What is a CT scan. How does it work. Why are CT scans performed. What are the benefits and risks of CT scans. How to prepare for a CT scan. What happens during and after a CT scan. How do CT scans compare to other imaging techniques.

Understanding CT Scans: The Basics of Computed Tomography

A CT scan, short for Computed Tomography scan, is a powerful diagnostic imaging technique that combines X-ray technology with advanced computer processing to create detailed cross-sectional images of the body. This non-invasive procedure allows medical professionals to visualize internal structures with remarkable clarity, providing invaluable insights into a patient’s health.

How does a CT scan work? The process involves an X-ray tube rotating around the patient’s body, emitting beams that pass through the tissues at various angles. Detectors on the opposite side of the body measure the amount of radiation absorbed, and sophisticated computer algorithms reconstruct these measurements into detailed images.

Key Features of CT Scans:

• High-resolution imaging of bones, soft tissues, and blood vessels
• Ability to create 3D reconstructions of internal structures
• Quick scan times, often lasting only a few minutes
• Non-invasive nature, requiring no surgical intervention

Can CT scans detect all types of medical conditions? While CT scans are incredibly versatile, they are particularly effective in diagnosing certain conditions. These include:

1. Bone and joint problems
2. Lung and chest issues
3. Cancer detection and staging
4. Cardiovascular diseases
5. Internal injuries from trauma

However, it’s important to note that some conditions may require alternative imaging techniques for optimal diagnosis.

The Role of Contrast Agents in CT Imaging

Contrast agents play a crucial role in enhancing the visibility of specific structures during CT scans. These substances are designed to temporarily alter how X-rays interact with the body, providing greater detail and clarity in the resulting images.

When are contrast agents used in CT scans? Contrast media are typically employed when:

• Examining blood vessels or vascular structures
• Evaluating organ function and perfusion
• Detecting and characterizing tumors
• Assessing inflammation or infection

The decision to use contrast is made based on the specific diagnostic goals and the patient’s individual health considerations.

Types of CT Contrast Agents:

1. Iodine-based contrast (administered intravenously)
2. Barium-based contrast (taken orally for gastrointestinal studies)
3. Air or carbon dioxide (used as negative contrast in certain procedures)

Are there risks associated with contrast agents? While generally safe, some patients may experience allergic reactions or other complications. It’s crucial to inform your healthcare provider of any previous reactions to contrast media or existing medical conditions, particularly kidney problems, before undergoing a contrast-enhanced CT scan.

Preparing for Your CT Scan: Essential Steps and Considerations

Proper preparation is key to ensuring a successful CT scan and obtaining the most accurate results. The specific requirements may vary depending on the type of scan and whether contrast agents will be used.

General Preparation Guidelines:

• Inform your doctor of any medications you’re taking
• Discuss any allergies, particularly to iodine or contrast agents
• Mention if you’re pregnant or think you might be
• Follow any fasting instructions provided by your healthcare team
• Wear comfortable, loose-fitting clothing without metal fasteners

How long do I need to fast before a CT scan with contrast? For most contrast-enhanced CT scans, you’ll be asked to avoid eating for 3-4 hours prior to the procedure. However, clear liquids are often permitted and even encouraged to ensure proper hydration.

Should I stop taking my regular medications before a CT scan? In most cases, you can continue taking your prescribed medications as usual. However, certain medications, particularly those affecting kidney function or blood sugar levels, may need to be adjusted. Always consult with your healthcare provider for personalized guidance.

The CT Scan Procedure: What to Expect During Your Examination

Understanding the CT scan process can help alleviate anxiety and ensure a smooth experience. While specific procedures may vary, most CT scans follow a similar general pattern.

Steps in a Typical CT Scan:

1. Removal of metal objects and changing into a hospital gown if necessary
2. Positioning on the CT scanner table
3. Administration of contrast agent (if required)
4. Table movement into the CT scanner’s circular opening
5. Brief periods of breath-holding as instructed by the technologist
6. Completion of scan, usually lasting 10-30 minutes

Is a CT scan painful? The CT scan itself is painless. You may feel slight discomfort from lying still on the table or a warm sensation if contrast is injected. Some patients experience mild claustrophobia, but the open design of modern CT scanners helps minimize this issue.

