CT Scan

A CT of the brain is a noninvasive diagnostic imaging procedure that uses special X-rays measurements to produce horizontal, or axial, images (often called slices) of the brain. Brain CT scans can provide more detailed information about brain tissue and brain structures than standard X-rays of the head, thus providing more data related to injuries and/or diseases of the brain.

During a brain CT, the X-ray beam moves in a circle around the body, allowing many different views of the brain. The X-ray information is sent to a computer that interprets the X-ray data and displays it in a two-dimensional (2D) form on a monitor.

Brain CT scans may be done with or without “contrast.” Contrast refers to a substance taken by mouth or injected into an intravenous (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 physician will notify you of this prior to the procedure.

Other related procedures that may be used to diagnose brain disorders include X-rays , magnetic resonance imaging (MRI) of the brain , positron emission tomography (PET) scan of the brain , and cerebral arteriogram.

What are the reasons for a CT scan of the brain?

A CT of the brain may be performed to assess the brain for tumors and other lesions, injuries, intracranial bleeding, structural anomalies (e.g., hydrocephalus, infections, brain function or other conditions), particularly when another type of examination (e.g., X-rays or a physical exam) are inconclusive.

A brain CT may also be used to evaluate the effects of treatment on brain tumors and to detect clots in the brain that may be responsible for strokes. Another use of brain CT is to provide guidance for brain surgery or biopsies of brain tissue.

There may be other reasons for your doctor to recommend a CT of the brain.

What are the risks of a CT scan of the brain?

You may want to ask your doctor about the amount of radiation used during the brain CT procedure and the risks related to your particular situation. You should keep a record of your past history of radiation exposure, such as previous CT scans and other types of X-rays, so that you can inform your doctor. Risks associated with radiation exposure may be related to the cumulative number of X-ray examinations and/or treatments over a long period of time.

To safeguard your health, consider the following precautions before scheduling a brain CT:

Pregnancy: If you are pregnant or suspect that you may be pregnant, you should notify your doctor. Radiation exposure during pregnancy may lead to birth defects. If it is necessary for you to have a CT of the brain, special precautions will be made to minimize the radiation exposure to the fetus. 

Contrast media: If contrast media is used during a brain CT, the patient may develop an an allergic reaction to the media. Some patients should not have an iodine-based contrast media. Patients who are allergic to or sensitive to medications should notify their doctor. When you schedule your brain CT scan, you should inform the access center representative if you have had an allergic reaction to any contrast media or if you have kidney failure or other kidney problems. IV contrast will not be administered if you have had a severe or anaphylactic reaction to any contrast media in the past. You may be able to have the scan performed without contrast media or have an alternative imaging exam. . A reported seafood allergy is not considered to be a contraindication for iodinated contrast. Nursing mothers may want to wait 24 hours after contrast material is injected before resuming breastfeeding.

Diabetes: Patients taking the diabetes medication metformin (Glucophage) should alert their doctors before having an IV contrast injection as it may cause a rare condition called metabolic acidosis. If you take metformin, you will be asked to stop taking it at the time of the procedure and wait 48 hours after your procedure before restarting this medication. A blood test to check kidney function may be required before you can resume taking metformin.

There may be other risks depending on your specific medical condition. Be sure to discuss any concerns with your doctor prior to the procedure.

How do I prepare for a CT scan of the brain?

If you are having computed tomography angiography (CTA) , you will be given specific instructions when you make your appointment. The following instructions will help you prepare for your brain CT:

• 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:You will be asked to sign a consent form that will detail the risks and side-effects associated with contrast media injected through a small tube places in a vein called an intravenous (IV) line. The most common type of brain CT scan with contrast is the double-contrast study that will require you to drink a contrast media before your exam begins in addition to the IV contrast. If you had mild to moderate reactions in the past, you will likely need to take medication prior to the brain CT scan.
• Food and drink:If your doctor ordered a brain CT scan without contrast, you can eat, drink and take your prescribed medications prior to your exam. If your doctor ordered a CT of the brain with contrast, do not eat anything three hours prior to your brain CT. You are encouraged to drink clear liquids.
• Diabetics:Diabetics should eat a light breakfast or lunch three hours prior to the scheduled scan. Depending on your oral medication for diabetes, you may be asked to discontinue the use of your medication for 48 hours afterthe brain CT scan. If you have a CT scan with Johns Hopkins radiology, detailed instructions will be given following your examination.
• Medication: All patients can take their prescribed medications as usual, unless otherwise directed.

