular alterations in affected areas, this information gives clinicians an understanding on IBD activity in the patient [144,145,146,147,148]. In general, CEUS appears to provide greater clinical certainty in evaluating IBD in patients.

3.2.8. Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) produces three-dimensional anatomical images of patients. In imaging the GI tract, especially for small bowel analysis, MR enterography (MRE), MR enteroclysis, and MR fistulography are the commonly used procedures [99,149]. For both the small and large bowel, intra and extra mural involvement can be measured with the appropriate contrast agents such as barium suspensions [99,150]. These agents induce bowel wall distension, ensuring easier detection of bowel wall complications, and fat suppression for ease of image interpretation [99,150,151]. Fat stranding, wall thickening, and intestinal strictures are all evidence for IBD found in MRI analyses [99,152]. MRI techniques do not use ionizing radiation to acquire images, making them favorable over CT modalities, especially for young patients. Additionally, MRI produces high resolution images while permitting significantly improved soft tissue contrast as compared to CT [149].

As with previously analyzed modalities requiring contrast agents, MRI cannot be used with patients who are allergic to contrast agents. Additionally, the long scan time (compared to US, for example) is logistically inconvenient for patients, and may require sedation [99]. Further, reference information and clinician or technology-induced bias can lead to improper image assessment [19,119,143].

3.2.9. Multispectral Optoacoustic Tomography

By stimulating patient tissues with lasers, ultrasound waves are generated. These waves can be read and interpreted to understand tissue characteristics inside patients. This phenomenon is the basis for multispectral optoacoustic tomography (MSOT) technologies. MSOT is purely non-invasive in nature and allows for real-time imaging of patient tissue in vivo [66,153,154]. Images gathered by MSOT show the distribution of such molecules as hemoglobin and melanin in patient tissue, due to the difference in how these molecules absorb light [155]. This distribution is indicative of disease presence and behavior in patients. A study evaluating MSOT imaging of murine colitis showed the correlation between inflammation level and concentration of oxy-hemoglobin () [66]. In a separate study, clinical trials on CD patients have shown similar results: Increased oxy-hemoglobin levels with active CD compared to remission CD [153,156]. MSOT technologies are still undergoing clinical trials for widespread use and are primarily seen in Europe. Preliminary results reveal significant potential for MSOT in rapidly diagnosing and monitoring IBD.

Multispectral optoacoustic tomography (MSOT) (A–C) and colonoscopic (D–F) images of murine colitis progression. Images were taken at t = 0, 2, and 7 days after bacterial inoculation. Yellow arrows indicate areas of inflammation correlating with colitis [67].

In summary, inflammatory conditions such as diverticulitis and IBD can be diagnosed and analyzed by a wide range of imaging modalities. Further work is required to verify the accuracy and refine the safety or comfortability of some of the mentioned modalities. Emerging technologies such as immuno-PET and MSOT could prove increasingly beneficial to imaging and diagnostic accuracy while increasing patient compliance. Since inflammation is also consistent with infection, it is important for patients with diverticulitis and IBD to be regularly monitored for alternative infectious or malignant diseases.

Abdominal and Pelvic CT

Computed tomography (CT) of the abdomen and pelvis is a diagnostic imaging test. Doctors use it to help detect diseases of the small bowel, colon, and other internal organs. It is often used to determine the cause of unexplained pain. CT scanning is fast, painless, noninvasive and accurate. In emergency cases, it can reveal internal injuries and bleeding quickly enough to help save lives.

Tell your doctor if there’s a possibility you are pregnant. Discuss any recent illnesses, medical conditions, medications you’re taking, and allergies. Your doctor may tell you not to eat or drink anything for a few hours before your exam. If you have a known allergy to contrast material, your doctor may prescribe medications to reduce the risk of an allergic reaction. You must take these medications beginning 12-13 hours prior to your exam. Leave jewelry at home and wear loose, comfortable clothing. You may need to change into a gown for the exam.

What is CT Scanning of the Abdomen/Pelvis?

Computed tomography, more commonly known as a CT or CAT scan, is a diagnostic medical imaging test. Like traditional x-rays, it produces multiple images or pictures of the inside of the body.

A CT scan generates images that can be reformatted in multiple planes. It can even generate three-dimensional images. Your doctor can review these images on a computer monitor, print them on film or via a 3D printer, or transfer them to a CD or DVD.

CT images of internal organs, bones, soft tissue, and blood vessels provide greater detail than traditional x-rays. This is especially true for soft tissues and blood vessels.

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What are some common uses of the procedure?

Doctors typically use this procedure to help diagnose the cause of abdominal or pelvic pain. They also use it to diagnose diseases of the internal organs, small bowel and colon, such as:

• infections such as appendicitis, pyelonephritis or infected fluid collections, also known as abscesses.
• inflammatory bowel disease such as ulcerative colitis or Crohn’s disease, pancreatitis or liver cirrhosis.
• cancers of the liver, kidneys, pancreas, ovaries and bladder as well as lymphoma.
• kidney and bladder stones.
• abdominal aortic aneurysms (AAA), injuries to abdominal organs such as the spleen, liver, kidneys, or other internal organs in cases of trauma.

Doctors also use CT scanning of the abdomen/pelvis to:

• guide biopsies and other procedures such as abscess drainages and minimally invasive tumor treatments.
• plan for and assess the results of surgery, such as organ transplants.
• stage, plan and properly administer radiation treatments for tumors as well as monitor response to chemotherapy.

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How should I prepare?

Wear comfortable, loose-fitting clothing to your exam. You may need to change into a gown for the procedure.

Metal objects, including jewelry, eyeglasses, dentures, and hairpins, may affect the CT images. Leave them at home or remove them prior to your exam. Some CT exams will require you to remove hearing aids and removable dental work. Women will need to remove bras containing metal underwire. You may need to remove any piercings, if possible.