What happens after the CT scan is complete? Once the scan is finished, you can usually resume normal activities immediately. If contrast was used, you’ll be advised to drink plenty of fluids to help flush it from your system. The images will be analyzed by a radiologist, and the results will be sent to your referring physician, typically within a few days.

Interpreting CT Scan Results: Understanding the Findings

After your CT scan, a radiologist will carefully analyze the images and prepare a detailed report. This process involves examining the cross-sectional views and any 3D reconstructions to identify normal and abnormal structures.

Key Aspects of CT Scan Interpretation:

• Identification of anatomical structures
• Detection of abnormalities or lesions
• Measurement of organ sizes and tissue densities
• Assessment of vascular structures and blood flow
• Comparison with previous imaging studies (if available)

How long does it take to get CT scan results? While the scan itself is quick, the interpretation process can take anywhere from a few hours to several days, depending on the complexity of the case and the urgency of the situation. Your doctor will discuss the findings with you once the report is available.

What if the CT scan shows an abnormality? If the scan reveals any concerning findings, your doctor will explain the results and discuss potential next steps. This may include additional tests, follow-up imaging, or referral to a specialist for further evaluation and treatment planning.

CT Scans vs. Other Imaging Modalities: Comparing Diagnostic Tools

While CT scans are incredibly versatile, they are just one of several imaging techniques available to medical professionals. Understanding how CT compares to other modalities can help patients appreciate its unique strengths and limitations.

CT Scans Compared to Other Imaging Methods:

• X-rays: CT provides more detailed 3D information compared to traditional 2D X-rays
• MRI: CT is faster and better for imaging bone, while MRI excels at soft tissue contrast
• Ultrasound: CT offers greater depth and is not limited by air or bone interference
• PET: CT provides anatomical detail, while PET shows metabolic activity (often combined in PET-CT)

When is a CT scan preferred over other imaging techniques? CT scans are often the modality of choice for:

1. Emergency trauma assessment
2. Detailed bone and joint imaging
3. Lung and chest evaluations
4. Quick, whole-body screening
5. Guiding interventional procedures

However, the optimal imaging method depends on the specific clinical question and patient factors.

Radiation Exposure in CT Scans: Balancing Benefits and Risks

CT scans utilize ionizing radiation to generate images, which has led to concerns about potential long-term health effects. While the benefits of CT scans in diagnosing and managing medical conditions often outweigh the risks, it’s important to understand and minimize radiation exposure.

Strategies for Reducing Radiation Exposure:

• Justification: Ensuring CT scans are medically necessary
• Optimization: Using the lowest radiation dose needed for diagnostic quality
• Dose modulation: Adjusting radiation levels based on body region and patient size
• Shielding: Protecting radiosensitive organs when possible
• Alternative imaging: Considering non-radiation options when appropriate

How much radiation does a typical CT scan deliver? The radiation dose from a CT scan varies depending on the type of exam and the body part being imaged. A chest CT scan, for example, delivers approximately 7 millisieverts (mSv) of radiation, which is equivalent to about 2 years of natural background radiation exposure.

Are there long-term risks associated with CT scan radiation? While the risk of developing cancer from a single CT scan is very low, cumulative exposure over time may increase this risk slightly. Healthcare providers carefully weigh the immediate diagnostic benefits against potential long-term risks when recommending CT scans.

Advances in CT Technology: Innovations Shaping the Future of Medical Imaging

The field of CT imaging continues to evolve rapidly, with new technologies enhancing image quality, reducing radiation dose, and expanding clinical applications. These advancements are revolutionizing diagnostic capabilities and improving patient care.