Based on your medical condition, your doctor may request other specific steps for brain CT preparation.

What happens during a CT scan of the brain?

Brain CT scans may be performed on an outpatient basis or as part of your hospital stay. Procedures may vary depending on your condition and your physician’s practices.

Generally, a brain CT scan involves the following steps:

• If you having a procedure done with contrast, an IV line will be started in the hand or arm for the injection of the contrast media. For oral contrast, you will be given a liquid contrast preparation to swallow.
• You will lie on a scan table that slides into a large, circular opening of the scanning machine. Pillows and straps may be used to prevent movement during the procedure.
• 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 two-way communication between the technologist and the patient. 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.
• You must 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 media is injected into the IV line. These effects include a flushing sensation, a salty or metallic taste in your mouth, a brief headache or nausea and/or vomiting. These effects usually last for a few moments.
• You should notify the technologist if you experience 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 brain CT 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 (e.g. 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 of the brain?

If contrast media was used during your brain CT scan, you may be monitored for a period of time to check for any side effects or reactions to the contrast media. Notify your radiologist or if you experience 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.

Otherwise, there is no special type of care required after a CT of the brain. Most patients are permitted to resume their usual diet and activities. Your doctor may provide additional or alternate instructions after the procedure, depending on your particular situation.

A CT scan uses X-rays to view specific areas of your body. These scans use safe amounts of radiation to create detailed images, which can help your doctor to detect any problems. A heart, or cardiac, CT scan is used to view your heart and blood vessels.

During the test, a specialized dye is injected into your bloodstream. The dye is then viewed under a special camera in a hospital or testing facility.

A Cardiac CT Scan may also be called a coronary CT angiogram if it’s meant to view the arteries that bring blood to your heart. The test may be called a coronary calcium scan if it’s meant to determine whether there’s a build-up of calcium in your heart.

Why is a Cardiac CT Scan performed?

Your doctor may order a Cardiac CT Scan to look for certain conditions, including:

• Congenital heart disease, or birth defects in the heart
• Buildup of a hard substance known as lipid plaque that may be blocking your coronary arteries
• Defects or injury to the heart’s four primary valves
• Blood clots within the heart’s chambers
• Tumors in or on the heart

A Cardiac CT Scan is a common test for people experiencing heart problems. This is because it allows your doctor to explore the structure of the heart and the adjacent blood vessels without making any incisions.

What are the risks of a Cardiac CT Scan?

A Cardiac CT Scan carries very few risks.

Contrast Dye

Most of the contrast material, sometimes referred to as dye, used for CT scans contains iodine. This iodine is later flushed from the body by the kidneys.

If your kidneys have been affected by disease or infection, such as diabetes, you may need to drink extra fluids after the test to help your kidneys remove the dye. However, newer dyes carry much less risk to the kidneys.

Allergic or adverse reactions to iodine-based materials are categorized as mild, moderate, and severe. You should let your doctor know if you experience any of the following symptoms:

• Mild reactions to the contrast material include itching and skin flushing.
• Moderate reactions can include severe skin rash or hives.
• Severe reactions can include difficulty breathing and cardiac arrest.

You’re at greater risk of an allergic or adverse reaction to iodine-based material if you’ve had a previous reaction or if you’ve received a large amount of contrast material within the past 24 hours.

Other risk factors include dehydration, taking medications such as nonsteroidal anti-inflammatory drugs (NSAIDs), and certain health conditions, such as sickle cell anemia or thyroid disorder.

Talk with your doctor if you feel you’re at risk of a reaction. There may be medication available to help you avoid reactions.

