Does ct scan show inflammation. Abdominal CAT Scan for Children: Comprehensive Guide for Parents

10.11.197626.10.2021 by alexxlab

What is an abdominal CAT scan. How is it performed on children. What are the reasons for conducting this procedure. What should parents expect during and after the scan. How safe is a CAT scan for children.

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Understanding Abdominal CAT Scans in Pediatrics

An abdominal CAT (Computed Axial Tomography) scan, also known as a CT scan, is a sophisticated imaging technique that provides detailed cross-sectional images of a child’s internal organs. This non-invasive procedure utilizes specialized X-ray equipment to capture multiple images from various angles, which are then processed by a computer to create comprehensive 3D visualizations of the abdominal region.

The scan is performed by a trained technician and typically takes between several minutes to 45 minutes, depending on various factors such as the child’s age, the need for contrast solution, and whether sedation is required. The actual radiation exposure time is significantly shorter than the total procedure duration.

How does a CAT scan differ from a regular X-ray?

While both CAT scans and X-rays use radiation to create images, CAT scans offer several advantages:

They provide more detailed, three-dimensional images
They can differentiate between various types of tissues
They allow for better visualization of soft tissues and blood vessels
They can detect smaller abnormalities that might be missed on a regular X-ray

Reasons for Conducting an Abdominal CAT Scan in Children

Pediatricians may recommend an abdominal CAT scan for various reasons, primarily to diagnose or monitor conditions affecting the abdominal organs. Some common indications include:

Detecting signs of inflammation or infection
Identifying injuries following trauma
Diagnosing diseases of the liver, spleen, kidneys, bladder, stomach, intestines, pancreas, or adrenal glands
Evaluating blood vessels and lymph nodes in the abdomen
Investigating persistent abdominal pain
Assessing the effectiveness of treatments for previously diagnosed conditions

Is an abdominal CAT scan always necessary for diagnosing abdominal issues in children? Not always. The decision to perform a CAT scan is made by healthcare professionals based on the child’s specific symptoms, medical history, and the results of other diagnostic tests. In some cases, alternative imaging methods like ultrasound or MRI might be considered first, especially when trying to minimize radiation exposure.

Preparing Your Child for an Abdominal CAT Scan

Proper preparation is crucial for ensuring the best possible results from an abdominal CAT scan. Here are some key points to keep in mind:

Fasting Requirements

Your child may need to fast for several hours before the scan. This is particularly important if:

Sedation will be used during the procedure
A contrast solution needs to be administered

Fasting helps ensure that the stomach is empty, which can improve image quality and reduce the risk of complications if sedation is required.

Clothing and Accessories

Your child will likely be asked to remove all clothing and accessories and change into a hospital gown. This is because metal objects such as buttons, zippers, or jewelry can interfere with the imaging process.

Contrast Solution

In some cases, a contrast solution may be necessary to highlight specific areas of the body during the scan. This can be administered in two ways:

Intravenously (IV): A quick pinprick to insert the IV line, followed by a painless injection of the contrast solution
Orally: Your child may be asked to drink a special fluid before the procedure. While some children may not like the taste, it can often be flavored to make it more palatable

Special Considerations for Pregnant Teens

If your daughter is pregnant or there’s a possibility of pregnancy, it’s crucial to inform the technician or doctor before the scan. While there’s a small risk that radiation from the CAT scan could harm a developing fetus, necessary precautions can be taken if the scan is deemed essential.

The Abdominal CAT Scan Procedure: What to Expect

Understanding the step-by-step process of an abdominal CAT scan can help alleviate anxiety for both parents and children. Here’s what typically happens during the procedure:

Your child will be positioned on a narrow table, usually lying on their back, side, or stomach.
If contrast solution is required, it will be administered either through an IV line or orally.
The technician will position your child correctly and then move to an adjoining room to operate the machine.
The table will move through the doughnut-shaped CAT machine.
The technician will communicate with your child through an intercom system.
Older children may be asked to hold their breath for a few seconds at a time to prevent image blurring.
The machine will make whirring and buzzing sounds as it captures images.

Can parents stay with their child during the CAT scan? In most cases, parents can stay in the room until the scan begins. After that, you’ll either join the technician in the outer room or wait in a designated area. If you remain with the technician, you’ll be provided with a lead apron for protection.

Sedation in Pediatric Abdominal CAT Scans

Sedation may be necessary for some children, particularly infants and young kids who might have difficulty lying still for the duration of the scan. Sedation medications are typically administered through an IV line and help keep the child comfortable and motionless during the procedure.

When is sedation required for a CAT scan?

Sedation might be recommended in the following situations:

For very young children who can’t understand instructions to stay still
For children with anxiety or fear about the procedure
When the scan needs to be particularly detailed and even slight movement could blur the images
For longer scanning procedures

It’s important to note that if sedation is used, it will take some time for the effects to wear off after the scan is completed.