Recent Innovations in CT Technology:

1. Dual-energy CT: Provides material decomposition and improved tissue characterization
2. Photon-counting detectors: Offers higher resolution and reduced radiation dose
3. Artificial intelligence integration: Enhances image reconstruction and analysis
4. Ultra-fast scanning: Enables cardiac imaging with minimal motion artifacts
5. Spectral imaging: Allows for better differentiation of tissues and materials

How are these advancements improving patient care? These technological innovations are leading to:

• More accurate diagnoses
• Reduced need for invasive procedures
• Lower radiation exposure
• Expanded applications in complex cases
• Faster scan times and improved patient comfort

As CT technology continues to progress, we can expect even more precise and personalized diagnostic capabilities in the future.

CT scans have revolutionized medical imaging, providing invaluable insights into the human body’s internal structures. By offering detailed, cross-sectional views of organs, bones, and soft tissues, CT scans enable healthcare professionals to diagnose a wide range of conditions with remarkable accuracy. From detecting tumors and assessing internal injuries to guiding complex surgical procedures, the applications of CT technology are vast and continually expanding.

As we’ve explored in this comprehensive guide, CT scans involve a careful balance of benefits and considerations. The use of contrast agents can enhance diagnostic capabilities, but requires thoughtful patient preparation and monitoring. Radiation exposure, while generally low, is an important factor to consider, particularly for patients requiring multiple scans over time. However, ongoing technological advancements are steadily improving image quality while reducing radiation doses, making CT scans safer and more effective than ever before.

For patients undergoing CT scans, understanding the procedure, proper preparation, and what to expect can help alleviate anxiety and ensure optimal results. By working closely with healthcare providers and following recommended guidelines, individuals can maximize the benefits of this powerful diagnostic tool while minimizing potential risks.

As medical imaging continues to evolve, CT scans will undoubtedly play a crucial role in shaping the future of healthcare. From early disease detection to personalized treatment planning, the impact of CT technology on patient outcomes and quality of care cannot be overstated. By staying informed about the latest developments in CT imaging, both healthcare professionals and patients can make the most of this remarkable diagnostic resource.

Computed Tomography (CT) Scan | Johns Hopkins Medicine

What You Need to Know

• A CT scan is a diagnostic imaging exam that uses X-ray technology to produce images of the inside of the body.
• A CT scan can show detailed images of any part of the body, including the bones, muscles, organs and blood vessels.
• CT scans can also be used for fluid or tissue biopsies, or as part of preparation for surgery or treatment.
• CT scans are frequently done with and without contrast agent to improve the radiologist’s ability to find any abnormalities.

What is a CT scan?

Computed tomography is commonly referred to as a CT scan. A CT scan is a diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce images of the inside of the body. It shows detailed images of any part of the body, including the bones, muscles, fat, organs and blood vessels.

CT scans are more detailed than standard X-rays. In standard X-rays, a beam of energy is aimed at the body part being studied. A plate behind the body part captures the variations of the energy beam after it passes through skin, bone, muscle and other tissue. While much information can be obtained from a regular X-ray, a lot of detail about internal organs and other structures is not available.

In CT, the X-ray beam moves in a circle around the body. This allows many different views of the same organ or structure and provides much greater detail. The X-ray information is sent to a computer that interprets the X-ray data and displays it in two-dimensional form on a monitor. Newer technology and computer software makes three-dimensional images possible.

CT scans may be performed to help diagnose tumors, investigate internal bleeding, or check for other internal injuries or damage. CT can also be used for a tissue or fluid biopsy.

Why are CT scans sometimes ordered with contrast?

CT scans may be done with or without contrast. Contrast refers to a substance taken by mouth or injected into an IV line that causes the particular organ or tissue under study to be seen more clearly. Contrast examinations may require you to fast for a certain period of time before the procedure. Your doctor will notify you of this prior to the procedure.

You will need to let your doctor know if you have ever had a reaction to any contrast media and/or any kidney problems. A reported seafood allergy is not considered to be a contraindication for iodinated contrast. If you have any medical conditions or recent illnesses, inform your doctor.

How do I prepare for a CT scan?