Your doctor may instruct you to not eat or drink anything for a few hours before your exam if it will use contrast material. Tell your doctor about all medications you are taking and if you have any allergies. If you have a known allergy to contrast material, your doctor may prescribe medications (usually a steroid) to reduce the risk of an allergic reaction. To avoid unnecessary delays, contact your doctor well before the date of your exam.

Also tell your doctor about any recent illnesses or other medical conditions and whether you have a history of heart disease, asthma, diabetes, kidney disease, or thyroid problems. Any of these conditions may increase the risk of an adverse effect.

Women should always inform their physician and the CT technologist if there is any possibility that they may be pregnant. See the CT Safety During Pregnancy page for more information.

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What does the CT equipment look like?

The CT scanner is typically a large, donut-shaped machine with a short tunnel in the center. You will lie on a narrow table that slides in and out of this short tunnel. Rotating around you, the x-ray tube and electronic x-ray detectors are located opposite each other in a ring, called a gantry. The computer workstation that processes the imaging information is in a separate control room. This is where the technologist operates the scanner and monitors your exam in direct visual contact. The technologist will be able to hear and talk to you using a speaker and microphone.

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How does the procedure work?

In many ways, a CT scan works like other x-ray exams. Different body parts absorb x-rays in different amounts. This difference allows the doctor to distinguish body parts from one another on an x-ray or CT image.

A conventional x-ray exam directs a small amount of radiation through the body part under examination. A special electronic image recording plate captures the image. Bones appear white on the x-ray. Soft tissue, such as the heart or liver, shows up in shades of gray. Air appears black.

With CT scanning, several x-ray beams and electronic x-ray detectors rotate around you. These measure the amount of radiation being absorbed throughout your body. Sometimes, the exam table will move during the scan. A special computer program processes this large volume of data to create two-dimensional cross-sectional images of your body. The system displays the images on a computer monitor. CT imaging is sometimes compared to looking into a loaf of bread by cutting the loaf into thin slices. When the computer software reassembles the image slices, the result is a very detailed multidimensional view of the body’s interior.

Nearly all CT scanners can obtain multiple slices in a single rotation. These multi-slice (multidetector) CT scanners obtain thinner slices in less time. This results in more detail.

Modern CT scanners can image large sections of the body in just a few seconds, and even faster in small children. Such speed is beneficial for all patients. Speed is especially beneficial for children, the elderly, and critically ill – anyone who finds it difficult to stay still, even for the brief time necessary to obtain images.

For children, the radiologist will adjust the CT scanner technique to their size and the area of interest to reduce the radiation dose.

Some CT exams use a contrast material to enhance visibility in the body area under examination.

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How is the procedure performed?

The technologist begins by positioning you on the CT exam table, usually lying flat on your back. They may use straps and pillows to help you maintain the correct position and remain still during the exam.

Many scanners are fast enough to scan children without sedation. In special cases, children who cannot hold still may need sedation. Motion may cause blurring of the images and degrade image quality the same way that it affects photographs.

The exam may use contrast material, depending on the type of exam. If so, it will be swallowed, injected through an intravenous line (IV) or, rarely, administered by enema.

Next, the table will move quickly through the scanner to determine the correct starting position for the scans. Then, the table will move slowly through the machine for the actual CT scan. Depending on the type of CT scan, the machine may make several passes.

The technologist may ask you to hold your breath during the scanning. Any motion, including breathing and body movements, can lead to artifacts on the images. This loss of image quality can resemble the blurring seen on a photograph taken of a moving object.

When the exam is complete, the technologist will ask you to wait until they verify that the images are of high enough quality for accurate interpretation by the radiologist.

The CT exam usually takes just a few minutes. However, if you need to drink oral contrast, the imaging center will ask you to arrive approximately two hours prior to your scan time. Or, they may instruct you to start drinking the contrast at home prior to arriving.

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What will I experience during and after the procedure?

CT exams are generally painless, fast, and easy. Multidetector CT reduces the amount of time that the patient needs to lie still.

Though the scan is painless, you may have some discomfort from remaining still for several minutes or from placement of an IV. If you have a hard time staying still, are very nervous, anxious, or in pain, you may find a CT exam stressful. The technologist or nurse, under the direction of a doctor, may offer you some medication to help you tolerate the CT exam.

If the exam uses iodinated contrast material, your doctor will screen you for chronic or acute kidney disease. The doctor may administer contrast material intravenously (by vein), so you will feel a pin prick when the nurse inserts the needle into your vein. You may feel warm or flushed as the contrast is injected. You also may have a metallic taste in your mouth. This will pass. You may feel a need to urinate. However, these are only side effects of the contrast injection, and they subside quickly.

If you swallow oral contrast material, you may find the taste mildly unpleasant. However, most patients can easily tolerate it. If you receive an enema, you can expect to experience a sense of abdominal fullness. You may also feel an increasing need to expel the liquid. If so, be patient; the mild discomfort will not last long.

Many patients also receive an iodine-based contrast material intravenously (injected into a vein) to help evaluate blood vessels and organs such as the liver, kidneys, and pancreas.

When you enter the CT scanner, you may see special light lines projected onto your body. These lines help ensure that you are in the correct position on the exam table. With modern CT scanners, you may hear slight buzzing, clicking and whirring sounds. These occur as the CT scanner’s internal parts, not usually visible to you, revolve around you during the imaging process.

You will be alone in the exam room during the CT scan, unless there are special circumstances. For example, sometimes a parent wearing a lead shield may stay in the room with their child. However, the technologist will always be able to see, hear and speak with you through a built-in intercom system.

With pediatric patients, a parent may be allowed in the room but may need to wear a lead apron to minimize radiation exposure.

After a CT exam, the technologist will remove your intravenous line. They will cover the tiny hole made by the needle with a small dressing. You can return to your normal activities immediately.

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Who interprets the results and how do I get them?

A radiologist, a doctor specially trained to supervise and interpret radiology exams, will analyze the images. The radiologist will send an official report to the doctor who ordered the exam.

