How does the procedure work?

X-rays are a form of radiation like light or radio waves. X-rays pass through most objects, including the body. Once it is carefully aimed at the part of the body being examined, an x-ray machine produces a small burst of radiation that passes through the body, recording an image on photographic film or a special detector.

Different parts of the body absorb the x-rays in varying degrees. Dense bone absorbs much of the radiation while soft tissue, such as muscle, fat and organs, allow more of the x-rays to pass through them. As a result, bones appear white on the x-ray, soft tissue shows up in shades of gray and air appears black.

On a chest x-ray, the ribs and spine will absorb much of the radiation and appear white or light gray on the image. Lung tissue absorbs little radiation and will appear dark on the image.

Until recently, x-ray images were maintained on large film sheets (much like a large photographic negative). Today, most images are digital files that are stored electronically. These stored images are easily accessible and are frequently compared to current x-ray images for diagnosis and disease management.

How is the procedure performed?

Typically, two views of the chest are taken, one from the back and the other from the side of the body as the patient stands against the image recording plate. The technologist, an individual specially trained to perform radiology examinations, will position the patient with hands on hips and chest pressed against the image plate. For the second view, the patient's side is against the image plate with arms elevated.

Patients who cannot stand may be positioned lying down on a table for chest x-rays.

You must hold very still and may be asked to keep from breathing for a few seconds while the x-ray picture is taken to reduce the possibility of a blurred image. The technologist will walk behind a wall or into the next room to activate the x-ray machine.

When the examination is complete, you may be asked to wait until the radiologist determines that all the necessary images have been obtained.

The entire chest x-ray examination, from positioning to obtaining and verifying the images, is usually completed within 15 minutes.

Additional views may be required within hours, days or months to evaluate any changes in the chest.

What will I experience during and after the procedure?

A chest x-ray examination itself is a painless procedure.

You may experience discomfort from the cool temperature in the examination room and the coldness of the recording plate. Individuals with arthritis or injuries to the chest wall, shoulders or arms may have discomfort trying to stay still during the examination. The technologist will assist you in finding the most comfortable position possible that still ensures diagnostic image quality.

Who interprets the results and how do I get them?

A radiologist, a physician specifically trained to supervise and interpret radiology examinations, will analyze the images and send a signed report to your primary care or referring physician, who will discuss the results with you.

The results of a chest x-ray can be available almost immediately for review by your physician.

Follow-up examinations may be necessary. Your doctor will explain the exact reason why another exam is requested. Sometimes a follow-up exam is done because a potential abnormality needs further evaluation with additional views or a special imaging technique. A follow-up examination may also be necessary so that any change in a known abnormality can be monitored over time. Follow-up examinations are sometimes the best way to see if treatment is working or if a finding is stable or changed over time.

X-ray (Radiography) - Chest

Chest x-ray uses a very small dose of ionizing radiation to produce pictures of the inside of the chest. It is used to evaluate the lungs, heart and chest wall and may be used to help diagnose shortness of breath, persistent cough, fever, chest pain or injury. It also may be used to help diagnose and monitor treatment for a variety of lung conditions such as pneumonia, emphysema and cancer. Because chest x-ray is fast and easy, it is particularly useful in emergency diagnosis and treatment.

This exam requires little to no special preparation. Tell your doctor and the technologist if there is a possibility you are pregnant. Leave jewelry at home and wear loose, comfortable clothing. You may be asked to wear a gown.

What is a Chest X-ray (Chest Radiography)?

The chest x-ray is the most commonly performed diagnostic x-ray examination. A chest x-ray produces images of the heart, lungs, airways, blood vessels and the bones of the spine and chest.

An x-ray (radiograph) is a noninvasive medical test that helps physicians diagnose and treat medical conditions. Imaging with x-rays involves exposing a part of the body to a small dose of ionizing radiation to produce pictures of the inside of the body. X-rays are the oldest and most frequently used form of medical imaging.

What are some common uses of the procedure?

The chest x-ray is performed to evaluate the lungs, heart and chest wall.

A chest x-ray is typically the first imaging test used to help diagnose symptoms such as:

• breathing difficulties.
• a bad or persistent cough.
• chest pain or injury.
• fever.