If you are having a computed tomography angiography (CTA) or a virtual colonoscopy, you will be given specific instructions when you make your appointment.

PRECAUTIONS: If you are pregnant or think you may be pregnant, please check with your doctor before scheduling the exam.

CLOTHING: You may be asked to change into a patient gown. If so, a gown will be provided for you. Please remove all piercings and leave all jewelry and valuables at home.

CONTRAST MEDIA: Contrast may be indicated for your exam. The contrast media improves the radiologist’s ability to find structures that are abnormal and understand normal anatomy better.

• Some patients should not have an iodine-based contrast media. If you have problems with your kidney function, please inform your radiologist in advance. We may be able to perform the scan without the contrast media or find an alternate imaging exam.
• The most common type of CT scan with contrast is the double-contrast study, which will require you to drink a contrast media before your exam begins in addition to the IV contrast. The more contrast you are able to drink, the better the images are for the radiologist to visualize your digestive tract.

ALLERGY: Please inform the access center representative when you schedule your scan if you have had an allergic reaction to any contrast media. IV contrast will not be administered if you have had a severe or anaphylactic reaction to any contrast media in the past. Mild to moderate reactions warrant a plan that includes taking medication prior to the CT examination. These plans will be discussed with you in detail when you schedule your exam. Any known reactions to a contrast media should be discussed with your personal physician.

EAT/DRINK: If your study was ordered without contrast, you can eat, drink and take your prescribed medications prior to your exam.

If your doctor orders a CT scan with contrast, do not eat anything three hours prior to your CT scan. We encourage you to drink clear liquids. You may also take your prescribed medications prior to your exam.

DIABETICS: People with diabetes should eat a light breakfast or lunch three hours prior to the scan time. Depending on your oral medication for diabetes, you may be asked to discontinue use of the medication for 48 hours after the CT examination. Detailed instructions will be given following your examination.

MEDICATION: All patients can take their prescribed medications as usual.

The Newest CT: Faster Than a Heartbeat

A new CT scanner will change the management and outcomes of coronary artery disease. The CT scan captures images of the heart between beats, leading to clearer images to help detect anatomic and functional characteristics of coronary artery disease. This technology can also be used to help replace invasive tests to determine which patients with chest pain need intervention.

Read more

What are the risks of a CT scan?

If you are pregnant or think you may be pregnant, you should notify your health care provider.

The amount of radiation dose used in a CT scan is small. You may want to ask your doctor about the amount of radiation used during the CT procedure and the risks related to your particular situation.

If you are claustrophobic or tend to become anxious easily, tell your doctor ahead of time. You may be prescribed a mild sedative to take before the procedure to make you more comfortable.

What happens during a CT scan?

CT scans may be performed on an outpatient basis or as part of your stay in a hospital. Procedures may vary depending on your condition and your physician’s practices. Generally, CT scans follow this process:

• You may be asked to change into a patient gown. If so, a gown will be provided for you. A locker will be provided to secure all personal belongings. Please remove all piercings and leave all jewelry and valuables at home.
• If you are to have a procedure done with contrast, an IV line will be started in the hand or arm for injection of the contrast media. For oral contrast, you will be given a liquid contrast preparation to swallow. In some situations, the contrast may be given rectally.
• You will lie on a scan table that slides into a large, circular opening of the scanning machine.
• The technologist will be in another room where the scanner controls are located. However, you will be in constant sight of the technologist through a window. Speakers inside the scanner will enable the technologist to communicate with and hear you. You may have a call button so that you can let the technologist know if you have any problems during the procedure. The technologist will be watching you at all times and will be in constant communication.
• As the scanner begins to rotate around you, X-rays will pass through the body for short amounts of time. You will hear clicking sounds, which are normal.
• The X-rays absorbed by the body’s tissues will be detected by the scanner and transmitted to the computer. The computer will transform the information into an image to be interpreted by the radiologist.
• It is important that you remain very still during the procedure. You may be asked to hold your breath at various times during the procedure.
• If contrast media is used for your procedure, you may feel some effects when the contrast is injected into the IV line. These effects include a flushing sensation, a salty or metallic taste in the mouth, a brief headache, or nausea and/or vomiting. These effects usually last for a few moments.
• You should notify the technologist if you have any breathing difficulties, sweating, numbness or heart palpitations.
• When the procedure has been completed, you will be removed from the scanner.
• If an IV line was inserted for contrast administration, the line will be removed.
• While the CT procedure itself causes no pain, having to lie still for the length of the procedure might cause some discomfort or pain, particularly in the case of a recent injury or invasive procedure, such as surgery. The technologist will use all possible comfort measures and complete the procedure as quickly as possible to minimize any discomfort or pain.