You may need a follow-up exam. If so, your doctor will explain why. Sometimes a follow-up exam further evaluates a potential issue with more views or a special imaging technique. It may also see if there has been any change in an issue over time. Follow-up exams are often the best way to see if treatment is working or if a problem needs attention.

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What are the benefits vs. risks?

Benefits

• Viewing a CT scan, an experienced radiologist can diagnose many causes of abdominal pain or injury from trauma with very high accuracy. This allows for faster treatment and often eliminates the need for additional, more invasive diagnostic procedures.
• When pain is caused by infection and inflammation, the speed, ease and accuracy of a CT exam can reduce the risk of serious complications. Such complications may include those caused by a burst appendix or an infected fluid collection and the subsequent spread of infection.
• CT scanning is painless, noninvasive, and accurate.
• A major advantage of CT is its ability to image bone, soft tissue, and blood vessels all at the same time.
• Unlike conventional x-rays, CT scanning provides very detailed images of many types of tissue as well as the lungs, bones, and blood vessels.
• CT exams are fast and simple. In emergency cases, they can reveal internal injuries and bleeding quickly enough to help save lives.
• CT has been shown to be a cost-effective imaging tool for a wide range of clinical problems.
• CT is less sensitive to patient movement than MRI.
• Unlike MRI, an implanted medical device of any kind will not prevent you from having a CT scan.
• CT imaging provides real-time imaging, making it a good tool for guiding needle biopsies and needle aspirations. This is particularly true of procedures involving the lungs, abdomen, pelvis, and bones.
• A diagnosis via CT scan may eliminate the need for exploratory surgery and surgical biopsy.
• No radiation remains in a patient’s body after a CT exam.
• The x-rays used for CT scanning should have no immediate side effects.

Risks

• There is always a slight chance of cancer from excessive exposure to radiation. However, the benefit of an accurate diagnosis far outweighs the risk involved with CT scanning.
• The radiation dose for this procedure varies. See the Radiation Dose in X-Ray and CT Exams page for more information about radiation dose.
• Women should always tell their doctor and x-ray or CT technologist if there is any chance they are pregnant. See the Safety in X-ray, Interventional Radiology and Nuclear Medicine Procedures page for more information about pregnancy and x-rays.
• Doctors do not generally recommend CT scanning for pregnant women unless medically necessary because of potential risk to the unborn baby.
• The risk of serious allergic reaction to contrast materials that contain iodine is extremely rare, and radiology departments are well-equipped to deal with reactions.
• IV contrast manufacturers indicate mothers should not breastfeed their babies for 24-48 hours after contrast material is given. However, the most recent American College of Radiology (ACR) Manual on Contrast Media reports that studies show the amount of contrast absorbed by the infant during breastfeeding is extremely low. For further information please consult the ACR Manual on Contrast Media and its references.

• Because children are more sensitive to radiation, they should have a CT exam only if it is essential for making a diagnosis. They should not have repeated CT exams unless necessary. CT scans in children should always be done with low-dose technique.

• Radiology departments tailor the radiation dose for CT scans, especially when scanning children. This helps ensure that the benefits of the scan far outweigh any possible risks from the exposure to diagnostic radiation.

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What are the limitations of CT Scanning of the Abdomen/Pelvis?

A person who is very large may not fit into the opening of a conventional CT scanner. Or, they may be over the weight limit—usually 450 pounds—for the moving table.

CT scanning of the abdomen may not be as sensitive in identifying gallstones as ultrasound of the abdomen.

Doctors prefer alternate imaging techniques such as plain films, gastrointestinal (GI) contrast exams and ultrasound for evaluating acute abdominal conditions in babies, such as vomiting or blood in stool.

For some conditions, including but not limited to some liver, kidney, pancreatic, uterine, or ovarian abnormalities, evaluation and diagnosis with MRI may be preferable to CT scanning.

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Which test, procedure or treatment is best for me?

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This page was reviewed on June, 15, 2020

90,000 What does computed tomography show? – DocDoc.ru

Computed tomography (CT) is a method of layer-by-layer scanning of a patient’s internal organs using X-rays. Unlike conventional X-ray, CT reveals the smallest changes in tissues due to better clarity of images and the ability to make “slices” with a minimum step. Today, CT is used to diagnose a wide variety of diseases, computed tomographs are improving, images are becoming more and more informative.

How is CT done?

Computed tomography is a scanner ring with a patient table in the center. During the examination, the scanner rotates, passing X-rays through the area to be examined and registering them using a sensitive matrix. The data is transferred to a computer, and layered images are obtained, which are analyzed by a doctor. The images are called tomograms, they are stored in a computer, and if necessary, they are printed. In some cases, contrast agents containing iodine are used to increase the information content of images.Depending on the organ being examined, they are administered intravenously or orally.

What is CT scanned?

Computed tomography is prescribed not in all cases – sometimes other imaging techniques are more informative. However, for some diseases, CT is the “gold standard” of diagnosis.

• Musculoskeletal system: CT is prescribed for complex fractures, joint diseases, unlike a conventional X-ray, a tomogram allows you to obtain a volumetric image of all tissues in the area of ​​damage.
• In dentistry, CT is used before surgery, in preparation for prosthetics, especially often before implantation.
• CT scan of the paranasal sinuses is the best way to diagnose sinusitis, congenital and acquired deformities of the bones of the facial skeleton.
• Computed tomography of the chest shows all structural changes in the lungs, esophagus, thoracic aorta, heart. With its help, a comprehensive study of the mediastinal organs is carried out, tumors, foci of inflammation, aneurysms and vascular deformities are detected.
• CT scan of the abdominal cavity helps in the diagnosis of neoplasms, hemorrhages, foreign bodies, and inflammatory processes. If it is impossible to make an accurate diagnosis based on the results of an ultrasound scan, CT is imperative.
• CT angiography is a highly informative method for diagnosing pathological changes in blood vessels (deformations, thrombosis, stenosis, aneurysms).

