CT (CAT Scan)
What
is CT and how does it work?
What to expect during a CT exam and to prepare
CT of the Head, Neck, Eye and Sinus
CT of the Chest, Abdomen and Pelvis
CT of the Cervical, Thoracic and Lumbar Spine
CT of the Upper and Lower Extremities
CT Angiogram
CT Pulmonary Embolism
CT Cardiac Scoring
What is CT and how does it work?
CT (computed tomography, CAT scan) is an imaging exam which uses highly
sophisticated x-ray equipment to obtain image data from different angles
around the body and then uses computer processing of the information to
show a cross-section of body tissues and organs. The CT scan itself is
painless.
CT imaging can show several types of tissue—lung, bone, soft tissue and
blood vessels—with great clarity. Using specialized equipment and medical
expertise to create and interpret CT scans of various sections of the body,
TRA’s board certified radiologists can more easily diagnose problems
such as cancers, cardiovascular disease, infectious disease, trauma and musculoskeletal
disorders.
What to expect during a CT exam and how to prepare
- Before your exam, a CT technologist will review
your medical and allergy history, and answer any questions
you might have. He or she will keep you informed
and assist you throughout your study. Because CT involves x-ray,
please notify your technologist if you think you might be pregnant.
- If you have had previous allergic reactions to contrast agents or
are diabetic, please see the exam
safety section of our website.
- Please wear comfortable, loose clothing for your scan. You may be asked
to change into a gown before your exam to avoid possible interference
from any metal in your clothing.
Some CT exams require that you drink a flavored oral contrast agent.
It is important that you drink it one hour before your appointment
time (not your check-in time). Oral contrast can be picked up in advance
at TRA Medical
Imaging’s Tacoma, Lakewood or Gig Harbor offices if you prefer
to drink it at home before traveling to your appointment.
- If you will be having oral contrast, please do not eat or drink four
hours prior to your exam.
- Some CT exams involve an intravenous (IV) contrast injection (usually
placed in the arm) to enhance the results of the study. The contrast
may make you feel warm or create a strange taste in your mouth. This feeling
lasts only
a few moments. Less commonly, it may make you feel nauseous.
- You will be asked to lie on a comfortable scanning bed and although
most patients lie on their backs, your position may vary due to the type
of exam you are having. Although the actual scans are very fast, the time
you
will spend
on the scanning bed is generally between 10 and 30 minutes,
again depending on the type and number of exams you will have. Because
lying still
is important
for excellent image quality, children need to be able to lie
still for up to five minutes.
Let the technologist know of any of the following:
-
Allergies to latex or iodine
-
Previous reactions to contrast agent
-
Kidney problems
-
Diabetic medication you take
-
If you are pregnant or think you may be
-
If you ate or drank before the test
CT of the Head, Neck, Eye and Sinus
A tipped back head position may be required during imaging.
CT of the head, neck and eye (orbit) is frequently used
to evaluate abnormalities following traumatic head injury. Brain ventricles,
bony orbits (eye sockets), structures of the neck and lymph nodes are
well seen with CT. This exam may involve IV contrast to produce an image
that is more clearly defined. Because motion can distort CT images, the
back of your head may be positioned in a holder to keep your head immobilized
for a head, neck or eye CT exam. Your face will not be covered.
CT is usually an excellent scan for the sinus cavities
because the images are so well delineated.
CT of the Chest, Abdomen and Pelvis
You will be asked to lie on your back with your arms positioned
over your head for these scans.
CT of the chest may require IV administration of a contrast
media (contrast reactions or allergies)
to image the lungs, bronchi, as well as the esophagus, midline chest structures
including the ascending aorta, superior vena cava and diaphragm. You will
be asked to hold your breath for about 20-30 seconds for a chest CT.
CT of the abdomen and pelvis usually requires both IV and
oral contrast. For CT of the abdomen, multiple images are taken of the
liver, pancreas, spleen, aorta, vena cava vessels, kidneys and retroperitoneal
area. Pelvic CT images include the lower abdomen (pelvis) to demonstrate
possible abnormalities in the prostate, uterus, ovaries and bladder.
CT of the Cervical, Thoracic and Lumbar Spine
CT of the spine is used to evaluate spinal stenosis, disc
herniation and degenerative disc disease.
CT of the Upper and Lower Extremities
CT of the extremities produce images of your left or right
hand, wrist, foot, ankle, knee, or leg. It may be used to
evaluate fractures, soft
tissue masses
or to detect metastatic bone tumors.
CT Angiogram
For this exam, you will have a CT scan of the chest. CT
angiogram is the use of general CT imaging techniques to obtain images
of blood
vessels. CT angiogram
is most frequently used to detect a suspected blood clot
in the lungs (CT
pulmonary angiogram). It may also be used to evaluate cerebral
aneurysm or blood vessels
in the abdomen or legs.
A CT pulmonary angiogram involves injecting IV contrast
(contrast reactions or allergies) into a vein in the arm.
CT Pulmonary Embolism
CT scans are especially helpful in diagnosing or ruling
out pulmonary embolisms—a
sudden blockage of the blood flow in an artery in the lung, most commonly caused
by a blood clot, tumor or even fat.
CT Cardiac Scoring
CT coronary artery scoring is a test used to detect early
signs of coronary artery disease, or the build-up of plaque in the blood
vessels. It will provide your healthcare provider with both the location
of any plaque, as well as a score that indicates the extent of calcified
plaque. Scores range from 0 to 400+, indicating the evidence of plaque
to either no evidence, minimal, mild, moderate or extensive evidence of
plaque.
The exam itself takes five to 10 minutes. You will be asked
to lie on your back and small electrodes will be attached to your chest
to measure the electrical activity of your heart with an ECG (electrocardiogram)
machine. You will be asked to hold your breath for periods of 20 to 30
seconds while the images are recorded.
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