Physicians use the examination to help diagnose or monitor treatment for conditions such as:

• pneumonia.
• heart failure and other heart problems.
• emphysema.
• lung cancer.
• positioning of medical devices.
• fluid or air collection around the lungs.
• other medical conditions.

  How should I prepare?

  A chest x-ray requires no special preparation.

  You will be asked to remove some of your clothes and to wear a gown during the exam. You may also be asked to remove jewelry, removable dental appliances, eye glasses and any metal objects or clothing that might interfere with the x-ray images.

  Women should always inform their physician and x-ray technologist if there is any possibility that they are pregnant. Many imaging tests are not performed during pregnancy so as not to expose the fetus to radiation. If an x-ray is necessary, precautions will be taken to minimize radiation exposure to the baby. See the Safety page for more information about pregnancy and x-rays.

• What does the equipment look like?

  The equipment typically used for chest x-rays consists of a wall-mounted, box-like apparatus containing the x-ray film, or a special plate that records the image digitally. An x-ray producing tube is positioned about six feet away.

  The equipment may also be arranged with the x-ray tube suspended over a table on which the patient lies. A drawer under the table holds the x-ray film or digital recording plate.

  A portable x-ray machine is a compact apparatus that can be taken to the patient in a hospital bed or the emergency room. The x-ray tube is connected to a flexible arm that is extended over the patient while an x-ray film holder or image recording plate is placed beneath the patient.

Computed Tomography (CT) - Chest

Computed tomography (CT) of the chest uses special x-ray equipment to examine abnormalities found in other imaging tests and to help diagnose the cause of unexplained cough, shortness of breath, chest pain, or fever. CT scanning is fast, painless, noninvasive and accurate. Because it is able to detect very small nodules in the lung, chest CT is especially effective for diagnosing lung cancer at its earliest, most curable stage.

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 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 Chest?
• What are some common uses of the procedure?
• How should I prepare?
• What does the equipment look like?
• How does the procedure work?

• How is the procedure performed?
• What will I experience during and after the procedure?
• Who interprets the results and how do I get them?
• What are the benefits vs. risks?
• What are the limitations of CT Scanning of the Chest?

What is CT Scanning of the Chest?

Computed tomography, more commonly known as a CT or CAT scan, is a diagnostic medical test that, like traditional x-rays, 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, and can even generate three-dimensional images. These images can be viewed on a computer monitor, printed on film 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 a variety of techniques, including adjusting the radiation dose based on patient size and new software technology, the amount of radiation needed to perform a chest CT scan can be significantly reduced. A low-dose chest CT produces images of sufficient image quality to detect many lung diseases and abnormalities using significantly less ionizing radiation than a conventional chest CT scan—in some cases lowering dose by 65 percent or more. Low dose chest CT is routinely used for evaluation of acquired and congenital lung abnormalities, such as pneumonia, interstitial lung disease or tumor evaluation. There is ongoing research to lower radiation doses even further. Your radiologist will decide the proper settings to be used for your scan depending on your medical problems and what information is needed from the CT scan. If your child is to have a CT scan, the proper low-dose pediatric settings should be used.

What are some common uses of the procedure?

Chest CT is used to:

• examine abnormalities found on conventional chest x-rays.
• help diagnose the causes of clinical signs or symptoms of disease of the chest, such as cough, shortness of breath, chest pain, or fever.
• detect and evaluate the extent of tumors that arise in the chest, or tumors that have spread there from other parts of the body.
• assess whether tumors are responding to treatment.
• help plan radiation therapy.
• evaluate injury to the chest, including the heart, blood vessels, lungs, ribs and spine.
• evaluate abnormalities of the chest found on fetal ultrasound examinations.

Chest CT can demonstrate various lung disorders, such as:

• benign and malignant tumors.
• pneumonia.
• tuberculosis.
• bronchiectasis, cystic fibrosis.
• inflammation or other diseases of the pleura (the covering of the lungs).
• interstitial and chronic lung disease.
• congenital abnormalities.

CT scanning has recently been approved for screening asymptomatic people who have smoked a significant amount of cigarettes by the Centers for Medicare and Medicaid Services. See the Lung Cancer Screening page for more information.