CT uses X-rays, so this diagnostic method is contraindicated during pregnancy.Contrast studies are not prescribed for severe liver, kidney, thyroid disease and for iodine allergy.

If you are worried about a health problem, sign up for a diagnosis. The success of treatment depends on the correct diagnosis.

This article is posted for educational purposes only, does not replace a doctor’s appointment and cannot be used for self-diagnosis.

23 January 2015

90,000 CT of lungs: what

shows

It is known that computed tomography of the lungs is one of the most informative diagnostic methods of research.How is CT done? What does the doctor see? What is required of a patient to undergo the procedure? These and other questions are answered by the radiologist “Clinic Expert” Irkutsk Nikita Valentinovich Monakov.

– Nikita Valentinovich, what is computed tomography (CT)?

– This is a special type of X-ray examination, the essence of which is layer-by-layer scanning of tissues by means of X-ray transmission. Based on a series of such images from a variety of sections, the doctor obtains targeted three-dimensional (3D) images of the area under study and the pathological focus.

CT is one of the most informative and highly accurate methods. It allows you to determine the localization, size of the pathological focus, to evaluate the results of treatment. Slices can be made very thin, less than a millimeter, so the doctor has very detailed information about the pathology.

CT is used both as a method of primary diagnosis and as a clarifying technique in addition to other diagnostic methods – for example, X-ray or ultrasound.

– When can a doctor refer for a CT scan of the lungs?

– CT of the lungs is prescribed to assess the volume of the upcoming surgical intervention, when assessing the effectiveness of radiation or chemotherapy, as well as in cases where other methods do not allow identifying a pathological focus.

– What does a CT scan of the lungs show?

– With the help of computed tomography, you can see the lung tissue, bronchial tree, lymph nodes, blood vessels (including the aorta, pulmonary veins). CT allows you to identify focal and diffuse processes, to determine their nature, prevalence, localization, and the severity of changes. In addition, during the study of the lungs, the condition of the esophagus, heart, and bone frame of the chest is assessed. The method allows you to measure the density of both the lung tissue itself and specifically the pathological focus located in it.The sensitivity of CT in detecting cysts, masses, and metastases in the lungs is 98 percent.

“Chest X-ray and computed tomography, bronchoscopy will be useful for detecting pulmonary echinococcosis.” Quote from the material “Attention, echinococcosis!”

– How is CT of the lungs done?

– Like any other type of tomography, this procedure is not invasive and completely painless. The patient simply lies down on a special couch, which slowly moves through the detector frame of the tomographic device.The only condition: you need to lie still. The whole procedure lasts from 5 to 20 minutes.

– How to prepare for a CT scan of the lungs?

– The patient fills out a questionnaire for possible contraindications, after which he must undress to the waist and remove all metal objects and jewelry. Before the study, it is necessary to show the direction, the results of previous studies (ultrasound, CT, MRI, radiography; films, discs, descriptions – if all this is available), medical documentation (expert opinions, extracts from medical history, outpatient cards, etc.).etc.).

– Computed tomography is based on X-rays. In this regard, the question may arise: is CT of the lungs dangerous?

– The dose of radiation received by a patient during a CT scan depends on a person’s complexion: it is the higher, the larger the patient. On new devices – for example, such as in our clinic – the radiation dosage is calculated and controlled automatically. According to children’s protocols, this load is lower. CT does not pose a danger to human health.

– Taking into account the fact that computed tomography is a radiation method of research, the question arises: how often can CT of the lungs be done without harm to health?

– This type of research is prescribed by a doctor, and only he decides whether it is necessary or not. If the doctor needs to assess the dynamics of some pathological process – the same pneumonia, then the standard provides for a second CT scan two weeks after the first.

– Are there any contraindications to CT of the lungs?

– There are no absolute contraindications.You cannot perform CT scan on pregnant and lactating women, young children. But in each specific situation, the doctor makes the decision about the need for tomography, having weighed all the risks.

– If CT is a radiation method of research, then why not do an MRI of the lungs? After all, magnetic resonance imaging is also a modern type of diagnosis, and there is no radiation exposure.

– CT is the “gold standard”. MRI is an alternative, third method for detecting lung diseases.MRI can be recommended for certain diseases, such as cystic fibrosis, pulmonary embolism, and can also be considered an alternative method for tumors and pneumonia in children, as an addition to other methods (X-ray, CT). Also, MRI can be recommended in case of ambiguous results of CT if there is a suspicion of tumor invasion into the mediastinum or pleura.

Modern MRI allows visualizing bronchiectasis, thickening of the bronchial walls, the presence of fluid levels, consolidation and destruction.

– Nikita Valentinovich, what is CT of the lungs with contrast?

– There are practically no differences from conventional CT. The patient is injected intravenously with a contrast agent, which, when examined, allows the doctor to get an even more complete picture. Before contrasting, the patient must undergo an analysis for serum creatinine, and, depending on the result, a decision is made whether he can do CT with contrast or not.

There are relative contraindications for the administration of contrast media.These are a reaction to a previously injected contrast agent, severe polyvalent allergies, asthma requiring treatment, and diabetes mellitus.

Contraindication to CT scan with contrast enhancement is hyperthyroidism, thyrotoxicosis, treatment with radioactive iodine.

CT scan with contrast enhancement can be performed if the patient has seasonal allergies, mild and moderate reactions to various allergens (including iodine, seafood), asthma without exacerbation.

Interviewed by Igor Chichinov

For reference

Monakov Nikita Valentinovich

In 2012Graduated from Irkutsk State Medical University, Faculty of Pediatrics.

In 2013-2014 – internship in radiology at the State Budgetary Educational Institution of Higher Professional Education, ISMU.

2016 – professional retraining in ultrasound diagnostics of the State Budgetary Educational Institution of Higher Professional Education IGMAPO Irkutsk.

