Cystic fibrosis (CF) is a disease caused by mutations in the CFTR gene, which lead to irregularities in how salt and water flow in and out of cells. This ultimately results in the buildup of thick, sticky mucus in different tissues and organs. In the lungs, this mucus makes breathing more difficult, and patients more susceptible to respiratory infections.
A computerized tomography (CT) scan — sometimes called a “CAT scan” — is considered the gold standard for identifying structural damage to the lungs in CF. CT scans also may be used to help diagnose CF.
What is a CT scan?
A CT scan uses a series of X-rays from multiple angles to build a three-dimensional image of the body’s bones, blood vessels, and soft tissues. The scan usually takes about 30 minutes, and can be performed at hospitals or clinics.
The machine used to do a scan typically looks kind of like a donut surrounding a table. The patient lies on the table, which moves through the ring as the X-ray images are taken. It is important that patients not wear anything metal (such as jewelry, glasses, hearing aids, and underwire bras) when they are scanned, as these can interfere with the images.
Some CT scans require patients to take a contrast agent — essentially a dye that can be seen easily in the scan — before the scan begins. Depending on the details of the scan, contrast agents may be taken by mouth, enema (through the rectum), or injection.
Of note, a CT scan involves more radiation than a standard X-ray, since it collects more-detailed information. It specifically uses ionizing radiation — high-energy wavelengths that penetrate tissue to reveal the body’s internal structures —that may increase the chance of developing cancer when used in high doses, but the risk associated with a single CT scan is quite small.
How CT scans are used in CF
CF causes the buildup of mucus in the lungs, airways, and nasal passages. This mucus can be visualized on CT scans.
CT scans of the lungs can identify bronchiectasis — a thickening of the walls of the small airways called bronchi — that is indicative of inflammation, and is considered a cardinal sign of CF-related lung damage.
CT scans also can show thickening of the airways and other structural abnormalities that can develop when the lung is damaged.
Because these imaging features correlate with clinical factors like lung function, CT scans often are used to monitor the clinical status of people with CF. They also can be used to monitor the effects of treatments.
Last updated: Sept. 15, 2021
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