A CT angiogram (CTA) may be performed to evaluate the blood vessels (arteries and veins) in the chest. This involves the rapid injection of an iodine-containing fluid (contrast material) into a vein while obtaining CT images. See the CT Angiography (CTA) page for more information.

How should I prepare?

You should wear comfortable, loose-fitting clothing to your exam. You may be given a gown to wear during the procedure.

Metal objects, including jewelry, eyeglasses, dentures and hairpins, may affect the CT images and should be left at home or removed 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, or "dye," your doctor may prescribe medications (usually a steroid) to reduce the risk of an allergic reaction. These medications generally need to be taken 12 hours prior to administration of contrast material. 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, kidney disease or thyroid problems. Any of these conditions may increase the risk of an unusual adverse effect.

Women should always inform their physician and the CT technologist if there is any possibility that they may be pregnant. See the Safety page for more information about pregnancy and x-rays.

What does the equipment look like?

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

How does the procedure work?

In many ways CT scanning works very much like other x-ray examinations. Different body parts absorb the x-rays in varying degrees. It is this crucial difference in absorption that allows the body parts to be distinguished from one another on an x-ray film or CT electronic image.

In a conventional x-ray exam, a small amount of radiation is aimed at and passes through the part of the body being examined, recording an image on a special electronic image recording plate. Bones appear white on the x-ray; soft tissue, such as organs like the heart or liver, shows up in shades of gray, and air appears black.

With CT scanning, numerous x-ray beams and a set of electronic x-ray detectors rotate around you, measuring the amount of radiation being absorbed throughout your body. Sometimes, the examination 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, which 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 multislice CT or multidetector CT, allow thinner slices to be obtained in a shorter period of time, resulting in more detail and additional view capabilities.

Modern CT scanners are so fast that they 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 but especially children, the elderly and critically ill, all of whom may have difficulty in remaining 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.

To produce high-quality scans at a lower radiation dose, low-dose CT scanning uses a variety of techniques, including:

• dose modulation, in which radiation dosage is continuously adjusted to the patient's size at each location as the patient moves through the scanner
• "noise management" software to filter out unnecessary data
• the use of shields (this method depends on the type of CT scanner being used)
• external shields made out of bismuth may be placed on the patient
• the x-ray tube may be turned off during part of its rotation
• lower peak voltage settings

Your radiologist will select the appropriate dose reduction method(s) to accomplish the lowest possible dose necessary to answer the clinical question at hand.

How is the procedure performed?

The technologist begins by positioning you on the CT examination table, usually lying flat on your back. Straps and pillows may be used to help you maintain the correct position and to help you 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 into a vein shortly before scanning begins.

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, whether breathing or 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 examination is completed, you will be asked to wait until the technologist verifies that the images are of high enough quality for accurate interpretation.

The actual CT scanning takes less than 30 seconds and the entire process 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 scanning itself causes no pain, there may be some discomfort from having to remain still for several minutes and with placement of an IV. If you have a hard time staying still, are very nervous or anxious or have chronic pain, you may find a CT exam to be stressful. The technologist or nurse, under the direction of a physician, may offer you some medication to help you tolerate the CT scanning procedure.

For exams (excluding head and neck) your head will remain outside the hole in the center of the scanner. The scanner is approximately 24 inches wide, therefore, your entire body will be "inside" the scanner at one time such as with MRI.

If an intravenous contrast material is used, you will feel a pin prick when the needle is inserted into your vein. You will likely have a warm, flushed sensation during the injection of the contrast materials and a metallic taste in your mouth that lasts for at most a minute or two. You may experience a sensation like you have to urinate; however, this is actually a contrast effect and subsides quickly.

When you enter the CT scanner, special light lines may be seen projected onto your body, and are used to ensure that you are properly positioned. With modern CT scanners, you will hear only slight buzzing, clicking and whirring sounds 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 intravenous line used to inject the contrast material will be removed by the technologist, and the tiny hole made by the needle will be covered with a small dressing. You can return to your normal activities.

Who interprets the results and how do I get them?

A radiologist with expertise in supervising and interpreting radiology examinations will analyze the images and send an official report to your primary care physician or physician who referred you for the exam, who will discuss the results with you.