2018 – advanced training in radiology with the course of computed tomography of the FBGU NMITs them. V. A. Almazov, St. Petersburg.

2018 – advanced training in MRI, ChUDPO IPKMK Voronezh.

90,000 Pulmonologists named indications for CT of lungs in case of suspected COVID-19 :: Society :: RBC

“For this, there must be appropriate indications – for example, a person has a long, more than 4–5 days, the temperature is above 38–39 degrees. And during examination, listening, the doctor discovers some changes in the lungs, changes in the respiratory function – then he can prescribe a CT scan, ”he said.

According to a pulmonologist, professor of the Department of Phthisiology and Pulmonology, Faculty of Medicine, Moscow State University of Medicine and Dentistry.AI Evdokimov Sergei Babak, computed tomography allows you to “see” the structure of the lungs.

Read on RBC Pro

“Indications for CT – when we want to understand whether there are structural changes in the lungs, in the bronchi, a vascular component, whether there is inflammation in the lungs, whether there are oncological manifestations. There are changes specific to the viral lesion of the lungs, they are also clearly visible on CT, ”the doctor explained.

During the day 37 thousand.: how the COVID epidemic is developing in Russia. Infographics

At the same time, the patient cannot be diagnosed only on the basis of computed tomography data, the professor emphasized. “Any diagnostic method is meaningless without the presence of symptoms. The combination of symptomatology with diagnostic data improves the accuracy of the diagnosis. It is impossible to make a diagnosis only with the help of functional diagnostics, ”Babak said.

He noted that this procedure will be difficult for patients who, for whatever reason, cannot be in a horizontal position, cannot take a deep breath, suffer from claustrophobia. In addition, CT scans should not be performed on pregnant and lactating women.

Earlier, the chief specialist in radiation and instrumental diagnostics of the Russian Ministry of Health, Professor Igor Tyurin, urged Russians not to do computed tomography “just in case.” According to him, this procedure is indicated for patients with severe clinical symptoms of a respiratory infection (high fever, shortness of breath) and patients with ARVI symptoms who have serious risk factors (severe excess weight, severe diabetes, severe heart failure).

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Source: JHU, Federal and Regional Virus Control Headquarters

90,000 3D diagnostics (CT scan of teeth) will find everything!

Do you need a complete high-quality examination before implantation, endodontic treatment or complex tooth extraction? 3D Diagnostics Shows Everything!

Computed tomography of teeth is necessary for the diagnosis of the dentition, various inflammations, cysts, fractures, diagnosis of bone loss.

3D image is much more accurate and detailed than 2D images. Thanks to CT, the doctor will be able to see each tooth from several angles, which increases the information content and allows for a more effective treatment plan. In this way, you can better identify the problem and start solving it.

Two-dimensional X-rays (panoramic X-rays) are sufficient for general orientation. However, the lack of a third dimension can be critical in terms of a complete diagnosis.

When is it desirable to have a 3D dental scan?

1. Implantation – Computed tomography of teeth is very important for assessing bone bone, assessing bone quality, choosing the appropriate type, implant size, direction and site of insertion. A computed tomography scan is an important condition for the safe insertion of a dental implant.
2. Surgical extraction of wisdom teeth. In these cases, a CT scan examines the exact location of these teeth, which significantly reduces the risk of root damage to healthy teeth.
3. Endodontic treatment . CT scan allows you to examine in detail the location of the root canals – the anatomy of the internal space of the tooth, the number and course of individual root canals, the presence of resorption, perforation, etc.
4. Periodontics. The CT scan provides valuable information about the extent of damage to the bone around the teeth. This allows you to accurately determine the treatment plan treatment.
5. Other less common causes include diagnostics of foreign bodies, tumors, and jaw disease.
6. Computed tomography can detect even small and hidden caries .
7. Final cost . CT scan will allow the dentist to draw up a detailed treatment plan and calculate the exact cost. Thanks to the 3D image, the cost of the treatment will not come as a surprise to you.

The modern dental clinic “Luxar” invites you to undergo dental tomography.
In our clinic you will find a true European level of service.A staff of experienced doctors and the most modern medical equipment will allow everyone to receive timely qualified assistance!

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90,000 Russian diagnostician – about computed tomography and other methods for determining COVID-19 – RT in Russian

Computed tomography is becoming the main diagnostic tool for COVID-19, since the accuracy of this method is 97-98%. This was stated in an interview with RT by the chief specialist in radiation and instrumental diagnostics of the Moscow Healthcare Department and the Russian Ministry of Health in the Central Federal District, director of the Diagnostic and Telemedicine Center, Professor Sergei Morozov.According to him, the whole procedure, together with the disinfection of the equipment, takes no more than half an hour. At the same time, he clarified that various X-ray and even ultrasound machines are suitable for determining coronavirus pneumonia.

– Sergey Pavlovich, now, at the initiative of the Ministry of Health of Russia, the method of computed tomography, and not laboratory testing, is becoming the main diagnostic tool for COVID-19. Why?

– Coronavirus infection must be treated without waiting for the test result.This was obvious to specialists, and is now approved in the methodological recommendations of the Ministry of Health of Russia – to identify signs of pneumonia by computed tomography.

Laboratory testing, PCR and other tests are necessary to identify the virus, that is, to determine the causative agent of the disease. But the test can show a negative result because it is imperfect or was performed incorrectly. At the time when the material for testing is taken from the nasopharynx, the virus could already descend into the lungs, and then it cannot be identified.In addition, the detection of a virus in a patient does not establish a method of treatment.

• Professor Sergey Morozov, Chief Specialist in Radiation Instrumental Diagnostics of the Moscow Healthcare Department and the Russian Ministry of Health for the Central Federal District, Director of the Diagnostic and Telemedicine Center
• © Official website of the Mayor of Moscow

– Are we talking about determining the presence of a coronavirus or just identifying pneumonia caused by it?