What happens after a CT scan?

• If contrast media was used during your procedure, you may be monitored for a period of time for any side effects or reactions to the contrast, such as itching, swelling, rash or difficulty breathing.
• If you notice any pain, redness and/or swelling at the IV site after you return home following your procedure, you should notify your doctor, as this could indicate an infection or other type of reaction.
• There is typically no special type of care required after a CT scan. You may resume your usual diet and activities unless your doctor advises you differently.
• Your doctor may give you additional or alternate instructions after the procedure, depending on your particular situation.

What are some of the advances in CT technology?

Advances in CT technology include:

• High-resolution CT: This type of CT scan uses very thin slices (less than 0. 1 inches), which are effective in providing greater detail in certain conditions, such as lung disease.
• Helical or spiral CT: During this type of CT scan, both the patient and the X-ray beam move continuously, with the X-ray beam circling the patient. The images are obtained much more quickly than with standard CT scans. The resulting images have greater resolution and contrast, providing more detailed information. Multidetector-row helical CT scanners may be used to obtain information about calcium buildup inside the coronary arteries of the heart.
• Ultrafast CT (also called electron beam CT): This type of CT scan produces images very rapidly, thus creating a type of “movie” of moving parts of the body, such as the chambers and valves of the heart. This scan may also be used to obtain information about calcium buildup inside the coronary arteries of the heart, but the helical scanners are much more common.
• Computed tomographic angiography (CTA): Angiography (or arteriography) is an X-ray image of the blood vessels. A CT angiogram uses CT technology rather than standard X-rays or fluoroscopy to obtain images of blood vessels — for example, the coronary arteries of the heart.
• Combined positron emission tomography and CT (PET/CT): The combination of CT and positron emission tomography technologies into a single machine is referred to as PET/CT. PET/CT combines the ability of CT to provide detailed anatomy with that of PET to show cell function and metabolism in order to offer greater accuracy in the diagnosis and treatment of certain types of diseases, particularly cancer. PET/CT may also be used to evaluate conditions such as epilepsy, Alzheimer’s disease and coronary artery disease.

CT scan: MedlinePlus Medical Encyclopedia

A computed tomography (CT) scan is an imaging method that uses x-rays to create pictures of cross-sections of the body.

Related tests include:

• Abdominal and pelvis CT scan
• Cranial or head CT scan
• Cervical, thoracic, and lumbosacral spine CT scan
• Orbit CT scan
• Chest CT scan
• CT angiogram

You will be asked to lie on a narrow table that slides into the center of the CT scanner.

Once you are inside the scanner, the machine’s x-ray beam rotates around you. Modern spiral scanners can perform the exam without stopping. There is very little noise.

A computer creates separate images of the body area, called slices. These images can be stored, viewed on a monitor, or copied to a disk. Three-dimensional models of the body area can be created by stacking the slices together.

You must stay still during the exam, because movement causes blurred images. You may be told to hold your breath for short periods of time.

Complete scans most often take only a few minutes. The newest scanners can image your entire body in less than 30 seconds.

Certain exams require a special dye, called contrast, to be delivered into your body before the test starts. Contrast helps certain areas show up better on the x-rays.

Let your health care provider know if you have ever had a reaction to contrast. You may need to take medicines before the test in order to avoid another reaction.