Follow-up examinations may be necessary. Your doctor will explain the exact reason why another exam is requested. Sometimes a follow-up exam is done because a potential abnormality needs further evaluation with additional views or a special imaging technique. A follow-up examination may also be necessary so that any change in a known abnormality can be monitored over time. Follow-up examinations are sometimes the best way to see if treatment is working or if a finding is stable or changed over time.

What are the benefits vs. risks?

Benefits

• CT is fast, which is important for patients who have trouble holding their breath.
• CT is widely available.
• 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.
• Low-dose CT scans of the chest use a lower dose of radiation than conventional chest CT.

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 Safety page for more information about radiation dose.
• Women should always inform their physician and x-ray or CT technologist if there is any possibility that they are pregnant. See the Safety 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 fetus in the womb.
• The risk of serious allergic reaction to contrast materials that contain iodine is extremely rare, and radiology departments are well-equipped to deal with them.
• In some patients with reduced kidney function, the dye used in CT scanning may worsen kidney function.

• 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.

What are the limitations of CT Scanning of the Chest?

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

Magnetic resonance imaging (MRI) may be better than CT for showing some types of soft-tissue abnormalities.

Even though the CT exam is very fast, motion from breathing or body movement during the exam may result in blurring of the images.

Computed Tomography (CT) - Head

Computed tomography (CT) of the head uses special x-ray equipment to help assess head injuries, severe headaches, dizziness, and other symptoms of aneurysm, bleeding, stroke and brain tumors. It also helps your doctor to evaluate your face, sinuses, and skull or to plan radiation therapy for brain cancer. 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 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 Head?
• What are some common uses of the procedure?
• How should I prepare?
• What does the equipment look like?
• How does the procedure work?

• How is the procedure performed?
• What will I experience during and after the procedure?
• Who interprets the results and how do I get them?
• What are the benefits vs. risks?
• What are the limitations of CT Scanning of the Head?

What is CT Scanning of the Head?

Computed tomography, more commonly known as a CT or CAT scan, is a diagnostic medical test that, like traditional x-rays, 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, and can even generate three-dimensional images. These images can be viewed on a computer monitor, printed on film 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.

CT scanning provides more detailed information on head injuries, stroke, brain tumors and other brain diseases than regular radiographs (x-rays).

What are some common uses of the procedure?

CT scanning of the head is typically used to detect:

• bleeding, brain injury and skull fractures in patients with head injuries.
• bleeding caused by a ruptured or leaking aneurysm in a patient with a sudden severe headache.
• a blood clot or bleeding within the brain shortly after a patient exhibits symptoms of a stroke.
• a stroke, especially with a new technique called Perfusion CT.
• brain tumors.
• enlarged brain cavities (ventricles) in patients with hydrocephalus.
• diseases or malformations of the skull.

CT scanning is also performed to:

• evaluate the extent of bone and soft tissue damage in patients with facial trauma, and planning surgical reconstruction.
• diagnose diseases of the temporal bone on the side of the skull, which may be causing hearing problems.
• determine whether inflammation or other changes are present in the paranasal sinuses.
• plan radiation therapy for cancer of the brain or other tissues.
• guide the passage of a needle used to obtain a tissue sample (biopsy) from the brain.
• assess aneurysms or arteriovenous malformations through a technique called CT angiography. For more information, see the CT Angiography page.

How should I prepare?

You should wear comfortable, loose-fitting clothing to your exam. You may be given a gown to wear during the procedure.

Metal objects, including jewelry, eyeglasses, dentures and hairpins, may affect the CT images and should be left at home or removed 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, or "dye," your doctor may prescribe medications (usually a steroid) to reduce the risk of an allergic reaction. These medications generally need to be taken 12 hours prior to administration of contrast material. 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, kidney disease or thyroid problems. Any of these conditions may increase the risk of an unusual adverse effect.

The radiologist also should know if you have asthma, multiple myeloma or any disorder of the heart, kidneys or thyroid gland, or if you have diabetes—particularly if you are taking Glucophage.

Women should always inform their physician and the CT technologist if there is any possibility that they may be pregnant. See the Safety page for more information about pregnancy and x-rays.