– Actually, we are not treating the virus itself.The existing regimens, of course, include antiviral drugs, but they are largely aimed at maintaining the body’s readiness to cope with a viral infection.

The treatment algorithm is determined by the clinical picture, severe symptoms, the state of the body’s vital activity.

– It turns out that it is not very important for doctors what kind of infection caused pneumonia: coronavirus or some other?

– That’s right. In the current epidemiological season, other infections are unlikely to cause viral pneumonia, and they are treated in approximately the same way.In addition, computed tomography often shows a greater severity of changes than clinical manifestations. Outwardly, the patient’s condition seems to lag behind, because the body copes up to a certain point.

But if the so-called frosted glass is found on the CT scan results, that is, seals of more than 5 cm, then we understand that the patient will soon become worse. And we will be able to start more active treatment at an early stage, and not wait until he really gets sick.

– Who and how came up with the idea of ​​diagnosing COVID-19 using CT?

– The experience of using computed tomography for the diagnosis of coronavirus pneumonia was also used by Chinese colleagues.We knew this from international publications as well. Naturally, we communicate a lot with colleagues from different countries and see what is happening.

Also on the topic

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The new coronavirus’s strategy is forcing it to reduce virulence and become less dangerous to its host. About this in a conversation with…

– Could CT be the main diagnostic tool? How accurate is it? Are there other hardware-based ways to detect COVID-19?

– The computed tomography method is very accurate, its sensitivity is somewhere between 97-98%. For comparison, for PCR tests this figure is about 70%. In this case, of course, CT can be safely combined with any other methods. There is also X-ray diagnostics, it is absolutely necessary and expedient, but it is more difficult to interpret.But if there is not enough CT equipment or the number of incoming patients is so large that they simply do not have time to do computed tomography, you can resort to X-ray equipment.

Now in Italy, for example, ultrasound is also used. It is generally believed that an ultrasound of the lungs is not done. Of course, in this way it is impossible to fully see the organ, but it is possible to assess the necessary areas – to see the posterior basal sections.

– Could it be that neither tests nor computed tomography show infection – and the sick person will be released from quarantine?

– Computed tomography somewhere in the first three days of illness may not show changes in the lungs, therefore, for screening, that is, the initial examination of patients without symptoms, CT diagnostics cannot be used.In this case, a situation may indeed arise when the manifestations of the virus were not found, and the next day a person will have a typical picture of the disease.

• Various X-ray and even ultrasound machines are suitable for identifying patients with coronavirus pneumonia.
• RIA News
• © Pavel Lvov

– Is viral pneumonia dangerous, for example, for children? Judging by the information about the main risk groups, should CT scan be done first of all for the older generation?

– Computed tomography can be done for both children and adults.Coronavirus disease, indeed, now affects more older people, starting at the age of 40, but it also happens in young people. In 80% of cases, COVID is mild.

Difficulties arise when a person already has some kind of background disease: diabetes, heart failure, oncology. Because the body is already in a tense state, resources are scarce, and then there is a virus. So the question is no longer about age, but about the clinical manifestations of the disease.

– Remind them, please.

– With viral pneumonia, hypoxemia appears – a decrease in the level of oxygen in the blood. Alarming symptoms: persistent temperature of 38.5 and higher for three days or longer, respiratory failure, when, for example, it is difficult to climb stairs, slight cyanosis of the lips or nail plates.

This virus creates a very heavy load on the body, and against this background, other diseases can appear. Bacterial pneumonia can join viral pneumonia, chronic diseases can be complicated or thrombus formation can begin.

– How many CT machines are there in the country (and in Moscow in particular)? Are they all suitable for solving the assigned tasks? Is additional training required?

– There are statistics on Moscow polyclinics, where the situation is the most tense. To date, the total number of computed tomography scanners in the city’s polyclinics is 49, all of which allow examining the lungs.

The research methodology of working on a computed tomography scanner is simple, we are now attracting specialists in mammography, fluorography, MRI, and X-ray studies.Assistants are allocated to laboratory assistants – nursing staff and even students in the framework of industrial practice. Many specialists undergo additional training in working with CT.

• Alarming symptoms in which CT diagnostics of the lungs is prescribed: persistent temperature 38.5, respiratory failure, slight cyanosis of the lips or nail plates
• RIA News
• © Alexey Sukhorukov

– How is this training organized?

– Our center began broadcasting various training programs, webinars on training specialists for the use of computed tomography a few weeks ago.In the first two days alone, 2,000 specialists were registered, and not only radiologists. The free computed tomography analysis course lasts about 18 teaching hours. You can quickly and remotely learn how to interpret these studies and understand it very well.

– Tell us how the work of CT cabinets is organized in an epidemic? Will the diagnostic center become a hotbed of infection?

– According to the new recommendations, specialists are provided with personal protective equipment.Patients with suspected COVID are sent through a separate entrance to the computed tomography room.

The CT room is divided into three isolated areas to minimize the risk of cross-contamination. An assistant helps to place the patient on the device. The technician from the control room starts the diagnostics, and the doctor from the other room describes the study. After each examined person, the equipment and work surfaces are sanitized. Even simple adherence to the normal sanitary and epidemiological regime can minimize the risks of infection.

This is shown by the experience of “covidarium” – specialized hospitals for patients with COVID-19. Laboratory assistants, radiologists, and doctors have been working there with “covid” patients for a month, but they do not get infected.

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– How long does such a procedure take, taking into account the sanitary and epidemiological treatment?

– The examination is fast, the scan itself takes less than a minute. Taking into account the placement and removal of the patient from the table – 10 minutes on average. Plus the interpretation of the results. The radiologist can assess the situation very quickly, up to 15 minutes. Minimal cleaning of contact surfaces after each patient. A total of 20-30 minutes is obtained for each patient. After receiving several patients, the current cleaning is carried out according to the schedule.