Contrast can be given several ways, depending on the type of CT being performed.

• It may be delivered through a vein (IV) in your hand or forearm.
• You might drink the contrast before your scan. When you drink the contrast depends on the type of exam being done. The contrast liquid may taste chalky, although some are flavored. The contrast passes out of your body through your stools.
• Rarely, the contrast may be given into your rectum using an enema.

If contrast is used, you may also be asked not to eat or drink anything for 4 to 6 hours before the test.

Before receiving IV contrast, tell your provider if you take the diabetes medicine metformin (Glucophage). People taking this medicine may need to stop temporarily. Also let your provider know if you have any problems with your kidneys. The IV contrast can worsen kidney function.

Find out if the CT machine has a weight limit if you weigh more than 300 pounds (135 kilograms). Too much weight can damage the scanner.

You will need to remove jewelry and wear a gown during the study.

Some people may have discomfort from lying on the hard table.

Contrast given through an IV may cause a slight burning feeling, a metallic taste in the mouth, and a warm flushing of the body. These sensations are normal and usually go away within a few seconds.

A CT scan creates detailed pictures of the body, including the brain, chest, spine, and abdomen. The test may be used to:

• Diagnose an infection
• Guide a doctor to the right area during a biopsy
• Identify masses and tumors, including cancer
• Study blood vessels

Results are considered normal if the organs and structures being examined are normal in appearance.

Abnormal results depend on the part of the body being studied. Talk to your provider about questions and concerns.

Risks of having CT scans include:

• Allergic reaction to the contrast dye
• Damage to kidney function from the contrast dye
• Exposure to radiation

CT scans expose you to more radiation than regular x-rays. Having many x-rays or CT scans over time may increase your risk for cancer. However, the risk from any one scan is small. You and your provider should weigh this risk against the value of the information that will come from a CT scan. Most new CT scan machines have the ability to reduce the radiation dose.

Some people have allergies to contrast dye. Let your provider know if you have ever had an allergic reaction to injected contrast dye.

• The most common type of contrast given into a vein contains iodine. If you have an iodine allergy, contrast may cause nausea or vomiting, sneezing, itching, or hives.
• If you absolutely must be given such contrast, your provider may give you antihistamines (such as Benadryl) or steroids before the test.
• Your kidneys help remove iodine from the body. You may need to receive extra fluids after the test to help flush iodine out of your body if you have diabetes or kidney disease.

Rarely, the dye may cause a life-threatening allergic response called anaphylaxis. If you have any trouble breathing during the test, tell the scanner operator immediately. Scanners come with an intercom and speakers, so the operator can hear you at all times.

CAT scan; Computed axial tomography scan; Computed tomography scan

• CT scan

Blankensteijn JD, Lely RJ. Computed tomography. In: Sidawy AN, Perler BA, eds. Rutherford’s Vascular Surgery and Endovascular Therapy. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 29.

Levine MS, Gore RM. Diagnostic imaging procedures in gastroenterology. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 124.

Van Thielen T, van den Hauwe L, Van Goethem JW, Parizel PM.Current status of imaging of the spine and anatomical features. In: Adam A, Dixon AK, Gillard JH, Schaefer-Prokop CM, eds. Grainger & Allison’s Diagnostic Radiology: A Textbook of Medical Imaging. 7th ed. Philadelphia, PA: Elsevier; 2021:chap 47.

Updated by: Jason Levy, MD, FSIR, Northside Radiology Associates, Atlanta, GA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

8.10. Measurement of mean value and standard deviation of intensity in space

____________________________________________________________________________________________

The functionality is available in an add-on module that is activated in the edition
“Pro” for a fee
______________________________________________________________________________________________

The VOI Sphere tool is similar to the ROI tools described in section 2.17, but
measurements are performed in a space bounded by a sphere.