What does the equipment look like?

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

How does the procedure work?

In many ways CT scanning works very much like other x-ray examinations. Different body parts absorb the x-rays in varying degrees. It is this crucial difference in absorption that allows the body parts to be distinguished from one another on an x-ray film or CT electronic image.

In a conventional x-ray exam, a small amount of radiation is aimed at and passes through the part of the body being examined, recording an image on a special electronic image recording plate. Bones appear white on the x-ray; soft tissue, such as organs like the heart or liver, shows up in shades of gray, and air appears black.

With CT scanning, numerous x-ray beams and a set of electronic x-ray detectors rotate around you, measuring the amount of radiation being absorbed throughout your body. Sometimes, the examination 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, which 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 multislice CT or multidetector CT, allow thinner slices to be obtained in a shorter period of time, resulting in more detail and additional view capabilities.

Modern CT scanners are so fast that they 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 but especially children, the elderly and critically ill, all of whom may have difficulty in remaining 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 examination table, usually lying flat on your back. Straps and pillows may be used to help you maintain the correct position and to help you 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 contrast material is used, depending on the type of exam, it will be swallowed, injected through an intravenous line (IV) or, rarely, administered by enema.

Next, the table will move quickly through the scanner to determine the correct starting position for the scans. Then, the table will move slowly through the machine 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, whether breathing or 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 examination is completed, you will be asked to wait until the technologist verifies that the images are of high enough quality for accurate interpretation.

A CT scan of the head is usually completed within 10 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 scanning itself causes no pain, there may be some discomfort from having to remain still for several minutes. If you have a hard time staying still, are claustrophobic or have chronic pain, you may find a CT exam to be stressful. The technologist or nurse, under the direction of a physician, may offer you some medication to help you tolerate the CT scanning procedure.

If an intravenous contrast material is used, you will feel a pin prick when the needle is inserted into your vein. You will likely have a warm, flushed sensation during the injection of the contrast materials and a metallic taste in your mouth that lasts for at most a minute or two. You may experience a sensation like you have to urinate; however, this is actually a contrast effect and subsides quickly.

When you enter the CT scanner, special light lines may be seen projected onto your body, and are used to ensure that you are properly positioned. With modern CT scanners, you will hear only slight buzzing, clicking and whirring sounds 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 intravenous line used to inject the contrast material will be removed by the technologist, and the tiny hole made by the needle will be covered with a small dressing. You can return to your normal activities.

Who interprets the results and how do I get them?

A radiologist with expertise in supervising and interpreting radiology examinations will analyze the images and send an official report to your primary care physician or physician who referred you for the exam, who will discuss the results with you.

Follow-up examinations may be necessary. Your doctor will explain the exact reason why another exam is requested. Sometimes a follow-up exam is done because a potential abnormality needs further evaluation with additional views or a special imaging technique. A follow-up examination may also be necessary so that any change in a known abnormality can be monitored over time. Follow-up examinations are sometimes the best way to see if treatment is working or if a finding is stable or changed over time.

What are the benefits vs. risks?

Benefits

• 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.
• 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 Safety page for more information about radiation dose.
• Women should always inform their physician and x-ray or CT technologist if there is any possibility that they are pregnant. See the Safety 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 baby. This risk is, however, minimal with head CT scanning.
• Manufacturers of intravenous contrast indicate mothers should not breastfeed their babies for 24-48 hours after contrast medium is given. However, both the American College of Radiology (ACR) and the European Society of Urogenital Radiology note that the available data suggest that it is safe to continue breastfeeding after receiving intravenous contrast. For further information please consult the ACR Manual on Contrast Media and its references.
• The risk of serious allergic reaction to contrast materials that contain iodine is extremely rare, and radiology departments are well-equipped to deal with them.

• 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.

What are the limitations of CT Scanning of the Head?

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

Compared to MR imaging, the precise details of soft tissue (particularly the brain, including the disease processes) are less visible on CT scans. CT is not sensitive in detecting inflammation of the meninges—the membranes covering the brain.