– What about people who are prescribed CT in connection with other diagnoses? With those who stood in line for this check at this time?

– Nowadays, medical support is no longer sufficient for all patients. And despite the fact that now the examination and diagnosis of “covid” patients are carried out separately from the rest, those who do not have an urgent need for immediate treatment, it is better to postpone it. But in general, of course, the situation creates very high risks for patients and a great burden on the healthcare system.Some organizations have already decided on round-the-clock operation of computed tomography rooms in polyclinics.

– On what conditions can you undergo CT diagnostics on your own initiative?

– In state organizations, computed tomography is now performed for all patients with a temperature above 38.5. And treatment is prescribed, and drugs are given free of charge to everyone who is prescribed. The funds of the MHI fund are purposefully used for this. There are, of course, private medical organizations that continue to work and also provide the possibility of examinations, but on a commercial basis.

Computed tomography or test? How to “catch” the coronavirus

04.24.2020

With testing for coronavirus, the situation is not entirely clear: on the one hand, there are more test systems, different types of tests appear that determine whether a person is infected, whether he has had the “corona” (antibody test) or not. On the other hand, there are many questions about their reliability.

With testing for coronavirus, the situation is not entirely clear: on the one hand, there are more test systems, different types of tests appear that determine whether a person is infected, whether he has had the “corona” (antibody test) or not.On the other hand, there are many questions about their reliability.

The most common testing method today is PCR, a sputum sample is taken from the patient and the presence or absence of the virus is determined. You can read more about the method in the article “How to check for coronavirus: an overview of Russian (and not only) tests.” However, experts and doctors complain: up to 30% of tests give a false negative or false positive result.

“During PCR testing, underdiagnosis is noted, that is, PCR gives a negative result, but the person actually has COVID-19.Therefore, when making a diagnosis, they are guided by the epidemiological history of a person and if he had contact with the sick, then there is a high probability that he has COVID, ” – said Oleg Grishin, a pulmonologist, doctor of medical sciences, leading expert of the Infrastructure Center Helsnet NTI .

Now the diagnosis of COVID-19 is made on the basis of the results of computed tomography and the clinical picture of the disease, since CT can reveal the most dangerous complication of coronavirus – pneumonia.

On CT scans, signs of viral pneumonia are clearly visible, distinguishing it from other types of pneumonia – opacity in the lungs in the form of “frosted glass”. This is not a specific sign, but in combination with other symptoms, it makes it possible to identify a threatening condition in time.

Late detection of pneumonia ends with artificial ventilation.

How is CT diagnosis different from tests?

A person who is not familiar with the methods of medical diagnostics may have a question: how in the end to understand whether I am sick or not, is it worth doing the test or should I immediately run to a private clinic for CT of the lungs?

We answer.

PCR diagnostics determines the presence of infection, however, disease and infection are different things. Only half of those infected develop the disease. Of those who get sick, pneumonia also develops not in everyone, but only in every third person. Half of people who test positive for COVID-19 have no symptoms at all. That is, PCR diagnostics does not detect a disease, but the presence of a virus in the body.

“For the laboratory, the patient and the infected do not differ fundamentally.In an infected person, the body may not be susceptible to this infection. At the same time, he may be a carrier for some time, or may not be one ”, – Oleg Grishin , leading expert of the Helsnet NTI Infrastructure Center.

If a person is infected, but not sick, he cannot have pneumonia, therefore it is pointless to do CT.

If a person has ARVI symptoms, then with a probability of 60–70% he will not develop pneumonia. In this case, CT will also show nothing.However, in the remaining 30%, pneumonia can occur and for its early diagnosis, the most effective method is CT.

How is coronavirus pneumonia different from common pneumonia?

Distinctive features of viral pneumonia are considered to be a rapidly growing course and rapidly increasing shortness of breath against the background of the usual symptoms of ARVI.

“Symptoms of acute respiratory viral infections can appear for five to six days without a particularly high temperature, without any signs of a severe course, and then the condition worsens sharply.Boris Johnson, Prime Minister of Great Britain, is a classic example of this course of the disease. In the beginning, he had the usual signs of SARS, within a week he was tested, PCR confirmed the presence of the virus, but Johnson was at home because he felt good. Then, within one or two days, the condition worsened and shortness of breath appeared. This is the basis for CT scan and transfer to the hospital “, – said Grishin .

Unlike bacterial pneumonia, it is difficult to “hear” viral pneumonia with a phonendoscope in the first 1-2 days.This is typical for any viral pneumonia, including the influenza virus, and such a development of the disease has always been a problem for mankind.

“A doctor can come to a patient, register a high temperature, but he does not hear problems in the lungs with his ear. He leaves without revealing viral pneumonia, and after a few hours the disturbances in the lungs intensify, you can hear it through the phonendoscope, but the doctor is no longer nearby, ” – Oleg Grishin , leading expert of the Helsnet NTI Infrastructure Center.

Therefore, it is so important to see a doctor in a timely manner if something went wrong.

The

CT scan of the chest provides an image of the patient’s lungs and helps doctors calculate the so-called “corona score” – the percentage of lung volume infected with a disease. Computed tomography analysis technology based on deep learning algorithms is becoming a promising direction for diagnostics. It helps to identify coronavirus pneumonia with an accuracy of about 96%, and the entire test takes 3-4 seconds.It takes a person 60 times longer to make a diagnosis, so the use of artificial intelligence and machine learning methods in CT diagnostics is becoming critically important. We will tell you more about how the world’s leading companies are introducing artificial intelligence into the daily practice of making diagnoses.

