A chest CT (computed tomography) scan is an imaging method that uses x-rays to create cross-sectional pictures of the chest and upper abdomen.
Thoracic CT; CT scan - lungs; CT scan - chest
How the Test is Performed
The test is done in the following way:
The complete scan takes 30 seconds to a few minutes.
Certain CT scans require a special dye, called contrast, to be delivered into the body before the test starts. Contrast highlights specific areas inside the body and creates a clearer image. If your provider requests a CT scan with intravenous contrast, you will be given it through a vein (IV) in your arm or hand. A blood test to measure your kidney function may be done before the test. This test is to make sure your kidneys are healthy enough to filter the contrast.
You may be given medicine to help you relax during the test.
How to Prepare for the Test
Some people have allergies to IV contrast and may need to take medicine before their test to safely receive this substance.
Contrast can be given in several ways, depending on the type of CT being performed.
If contrast is used, you may also be asked not to eat or drink anything for 4 to 6 hours before the test.
If you weigh more than 300 pounds (135 kilograms), have your health care provider contact the scanner operator before the exam. CT scanners have an upper weight limit of 300 to 400 pounds (100 to 200 kilograms). Newer scanners can accommodate up to 600 pounds (270 kilograms). Because it is hard for x-rays to pass through metal, you will be asked to remove jewelry.
How the Test will Feel
Some people may have discomfort from lying on the hard table.
Contrast given through an IV may cause a slight burning sensation, 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.
There is no recovery time, unless you were given medicine to relax. After a CT scan, you can go back to your normal diet, activity, and medicines.
Why the Test is Performed
CT quickly creates detailed pictures of the body. The test may be used to get a better view of the structures inside the chest. A CT scan is one of the best ways of looking at soft tissues such as the heart and lungs.
A chest CT may be done:
What Abnormal Results Mean
Thoracic CT may show many disorders of the heart, lungs, or chest area, including:
CT scans and other x-rays are strictly monitored and controlled to make sure they use the least amount of radiation. CT scans use low levels of ionizing radiation, which has the potential to cause cancer and other defects. However, the risk from any one scan is small. The risk increases as many more studies are done.
In some cases, a CT scan may still be done if the benefits greatly outweigh the risks. For example, it can be more risky to not have the exam if your provider thinks you might have cancer.
The most common type of contrast given into a vein contains iodine. If a person with an iodine allergy is given this type of contrast, nausea, sneezing, vomiting, itching, or hives may occur. In rare cases, the dye can cause a life-threatening allergic response called anaphylaxis. If you have any trouble breathing during the test, you should notify the scanner operator immediately. Scanners come with an intercom and speakers, so the operator can hear you at all times.
In people with kidney problems, the dye may have harmful effects on the kidneys. In these situations, special steps may be taken to make the contrast dye safer to use.
Shaqdan KW, Otrakji A, Sahani D. Safe use of contrast media. In: Abujudeh HH, Bruno MA, eds. Radiology Noninterpretive Skills: The Requisites. Philadelphia, PA: Elsevier; 2018:chap 20.
Shaw AS, Prokop M. Computed tomography. In: Adam A, Dixon AK, Gillard JH, Schaefer-Prokop CM, eds. Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging. 6th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2015:chap 4.
Review Date: 7/20/2018
Reviewed By: Allen J. Blaivas, DO, Division of Pulmonary, Critical Care, and Sleep Medicine, VA New Jersey Health Care System, Clinical Assistant Professor, Rutgers New Jersey Medical School, East Orange, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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