Radiation

As with any X-ray, there’s some exposure to radiation. While typically harmless, this is an important issue for women who are pregnant or could be pregnant. The levels of radiation are considered safe for adults — there have been no documented side effects from low levels of radiation — but not for a developing foetus.

How do you prepare for a Cardiac CT Scan?

Your doctor will typically ask you to fast for four to eight hours before the scan. You’ll be able to drink water. However, avoid caffeinated drinks since caffeine can affect your heart rate.

You’ll be required to lie down on a table during the exam, so you may want to wear loose, comfortable clothing. You’ll also need to remove any jewellery and other metal items from your body, such as piercings.

Most people will be able to drive themselves home after the test. Unless you’ve been sedated, there’s no need to arrange for transportation.

How is a Cardiac CT Scan Performed?

A Cardiac CT Scan is performed in a hospital’s radiology department or a clinic that specializes in diagnostic procedures.

You may be given a beta-blocker before the scan. This medication slows down your heart so that clearer pictures can be taken. Small, sticky discs called electrodes are placed onto your chest to record the scan. The radiology technician inserts an intravenous line (IV) into a vein so that they can inject the radioactive dye into your arm. You may feel warm or flushed briefly or have a temporary metallic taste in your mouth when they inject the dye.

Before the start of the scan, you lie down on a bench, possibly in a specific position. The technician may use pillows or straps to ensure that you stay in the correct position for long enough to get a quality image. You may also have to hold your breath during brief individual scans, which last only 10 to 20 seconds.

To start the scan, the technician moves the table — via a remote from a separate room — into the CT machine. The CT machine looks like a giant doughnut made of plastic and metal. You’ll most likely go through the machine several times. Although you’re in the room by yourself, the technician can talk to you via an intercom.

After a round of scans, you may be required to wait for a few minutes while the technicians review the images to ensure they’re clear enough for your doctor to read. The whole test shouldn’t take longer than 10 minutes.

What happens after a Cardiac CT Scan?

After the procedure, you’ll be able to leave and go about your day. The dye will naturally work its way out of your body. Drinking more water will help speed up this process.

Getting the results from your Cardiac CT Scan doesn’t take long. Your doctor or the technician will go over the results with you.

Depending on what the images show, your doctor will advise you of any lifestyle changes, treatments, or procedures that need to be done. Common follow-up tests include a stress test and coronary catheterization.

For other cardiology related tests, click to visit Cardiology Department…

A computed tomography (CT or CAT) scan allows doctors to see inside your body. It uses a combination of X-rays and a computer to create pictures of your organs, bones, and other tissues. It shows more detail than a regular X-ray.

You can get a CT scan on any part of your body. The procedure doesn’t take very long, and it’s painless.

How Do CT Scans Work?

They use a narrow X-ray beam that circles around one part of your body. This provides a series of images from many different angles. A computer uses this information to create a cross-sectional picture. Like one piece in a loaf of bread, this two-dimensional (2D) scan shows a “slice” of the inside of your body.

How Are CT Scans Done?

You’d probably get a scan at a hospital or radiology clinic. Your doctor might tell you not to eat or drink for a few hours before the procedure. You may also need to wear a hospital gown and remove any metal objects, such as jewellery.

A radiology technologist will perform the CT scan. During the test, you’ll lie on a table inside a large, doughnut-shaped CT machine. As the table slowly moves through the scanner, the X-rays rotate around your body. It’s normal to hear a whirring or buzzing noise. Movement can blur the image, so you’ll be asked to stay very still. You may need to hold your breath at times.

How long the scan takes will depend on what parts of your body are being scanned. It can take anywhere from a few minutes to a half-hour. In most cases, you’ll go home the same day.

This process is repeated to produce a number of slices. The computer stacks these scans one on top of the other to create a detailed image of your organs, bones, or blood vessels. For example, a surgeon may use this type of scan to look at all sides of a tumor to prepare for an operation.

What Is It Used For?