Source: VC.ru

“You can’t wait for the PCR result – you need to heal faster” | Articles

Significant changes have been made to the diagnosis of coronavirus.Now the disease will be determined by the clinical picture and the results of computed tomography, without waiting for the results of PCR . This will allow you to quickly help those who have already begun to develop pneumonia. The chief specialist in radiation and instrumental diagnostics of the Moscow Healthcare Department and the Russian Ministry of Health in the Central Federal District, Director of the Diagnostic and Telemedicine Center, Professor Sergei Morozov told Izvestia about this. According to him, now the Moscow Clinical Committee is making appropriate adjustments, they will be included in federal documents.Earlier this approach was announced by the Minister of Health Mikhail Murashko. In Moscow, polyclinics were connected to CT scan for ARVI patients. Until lunchtime, they will conduct a regular appointment, and then until one in the morning they will be engaged in diagnostics of the coronavirus.

– Why is the approach to the diagnosis of coronavirus changing now?

– PCR analysis often does not work due to the fact that material is taken from the patient from the nasopharynx. But if a person is at the stage of the disease, when the infection has already dropped lower, there may not be a virus in the nasopharynx, it is necessary to look for it in the bronchi .In addition, the quality of analysis may suffer under the enormous laboratory workload. In addition, obtaining a PCR result takes a lot of time – at least two days. Often a negative result comes, while the patient may have manifestations of viral pneumonia.

A few days ago in such a situation it was impossible to start treating a patient with specific drugs that help specifically with viral pneumonia. Clinicians assumed that since a specific virus was not identified, treatment regimens for it could not be used.Now it has become clear that in the face of an increase in the number of cases, it is impossible to wait for the PCR result – it is necessary to heal faster than . Two days later, a person may have severe respiratory failure, which will require resuscitation treatment.

Photo: press service of the Diagnostic and Telemedicine Center

Computed tomography (CT) of the lungs

The diagnosis can be made immediately – based on the results of computed tomography (CT) . It is performed in patients with a clinical picture of ARVI.The diagnosis is confirmed if “frosted glasses” are detected on both sides – areas of small compaction of lung tissue (differ from dense infiltration of bacterial pneumonia). With a mild course at an early stage, these are separate zones of “frosted glass” in the posterior parts of the lungs, mainly in the lower lobes. As the disease progresses, these zones become larger, denser, and a bacterial infection may join. And then complications appear – for example, pleural effusion (excess fluid in the pleural cavity).

If the patient shows minimal changes on CT, he can be treated at home. If the changes are more pronounced, and this often overtakes clinical manifestations (a person may still feel good), it is necessary to be hospitalized and start active therapy.

– Approximately what percentage of patients require CT?

– Computed tomography should be done for those who have a fever above 38 ° C and shortness of breath.

And if the patient’s temperature drops in the hospital, a study can be carried out to make sure that there is no damage to the lungs, and the person can be discharged on this basis, despite the fact that PCR may still be positive.

– In approximately what percentage of cases will a CT scan be required?

– I think up to 30% of patients who have ARVI. These are not even all patients with acute respiratory viral infections, but those whose disease is progressing and whose temperature is above 38 ° C.

– Will the clinical guidelines be changed due to the new approach to diagnosis?

– Yes, now the Moscow Clinical Committee is making appropriate adjustments. They will also be included in federal documents – methodological recommendations, and all this is happening quite quickly, because the situation requires quick decisions.

Photo: RIA Novosti / press service of the University named after M.I. Sechenov

– Is this approach to diagnosis reflected in the recently published manual of the Ministry of Health for the treatment of coronavirus?

– Yes, it contains the diagnosis by computed tomography.But so far it has been noted that this is a probabilistic method. Confirmation of the diagnosis is still possible only with the help of PCR. These recommendations will change , an indication will appear that a diagnosis based on the patient’s symptoms (fever, cough, muscle pain) and computed tomography can be considered clinically confirmed.

– Can a CT scan give a false result?

– According to international data, the accuracy of the study is 97–98% . A negative result with CT can be only in the very initial stage of the disease in the mildest forms.

The specificity of the study is slightly lower: CT can mistake another viral pneumonia for coronavirus, but in this case, the treatment tactics will not differ much.

– Does the interpretation of CT results depend on who interprets them?

– No. Computed tomography – digital standardized examination . The main thing is to indicate what the thickness of the slice should be for diagnostics, and then you can quite calmly interpret the results.Moreover, they are archived electronically and can be sent for remote analysis to any doctor.

– How many CT machines are there in Moscow polyclinics? It’s enough?

– There are many devices in Moscow. 49 – in polyclinics. In addition, all hospitals are equipped with CT scanners. This is enough if research is carried out according to the indications, and not everyone in a row. The main deficit in the regions, this will be difficult.

– In some clinics and hospitals, old devices.Do they have normal sensitivity?

– Yes. Even older machines – 4-slice, 16-slice – can be used perfectly.

Photo: RIA Novosti / Alexander Kondratyuk

– How will the work of the polyclinic change with a new approach to the diagnosis of coronavirus?

– At the entrance to the polyclinic, a clean disposable mask will be put on the patient and taken to the examination through a separate passage. The areas where the assistant laboratory assistant, laboratory assistant and doctor work will be separated.The doctor will immediately make a conclusion on the study. The experts of the teleradiological center will help him remotely. If mild manifestations of viral pneumonia are detected (the PCR result may be negative), the patient will be consulted by a therapist who will prescribe specific treatment and send the person home. If a patient shows signs of moderate or severe coronavirus pneumonia, the general practitioner immediately gives a referral for hospitalization and calls an ambulance.

– How will polyclinics cope with this new workload?

– They will work until 1 am.In the morning, polyclinics will conduct a regular appointment, and in the afternoon they will receive patients with ARVI. After that, from one in the morning until seven in the morning, a complete sanitization is carried out, and then the polyclinic again works as usual.

– Will private medical organizations be involved in CT diagnostics on the basis of compulsory medical insurance?

– These possibilities are under discussion.

– How often does a coronavirus infection develop into pneumonia?

– We started performing CT in polyclinics from April 8th. So far, about 500 patients undergo chest examination every day, and somewhere in 10% viral pneumonia is detected – most likely coronavirus.