Ultrasound - Abdomen

Ultrasound imaging of the abdomen uses sound waves to produce pictures of the structures within the upper abdomen. It is used to help diagnose pain or distention and evaluate the kidneys, liver, gallbladder, pancreas, spleen and abdominal aorta. Ultrasound is safe, noninvasive and does not use ionizing radiation.

This procedure requires little to no special preparation. Your doctor will instruct you on how to prepare, including whether you should refrain from eating or drinking beforehand. Leave jewelry at home and wear loose, comfortable clothing. You may be asked to wear a gown.

What is Ultrasound Imaging of the Abdomen?

Ultrasound is safe and painless, and produces pictures of the inside of the body using sound waves. Ultrasound imaging, also called ultrasound scanning or sonography, involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the probe through the gel into the body. The transducer collects the sounds that bounce back and a computer then uses those sound waves to create an image. Ultrasound examinations do not use ionizing radiation (as used in x-rays), thus there is no radiation exposure to the patient. Because ultrasound images are captured in real-time, they can show the structure and movement of the body's internal organs, as well as blood flowing through blood vessels.

Ultrasound imaging is a noninvasive medical test that helps physicians diagnose and treat medical conditions.

An abdominal ultrasound produces a picture of the organs and other structures in the upper abdomen.

A Doppler ultrasound study may be part of an abdominal ultrasound examination.

Doppler ultrasound, also called color Doppler ultrasonography, is a special ultrasound technique that allows the physician to see and evaluate blood flow through arteries and veins in the abdomen, arms, legs, neck and/or brain (in infants and children) or within various body organs such as the liver or kidneys.

What are some common uses of the procedure?

Abdominal ultrasound imaging is performed to evaluate the:

• kidneys
• liver
• gallbladder
• pancreas
• spleen
• abdominal aorta and other blood vessels of the abdomen

Ultrasound is used to help diagnose a variety of conditions, such as:

• abdominal pain or distention.
• abnormal liver function.
• enlarged abdominal organ.
• stones in the gallbladder or kidney.
• an aneurysm in the aorta.

Additionally, ultrasound may be used to provide guidance for biopsies.

Doppler ultrasound images can help the physician to see and evaluate:

• blockages to blood flow (such as clots)
• narrowing of vessels
• tumors and congenital vascular malformations
• reduced or absent blood flow to various organs
• greater than normal blood flow to different areas, which is sometimes seen in infections

Fistulogram/Sinogram

A fistulogram uses a form of real-time x-ray called fluoroscopy and a barium-based contrast material to produce images of an abnormal passage within the body called a fistula. Similarly, a sinogram assesses an abnormal passage called a sinus that originates or ends in one opening, often on the skin. Both examinations are used to assess and diagnose the size and shape of fistulas and sinuses and any related abscess and/or infection.

You will be instructed on how to prepare. You may be asked to refrain from eating or drinking anything for several hours before the examination, but you should be allowed to take medications with small amounts of clear fluid up to two hours prior. Tell your doctor if there’s a possibility you are pregnant and discuss any recent illnesses, medical conditions, medications you’re taking and allergies, especially to contrast materials. Leave jewelry at home and wear loose, comfortable clothing. You may be asked to wear a gown.

• What is a Fistulogram/Sinogram?
• What are some common uses of the procedure?
• How should I prepare?
• What does the equipment look like?
• How does the procedure work?

• How is the procedure performed?
• What will I experience during and after the procedure?
• Who interprets the results and how do I get them?
• What are the benefits vs. risks?
• What are the limitations of Fistulogram/Sinogram exams?

What is a Fistulogram/Sinogram?

A fistulogram is an x-ray procedure used to view a fistula, an abnormal passage between two or more anatomic spaces or organs or a pathway that leads from an internal cavity or organ to the surface of the body. A sinogram is a similar procedure done to assess a sinus, an abnormal passage or cavity that originates or ends in one opening, often on the skin. Contrast material is used to help identify the start of the fistula/sinus, its pathway and what organs are involved.

What are some common uses of the procedure?

A fistulogram/sinogram is used to diagnose and assess the size and shape of fistulas and sinuses and prepare a treatment plan.

Fistulas usually involve hollow organs like the intestines, bladder, urethra and vagina. They often form as a result of infection or inflammation related to surgery, injury or radiation therapy. They may also be related to inflammatory bowel conditions such as Crohn’s disease and ulcerative colitis.

