Patient Education - Lung Cancer Program at UCLA
yourself about lung cancer:
Thoracic CT is a computed tomography scan of the chest and upper abdomen.
Chest CT; CT scan - lungs; CT scan - chest
How the Test is Performed
You will be asked to lie on a narrow table (gantry) that slides into the center of
the scanner. Depending on what is being scanned, you may lie on the stomach, back,
or side. If contrast media (dye) is to be given, an IV (intravenous needle or tube)
will be placed in a small vein of your hand or arm.
As with standard photography, if you move while the CT image is being taken, it
will blur. Because of this, the operator of the scanner will tell you when to hold
your breath and not move.
As the exam takes place, the gantry will advance small intervals through the scanner.
Modern spiral scanners can perform the examination in one continuous motion of the
gantry. Generally, complete scans will only take a few minutes. However, additional
contrast-enhanced or higher-resolution scans will add to the scan time. The newest
multi-detector scanners can image the entire body, head-to-toe, in under 30 seconds.
How to Prepare for the Test
The health care provider may advise you to avoid eating or drinking for 4 - 6 hours
prior to the scan, if contrast dye is to be used.
The CT scanner has a weight limit to prevent damage to the mechanized gantry.
Have the health care provider contact the scanner operator if you weigh more than
Metal interferes with the x-rays, so you may be asked to remove jewelry and wear
a hospital gown during the study.
How the Test Will Feel
The x-rays are painless. The primary discomfort may be from the need to lie still
on the table.
If intravenous contrast dye is given, you may feel a slight burning sensation
in the injected arm, a metallic taste in the mouth, and a warm flushing of the body.
These sensations are normal and usually go away within a few seconds.
Why the Test is Performed
Thoracic CT may be recommended when there is a need for examination of the structures
inside the chest. It is noninvasive and poses less risk than invasive procedures
(such as angiography or exploratory surgery).
Common indications for thoracic CT include:
- When there is a chest injury
- When a tumor or mass (clump of cells) is suspected
- To determine the size, shape, and position of internal organs
- To look for bleeding or fluid collections in the lungs or other areas
What Abnormal Results Mean
Thoracic CT may show many disorders of the heart, lungs, or chest area, including:
- Enlarged lymph nodes (lymphadenopathy)
- Abnormalities of the structure or position of the heart, lungs, or blood vessels
- Tumors, nodules, or cysts within the chest
- The stage of some lung tumors or esophageal cancer
- Aortic aneurysm (thoracic)
- Pleural effusion
- Accumulations of blood or fluid
Additional conditions under which the test may be performed:
- Alcoholic cardiomyopathy
- Atrial myxoma
- Cardiac tamponade
- Coarctation of the aorta
- Dilated cardiomyopathy
- Heart failure
- Hypertensive heart disease
- Idiopathic cardiomyopathy
- Infective endocarditis
- Ischemic cardiomyopathy
- Left-sided heart failure
- Mesothelioma (malignant)
- Metastatic cancer to the lung
- Mitral regurgitation; acute
- Mitral regurgitation; chronic
- Mitral valve prolapse
- Pericarditis; bacterial
- Pericarditis; constrictive
- Pericarditis; post-MI
- Peripartum cardiomyopathy
- Pulmonary edema
- Restrictive cardiomyopathy
- Senile cardiac amyloid
- SVC obstruction
CT scans and other x-rays are regulated to provide the minimum amount of radiation
exposure needed to produce the image. During pregnancy, a thoracic CT scan is not
recommended unless the benefits outweigh the risk of radiation exposure to the fetus.
CT scans provide low levels of radiation.
The most common dye used is iodine-based. A person who is allergic to iodine may
experience nausea, vomiting, sneezing, itching, or hives, and occasionally anaphylaxis
(life-threatening allergic response ). In people with kidney problems, the dye may
have toxic effects on the kidneys.
The benefits of a CT scan usually far outweigh the risks. A CT scan is one of
the best ways of looking at soft tissues such as the heart and lungs.
Review Date: 8/3/2005
Reviewed By: Jonathan Gross, M.D., Department of Radiology, Columbia University Medical
Center, New York, NY. Review provided by VeriMed Healthcare Network.
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