Post-Scan Procedures and Getting Results

After the CAT scan is complete, the following steps typically occur:

Your child will be asked to wait briefly while the technician reviews the image quality.
If any images are blurred, parts of the scan may need to be repeated.
If sedation was used, your child will be monitored until the effects wear off.
A radiologist will analyze the CAT scan images and prepare a report.
The radiologist’s report will be sent to your child’s doctor.
Your child’s doctor will discuss the results with you and explain their implications.

How long does it take to get CAT scan results? Results are typically available within 1-2 days. However, in emergency situations, results can be expedited. It’s important to note that in most cases, results cannot be given directly to the patient or family at the time of the test.

Safety Considerations and Radiation Exposure in Pediatric CAT Scans

While CAT scans are generally considered safe, they do involve exposure to ionizing radiation. This naturally raises concerns for many parents. Here’s what you need to know about the safety aspects of abdominal CAT scans for children:

Radiation Exposure

CAT scans use more radiation than regular X-rays. However, the amount used in a single CAT scan procedure is not considered dangerous. Nevertheless, it’s important to understand that any exposure to radiation carries some risk to the body.

Balancing Risks and Benefits

Healthcare providers always weigh the potential benefits of a CAT scan against the risks of radiation exposure. They follow the principle of ALARA (As Low As Reasonably Achievable) when it comes to radiation dose.

Minimizing Radiation Exposure

Several strategies are employed to minimize radiation exposure in pediatric CAT scans:

Using child-specific, low-dose protocols
Limiting the scan area to only what’s necessary
Avoiding repeated scans unless absolutely necessary
Considering alternative imaging methods when possible

Long-term Effects

While the long-term effects of medical radiation exposure are still being studied, the immediate benefits of an accurately diagnosed and treated condition typically outweigh the small potential long-term risks associated with a CAT scan.

Are there alternatives to CAT scans that don’t involve radiation? In some cases, yes. Depending on the specific medical concern, alternatives such as ultrasound or MRI might be considered. These imaging techniques don’t use ionizing radiation. However, they may not always provide the same level of detail as a CAT scan, particularly for certain abdominal conditions.

Addressing Common Concerns and Questions About Pediatric Abdominal CAT Scans

Parents often have numerous questions and concerns when their child is scheduled for an abdominal CAT scan. Here are some common queries addressed:

Is the procedure painful?

The CAT scan itself is painless. Your child won’t feel anything as the images are being taken. However, if an IV is required for contrast solution, there may be a brief moment of discomfort during insertion.

How can I prepare my child emotionally?

Explain the procedure in age-appropriate terms. Emphasize that it’s quick and painless. For younger children, you might describe it as a special camera that takes pictures of the inside of their body. Older children might appreciate more detailed explanations about how the machine works.

What if my child is claustrophobic?

Modern CAT scanners are less enclosed than older models, which can help reduce anxiety. If your child is very anxious, talk to your doctor about the possibility of using mild sedation or anti-anxiety medication.

Can I stay with my child during the scan?

In most cases, you can stay with your child until the scan begins. After that, you’ll need to leave the room due to radiation exposure, but you can often watch through a window and communicate via intercom.

How often can a child safely undergo a CAT scan?

There’s no definitive limit, as the need for scans depends on the individual medical situation. However, doctors always aim to minimize radiation exposure by only ordering scans when necessary and exploring alternative imaging options when possible.

What are the potential side effects?

Most children experience no side effects from a CAT scan. If contrast material is used, some children might experience brief side effects such as a metallic taste in the mouth, nausea, or a warm sensation throughout the body. Allergic reactions to contrast material are rare but possible.

Technological Advancements in Pediatric CAT Scanning

The field of medical imaging is continually evolving, with new technologies and techniques emerging to improve the safety and efficacy of CAT scans, particularly for pediatric patients. Some recent advancements include:

Low-Dose Protocols

Manufacturers have developed specialized low-dose protocols for pediatric patients, significantly reducing radiation exposure without compromising image quality.

Iterative Reconstruction Techniques

These advanced image processing methods allow for high-quality images to be produced from lower radiation doses.

Faster Scanning Times

Newer machines can complete scans more quickly, reducing the need for sedation in young patients and minimizing motion artifacts.

3D and 4D Imaging

Advanced software can create detailed three-dimensional images and even show motion over time (4D imaging), providing more comprehensive information to clinicians.

Dual-Energy CT

This technique uses two different energy levels to provide additional information about tissue composition, potentially reducing the need for multiple scans or additional tests.

How do these advancements benefit pediatric patients? These technological improvements not only reduce radiation exposure but also enhance diagnostic accuracy, potentially leading to more precise treatments and better outcomes for young patients.

As medical imaging technology continues to advance, we can expect even more improvements in the safety and efficacy of pediatric CAT scans. Parents should feel encouraged to discuss these advancements with their healthcare providers and ask about the specific technologies used in their child’s imaging procedures.

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.