Fistulograms are used to assess many types of fistulas, including those that form between:

• two loops of intestine
• the anal canal and skin near the anus
• the vagina and another body part such as the colon, rectum, small intestine or bladder.

Fistulograms may also be used to assess abscess collections post-drainage and to determine whether there is a persistent communication from the collection to any surrounding structures.

Additionally, fistulograms are used to assess deliberately created fistulas in people receiving kidney dialysis. Repeated dialysis can cause scarring and damage to the vein, and veins exposed to arterial pressure and turbulent blood flow can become narrowed due to thickening of the blood vessel. A fistulogram is needed to assess the problem with the dialysis access. These procedures are known as Fistula/Graft Declotting and Interventions.

Sinuses can occur throughout the body and may be related to infection or injury. Symptoms may be mild, such as a discharge of clear fluid from the skin, or more serious, such as abscess formation. A sinogram can show the extent of the problem and help develop a plan for future care.

How should I prepare?

You should inform your physician of any medications being taken and if there are any allergies, especially to iodinated contrast materials. Also inform your doctor about recent illnesses or other medical conditions.

Women should always inform their physician and x-ray technologist if there is any possibility that they are pregnant. Many imaging tests are not performed during pregnancy so as not to expose the fetus to radiation. If an x-ray is necessary, precautions will be taken to minimize radiation exposure to the baby. See the Safety page for more information about pregnancy and x-rays.

Instructions are typically provided prior to your exam. You may be asked to refrain from eating for six hours before the procedure but you may usually drink small amounts of clear fluid with medications up to two hours before the procedure.

What does the equipment look like?

The equipment typically used for this examination consists of a radiographic table, one or two x-ray tubes and a television-like monitor that is located in the examining room. Fluoroscopy, which converts x-rays into video images, is used to watch and guide progress of the procedure. The video is produced by the x-ray machine and a detector that is suspended over a table on which the patient lies.

The radiologist typically will introduce contrast material into the fistula/sinus with a thin plastic tube called a catheter.

How does the procedure work?

X-rays are a form of radiation like light or radio waves. X-rays pass through most objects, including the body. Once it is carefully aimed at the part of the body being examined, an x-ray machine produces a small burst of radiation that passes through the body, recording an image on photographic film or a special detector.

Different parts of the body absorb the x-rays in varying degrees. Dense bone absorbs much of the radiation while soft tissue, such as muscle, fat and organs, allow more of the x-rays to pass through them. As a result, bones appear white on the x-ray, soft tissue shows up in shades of gray and air appears black.

Until recently, x-ray images were maintained on large film sheets (much like a large photographic negative). Today, most images are digital files that are stored electronically. These stored images are easily accessible and are frequently compared to current x-ray images for diagnosis and disease management.

Fluoroscopy uses a continuous or pulsed x-ray beam to create a sequence of images that are projected onto a fluorescent screen, or television-like monitor. When used with a contrast material, which clearly defines the area being examined by making it appear dark (or by electronically reversing the image contrast to white), this special x-ray technique makes it possible for the physician to view joints or internal organs in motion. Still images or movies are also captured and stored electronically on a computer.

How is the procedure performed?

You may be asked to change into a hospital gown. You also may receive an intravenous (IV) line in your arm for the delivery of painkillers and/or sedatives to help make you more comfortable during the procedure.

You will be taken into the x-ray room where the technologist will position you on the x-ray table. You may be asked to wear a lead shield to help protect certain parts of your body. The x-ray machine will be positioned so that the radiologist can easily view the contrast material-enhanced fistula/sinus.

The area around the fistula/sinus will be cleaned with an antiseptic solution. Occasionally, a local anesthetic is injected into the area.

The radiologist will use the x-ray equipment to guide the catheter into the fistula/sinus or artery/vein using a needle and guide wire. When the catheter is in the correct place, the radiologist will inject contrast material through the catheter. X-rays will be taken to show where the fistula/sinus goes or where the blockage is located in a dialysis-related fistula.

You must hold very still and may be asked to keep from breathing for a few seconds while the x-ray picture is taken to reduce the possibility of a blurred image. The technologist will walk behind a wall or into the next room to activate the x-ray machine.