8.10.1 Building a sphere

____________________________________________________________________________________________

The functionality is available in an add-on module that is activated in the edition
“Pro” for a fee
______________________________________________________________________________________________

To draw a sphere, do the following:

1. Select the series to be measured, navigate to the image where you want to
   be the center of the sphere.

2. Activate the VOI sphere tool by clicking the button on the toolbar
   left, right or middle mouse button. For further work
   with the tool, use the button with which the tool was activated.
   See Section 1.14 for more information on tool management.

3. The VOI sphere can be built in two ways:

   • Move the cursor to the point where the center of the sphere should be.
     Click the mouse button. Set the desired sphere diameter by moving
     mouse. To complete the construction, click the mouse button;

   • click the mouse button at the point where the center should be
     sphere, and holding down the mouse button, set the desired diameter
     spheres. To fix the diameter of the sphere, release the mouse button.

4. To cancel an incomplete build, press the Esc button on your keyboard.

The following parameters are displayed next to the sphere:

• minimum intensity value;

• maximum intensity value;

• average intensity value;

• standard deviation;

In the CT and PET windows, only the results for the corresponding series are displayed, in the window
CT+PET — for both series.

8.10.2 Location of the sphere in space

____________________________________________________________________________________________

The functionality is available in an add-on module that is activated in the edition
“Pro” for a fee
______________________________________________________________________________________________

The MIP window always displays all constructed spheres. In other windows
the image shows the line of intersection of the sphere with the image plane and the results
measurements. As you move away from the center of the sphere, the diameter of this circle decreases. If
sphere does not intersect with the image plane, then the measurement results for the sphere do not
displayed in this window.

If the center of the sphere is in the current image and the Sphere tool is activated
VOI” , then crosshairs are displayed in the center of the sphere and on its border.

8.10.3 Actions with the sphere

____________________________________________________________________________________________

The functionality is available in an add-on module that is activated in the edition
“Pro” for a fee
______________________________________________________________________________________________

To edit a sphere, do the following:

1. Navigate to the image that contains the center of the sphere. For this
   scroll through the slices until crosshairs appear in the center and on the border of the sphere.

2. To move the sphere, move the cursor over the crosshairs at its center, and while holding
   pressed left mouse button or the button that is currently activated
   tool, move the mouse. When hovering the cursor, the crosshair increases.

3. To change the radius, move the cursor over the crosshairs on the boundary, and while holding
   pressed left mouse button or the button that is currently activated
   tool, move the mouse. When hovering the cursor, the crosshair increases.

To move a block with measurement results, place the cursor on it and move
mouse while holding down the left mouse button or the button that is currently
tool is activated. For this, it is not necessary that the center of the sphere be on the current
image.

To remove a sphere, right-click on the corresponding block with
measurement results or on the crosshairs in the center or on the borders of the sphere and select
“Delete Object” command.

8.10.4 Rendering parameters

____________________________________________________________________________________________

The functionality is available in an add-on module that is activated in the edition
“Pro” for a fee
______________________________________________________________________________________________

To change the drawing parameters of the constructed sphere:

1. Place the cursor on the block with measurement results or on the crosshairs in the center or
   at the edge of the sphere.

2. Right-click.

3. In the context menu that opens, select “Set
   display. ..”.

4. In the dialog box that opens, set the color by clicking the left mouse button on
   colored square.

5. Set the object name, line thickness and font size.

6. To connect the block with the measurement results to the sphere with a dotted line,
   set the “Footnote” flag.

7. To use the entered values ​​by default, set the flag
   “Set as default”.

8. To apply the settings, click “OK”, to cancel the changes, click
   “Cancel”.

CT of the temporal bone

CT of the temporal bones is a non-invasive method for diagnosing the temporal bone, adjacent soft tissues and anatomical structures located in this area. The examination is carried out using x-rays, the results are displayed on the monitor screen in the form of layered images in three planes. Computed tomography allows you to determine the state of the smallest structures of the auditory canal, middle ear and make an accurate diagnosis. As a rule, it is prescribed in cases where other research methods have proved to be insufficiently informative.