Doctors order CT scans for a long list of reasons:

• CT scans can detect bone and joint problems, like complex bone fractures and tumors.
• If you have a condition like cancer, heart disease, emphysema, or liver masses, CT scans can spot it or help doctors see any changes.
• They show internal injuries and bleeding, such as those caused by a car accident.
• They can help locate a tumor, blood clot, excess fluid, or infection.
• Doctors use them to guide treatment plans and procedures, such as biopsies, surgeries, and radiation therapy.
• Doctors can compare CT scans to find out if certain treatments are working. For example, scans of a tumor over time can show whether it’s responding to chemotherapy or radiation

What Is a CT Scan with Contrast?

In a CT scan, dense substances like bones are easy to see. But soft tissues don’t show up as well. They may look faint in the image. To help them appear clearly, you may need a special dye called a contrast material. They block the X-rays and appear white on the scan, highlighting blood vessels, organs, or other structures.

Contrast materials are usually made of iodine or barium sulfate. You might receive these drugs in one or more of three ways:

• Injection: The drugs are injected directly into a vein. This is done to help your blood vessels, urinary tract, liver, or gallbladder stand out in the image.
• Orally: Drinking a liquid with the contrast material can enhance scans of your digestive tract, the pathway of food through your body.
• Enema: If your intestines are being scanned, the contrast material can be inserted in your rectum.

After the CT scan, you’ll need to drink plenty of fluids to help your kidneys remove the contrast material from your body.

Are There Any Risks?

CT scans use X-rays, which produce ionizing radiation. Research shows that this kind of radiation may damage your DNA and lead to cancer. But the risk is still very small — your chances of developing a fatal cancer because of a CT scan are about 1 in 2,000.

But radiation’s effect adds up over your lifetime. So your risk increases with every CT scan you get. Talk to your doctor about the procedure’s potential dangers and benefits, and ask why the CT scan is necessary.

Ionizing radiation may be more harmful in children. That’s because they’re still growing. They also have more years to get exposed to radiation. Before the procedure, you may want to ask the doctor or technician if the CT machine’s settings have been adjusted for a child.

Tell your physician if you’re pregnant. If you need imaging for your stomach area, your doctor may recommend an exam that doesn’t use radiation, such as an ultrasound.

What Are the Side Effects?

Some people are allergic to the contrast materials. Most of the time, the reaction is mild. It can lead to itchiness or a rash. In very few cases, the dye may trigger a life-threatening reaction. For this reason, your health care provider may want to monitor you for a short period after your CT scan. Tell your doctor about any allergies you have to medications, seafood, or iodine.

Your doctor should know, too, if you have diabetes and are taking the drug metformin. They’ll let you know if you should stop taking your medication before or after your procedure.

Although it’s rare, contrast materials can lead to kidney problems. Let your doctor know if you have any kidney issues before the CT scan.

Bone and Joint CT Scans are performed to demonstrate breaks (fractures), malignancy (cancer), degenerative disease and infection of the bones or joints in the body. They provide more detail of the bony architecture than X-Rays, but are less accurate than MRI scans in defining soft tissue damage

The process of taking a CT of a joint in the body begins by taking many different X-ray views at various different angles, which are then combined with the use of computer processing to create cross-sectional images of the bones and soft tissue inside of your body, including tissues inside of solid organ.

Various bone & joints in your body can be seen during a quality CT scan of the bone and joint including limb, shoulder, elbow, wrist, hip, knee, ankles, SI joints etc.

How the Test is Performed

Bone and Joint CT Scans are performed in the radiology department scanning room, with the patient lying flat (supine) on a CT table. The head is placed in a comfortable ‘docking pillow’ and the CT scanner gantry (donut) passess over and around the affected limb to perform the scan.

Reasons for a Joint CT scan:

CT scans are used for a multitude of reasons.

• They may be used to get a details of a fracture especially small bones.
• They may be use in diagnosis of degenerative disease of bones.
• They may be done to check for certain cancers in various different ways including to detect abnormal tumors, growths or lumps. They also identify the location of tumors, the stage of cancer, and where to perform a biopsy.They are important in planning for certain types of therapy and surgery, as well as in the aftermath to determine whether the patient’s body is responding to treatment.