When all the x-rays have been taken, the catheter will be removed. If your fistula/sinus has an opening on the outside of the body, your wound site will be cleaned and your skin will be covered with a sterile dressing. A nurse may apply pressure over the puncture site for several minutes to prevent any bleeding. You may receive one or two stitches at the puncture site. If your fistula/sinus is inside your rectum or vagina, you will be able to use the bathroom to pass any remaining contrast.

Depending on departmental policy, some hospitals will allow a guardian to accompany the child into the x-ray room. The guardian will be asked to wear a lead apron to protect certain parts of his or her body. A lead shield may also be used to protect their child’s reproductive organs as much as possible from radiation exposure.

Children in the hospital who cannot be brought to the x-ray room can be x-rayed at their bedside with a portable device.

The x-ray technologist will position the child, and then walk behind a wall or into the next room to activate the x-ray machine. The child must remain still to reduce the possibility of blurring the image. Older children will be asked to hold their breath and stay still for a few seconds during the x-ray, while infants may need to be gently restrained.

See the Children and Radiation Safety page for more information.

What will I experience during and after the procedure?

You may experience slight discomfort when the IV line is placed in your arm or when local anesthetic is injected in the area of your fistula/sinus. You may feel a warm sensation as the contrast material is injected into your fistula/sinus. While you may experience discomfort during the procedure, there is usually no pain.

If you are a dialysis patient with narrowing in a deliberately created fistula, the radiologist may put a catheter with a balloon at the tip into the area of stenosis. The radiologist will inflate the balloon to stretch the narrowing and enlarge the fistula. You may feel some pressure in that area when this happens. Sedation medicine is usually given for this portion of the procedure.

The procedure itself will take approximately 30 minutes, and you should expect to spend about an hour in the x-ray department. You may be asked to stay in the facility for one to two hours to recover. During this time, your nurse will check your fistula or sinus area for any bleeding.

There may be some restrictions on your activities for 24 hours after your procedure. For instance, you may be advised to avoid: driving or using any heavy machines; drinking alcohol or taking any medicines that make you drowsy; lifting anything heavy; or wearing tight clothes or jewelry that will press on your wound.

You can return to your normal activities 24 hours after your procedure.

Who interprets the results and how do I get them?

A radiologist, a physician specifically trained to supervise and interpret radiology examinations, will analyze the images and send a signed report to your primary care or referring physician, who will discuss the results with you.

What are the benefits vs. risks?

Benefits

• Radiologic examinations can often provide enough information to avoid more invasive procedures.
• A fistulogram/sinogram can give your doctors precise information to help develop the best treatment plan for you.
• Fistulograms/sinograms provide real-time images that may be evaluated immediately.
• No radiation remains in a patient's body after an x-ray examination.
• X-rays usually have no side effects in the typical diagnostic range for this exam.

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.
• Women should always inform their physician or x-ray technologist if there is any possibility that they are pregnant. See the Safety page for more information about pregnancy and x-rays.
• You may experience minor pain, bruising and/or infection from the catheter insertion that may require treatment with antibiotics.
• Rarely, you may experience an allergic reaction to the contrast material. This could result in a rash, hives, itching, nausea, fainting or shortness of breath. Medication may be given to relieve this. Contact your doctor if you have any of these symptoms.
• There may be a small amount of bleeding from the fistula/sinus for a short time after the procedure.

What are the limitations of Fistulogram/Sinogram exams?

Fistulograms/sinograms may not be possible in every patient due to medical and/or technical reasons.

The procedure may fail to define the presence of disease upstream or downstream from the fistula, which may be necessary for appropriate treatment planning.

The procedure may fail to provide the anatomic location of the fistula within the gastrointestinal tract. Edema, debris, or a large abscess may hinder fistulograms by blocking the flow of contrast material. Fistulograms are not recommended if sepsis is present—a potentially life-threatening response to infection.

Often, information concerning potential fistulas or sinuses and their communications can be obtained from CT scans performed after ingestion of oral contrast. Contrast-enhanced CT may be able to identify connections from the bowel to any surrounding structures or skin.