Clinical Diagnostic Center specializes in diagnostic procedures. You can do a CT scan of the temporal bones at an affordable price in Nizhny Novgorod. The staff of our institution has the necessary qualifications to conduct such examinations. We invite you to sign up for a consultation and undergo computed tomography at any time convenient for you.

Purpose of CT of the temporal bones

Diagnosis of the state of the temporal bones is of decisive importance for identifying various pathologies and making a variety of diagnoses. In this section of the cranium, blood vessels and nerve fibers are concentrated, on which the normal functioning of the masticatory, vestibular, and auditory apparatus depends. Conventional radiography or ultrasound very often does not give an idea of ​​the pathological changes in this area, but computed tomography of the temporal bones allows you to get a more detailed and clear picture.

This is the most informative and effective way to diagnose diseases at an early stage. Black-and-white images of organs and tissues displayed on the monitor screen can be enlarged, zoomed in, and any area can be accurately examined. The slice thickness is about 1 mm. These are optimal values ​​for examining the following structures:

• pyramids of the temporal bone
• cochlea, vestibule, anterior and posterior semicircular canal
• mastoid cells and antrum
• ossicles of the middle ear
• ear canal walls
• jugular fossa

The 3D image obtained during the examination gives the most clear idea of ​​the anatomical structure of the patient’s organs. This is especially important when preparing for surgery for an inner ear implant.

Indications for CT of the temporal bones

CT of the temporal bones makes it possible to diagnose inflammatory, traumatic, tumor pathologies. Changes and diseases detected during the examination include:

• hematomas
• vascular pathologies
• arachnoiditis, encephalitis, abscess, pus between meninges
• damage to bones and soft tissues in the region of the temporal bone
• traumatic injuries (cracks, fractures)
• developmental anomalies of bones and inner ear
• neoplasms located in the region of the temporal bones

CT scans of the temporal bones are usually prescribed by neurologists, ENT doctors, and neurosurgeons. The basis for the examination is the pathological changes identified during other types of diagnostics.

Indications for CT scan of the temporal bones:

• trauma of the skull with suspected fracture and bruising of soft tissues in the region of the temporal bone
• inflammatory diseases of the ear (purulent otitis media, ethmoiditis, involvement of the meninges in the inflammatory process)
• vestibular disorders (dizziness, unsteadiness when walking)
• progressive hearing loss, ringing or tinnitus
• changes in the functioning of the facial nerve with the development of weakness of mimic muscles
• identified tumor processes

The doctor also prescribes a CT scan to examine the temporal bones in preparation for the operation to implant the electrode.

How a CT scan of the temporal bones works

The CT scanner is a large camera with a retractable bed. During the examination, the patient lies on the table of the tomograph. To avoid involuntary movements that can distort the scan results, during the examination, the head is fixed with a special pillow and straps.

During the scan, the table moves into the tomograph tunnel, while the patient’s head must be at the level of the radiation source. The waves reproduced by the device pass through the soft organic structures of the body and are displayed on the monitor in the form of images. The medical staff at this time is in the next room and monitors the progress of the procedure. The patient does not experience discomfort or pain.

CT of the temporal bones with contrast consists of several stages: first, a native scan is performed, then an iodine-containing preparation is injected. The final stage is rescanning to obtain contrast images. After taking images of the area under study, the doctor checks their clarity and detail.

CT scan results of the temporal bone

Deciphering the results of computed tomography of the temporal bones takes from 30 minutes to 1.5 hours. The radiologist describes the images obtained during the examination. When pathological changes are detected, a conclusion is made regarding their nature, causes and degree of localization.

The patient receives images on digital media or film, as well as a conclusion certified by the doctor’s signature. It should be understood that this conclusion is not a diagnosis. Making an accurate diagnosis and prescribing treatment is the responsibility of the attending physician.

Preparation for CT scan of the temporal bone

No special preparation is required for the appointment of tomography without contrast. If a CT scan with the introduction of a contrast agent is prescribed, it is necessary to refrain from eating for at least 6 hours and drink only clean water. Metal jewelry, hearing aid, dentures (removable) should be removed before the procedure.