Are There Any Risks?

• CT scans use X-rays, which produce ionizing radiation. Research shows that this kind of radiation may damage your DNA and lead to cancer. But the risk is still very small — your chances of developing a fatal cancer because of a CT scan are about 1 in 2,000.
• But radiation’s effect adds up over your lifetime. So your risk increases with every CT scan you get. Talk to your doctor about the procedure’s potential dangers and benefits, and ask why the CT scan is necessary.
• Ionizing radiation may be more harmful in children. That’s because they’re still growing. They also have more years to get exposed to radiation. Before the procedure, you may want to ask the doctor or technician if the CT machine’s settings have been adjusted for a child.
• Tell your physician if you’re pregnant. If you need imaging for your stomach area, your doctor may recommend an exam that doesn’t use radiation, such as an ultrasound.

What Are the Side Effects?

• Some people are allergic to the contrast materials. Most of the time, the reaction is mild. It can lead to itchiness or a rash. In very few cases, the dye may trigger a life-threatening reaction. For this reason, your health care provider may want to monitor you for a short period after your CT scan. Tell your doctor about any allergies you have to medications, seafood, or iodine.
• Your doctor should know, too, if you have diabetes and are taking the drug metformin. They’ll let you know if you should stop taking your medication before or after your procedure.
• Although it’s rare, contrast materials can lead to kidney problems. Let your doctor know if you have any kidney issues before the CT scan.

Computed tomography (CT) of the spine is a diagnostic imaging test used to help diagnose—or rule out—spinal column damage in injured patients. CT scanning is fast, painless, non-invasive 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 and discuss any recent illnesses, medical conditions, medications you’re taking, and allergies. You will be instructed not to eat or drink anything for a few hours beforehand if the exam requires contrast material. If you have a known allergy to contrast material, your doctor may prescribe medications to reduce the risk of an allergic reaction. These medications must be taken 12 hours prior to your exam. Leave jewelry at home and wear loose, comfortable clothing. You may be asked to wear a gown.

What is CT Scanning of the Spine?

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.

The cross-sectional images generated during a CT scan can be reformatted in multiple planes. They can even generate three-dimensional images. These images can be viewed on a computer monitor, printed on film or by a 3D printer, or transferred to a CD or DVD.

CT images of internal organs, bones, soft tissue and blood vessels provide greater detail than traditional x-rays, particularly of soft tissues and blood vessels.

Using CT, the bony structure of the spine vertebrae is clearly and accurately shown, as are intervertebral disks and, to some degree, the spinal cord soft tissues.

What are some common uses of the procedure?

Perhaps, the most frequent use of spinal CT is to detect—or to rule out—spinal column damage in patients who have been injured.

CT scanning of the spine is also performed to:

• Assess spine fractures due to injury.
• Evaluate the spine before and after surgery.
• Help diagnose spinal pain. One of the most common causes of spinal pain that may be diagnosed by ct is a herniated intervertebral disk. Occasionally, this diagnosis is made using CT Myelography.
• Accurately measure bone density in the spine and predict whether vertebral fractures are likely to occur in patients who are at risk of osteoporosis.
• Assess for congenital anomalies of the spine or scoliosis.
• Detect various types of tumors in the vertebral column, including those that have spread there from another area of the body. Some tumors that arise elsewhere are first identified by finding deposits of malignant cells (metastases) in the vertebrae; prostate cancer is an example.
• Guide diagnostic procedures such as the biopsy of a suspicious area to detect cancer, or the removal of fluid from a localized infection (abscess).

In patients with narrowing (stenosis) of the spine canal, vertebral fracture, infection or degenerative disease such as arthritis, CT of the spine may provide important information when performed alone or in addition to magnetic resonance imaging (MRI).

How should I prepare?

You should wear comfortable, loose-fitting clothing to your exam. You may need to wear a gown during 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. You may also be asked to remove hearing aids and removable dental work. Women will be asked to remove bras containing metal underwire. You may be asked to remove any piercings, if possible.

You will be asked not to eat or drink anything for a few hours beforehand, if contrast material will be used in your exam. You should inform your physician of 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 before the exact time of your exam.

Also, inform your doctor of any recent illnesses or other medical conditions and whether you have a history of heart disease, asthma, diabetes, and 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.

If your infant or young child is having a spinal CT, there are measures that can be taken to ensure that the test will not be a cause of anxiety for either the child or parent.

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.

In a conventional x-ray exam, a small amount of radiation is directed through the part of the body being examined. 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, so that the x-ray beam follows a spiral path. A special computer program processes this large volume of data to create two-dimensional cross-sectional images of your body. These images are then displayed on a monitor. CT imaging is sometimes compared to looking into a loaf of bread by cutting the loaf into thin slices. When the image slices are reassembled by computer software, the result is a very detailed multidimensional view of the body’s interior.

Refinements in detector technology allow nearly all CT scanners to obtain multiple slices in a single rotation. These scanners, called multi-slice or multidetector CT, allow thinner slices to be obtained in a shorter amount of time. This results in more detail and additional view capabilities.

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

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

For some CT exams, a contrast material is used to enhance visibility in the area of the body being studied.

How is the procedure performed?

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

Many scanners are fast enough that children can be scanned without sedation. In special cases, sedation may be needed for children who cannot hold still. Motion will cause blurring of the images and degrade the quality of the examination the same way that it affects photographs.

If a contrast material is used, it will be injected through an intravenous line (IV) into an arm vein during the procedure. A scan of the spine may also be done after injecting contrast material into the spinal canal (usually well below the bottom of the spinal cord) during a lumbar puncture test, also known as a myelogram. This will help to locate areas of inflammation or nerve compression or detect tumors.

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 as the actual CT scanning is performed. Depending on the type of CT scan, the machine may make several passes.

You may be asked 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, you will be asked to wait until the technologist verifies that the images are of high enough quality for accurate interpretation.

The entire exam is usually completed within 30 minutes.

What will I experience during and after the procedure?

CT exams are generally painless, fast and easy. With multidetector CT, the amount of time that the patient needs to lie still is reduced.

Though the scan is painless, you may have some discomfort from remaining still for several minutes or from the 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 an intravenous contrast material is used, you will feel a pinprick when the needle is inserted into your vein. You may feel warm or flushed while 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, this is a contrast effect and subsides quickly.

When you enter the CT scanner, you may see special light lines projected onto your body. These lines are used to ensure that you are properly positioned. 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 will be required to wear a lead apron to minimize radiation exposure.

After a CT exam, the technologist will remove the intravenous line used to inject the contrast material. The tiny hole made by the needle will be covered with a small dressing. You can return to your normal activities.

What are the benefits vs. risks?

Benefits

• Spinal CT scanning is a rapid procedure and offers an accurate evaluation of bone and most soft tissues. Using the latest equipment, the spine may be displayed in multiple planes and three-dimensional imaging may be reconstructed.
• 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 examinations 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.
• CT can be performed if you have an implanted medical device of any kind, unlike MRI.
• CT imaging provides real-time imaging, making it a good tool for guiding minimally invasive procedures such as needle biopsies and needle aspirations of many areas of the body, particularly the lungs, abdomen, pelvis and bones.
• A diagnosis determined by CT scanning may eliminate the need for exploratory surgery and surgical biopsy.
• No radiation remains in a patient’s body after a CT examination.
• X-rays used in CT scans 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.
• The effective 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.
• CT scanning is, in general, not recommended for pregnant women unless medically necessary because of potential risk to the unborn baby.
• 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.
• The risk of serious allergic reactions to contrast materials that contain iodine is extremely low, and radiology departments are well-equipped to deal with them. If you had prior allergic reactions to CT contrast materials, it is important to inform your doctor in advance. Medications may be prescribed prior to the CT scan to minimize the risk of allergic reactions.

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