A computed tomography (CT) scan of the sinus is an imaging test that uses x-rays to create detailed pictures of the air-filled spaces inside the face (sinuses).
CAT scan - sinus; Computed axial tomography scan - sinus; Computed tomography scan - sinus; CT scan - sinus
You will be asked to lie on a narrow table that slides into the center of the CT scanner. You may lie on your back, or you may lie face-down with your chin raised.
Once you are inside the scanner, the machine's x-ray beam rotates around you. (Modern "spiral" scanners can perform the exam without stopping.)
A computer creates separate images of the body area, called slices. These images can be stored, viewed on a monitor, or printed on film. Three-dimensional models of the body area can be created by stacking the slices together.
You must be still during the exam, because movement causes blurred images. You may be told to hold your breath for short periods of time. Straps and pillows may be used to keep you still during the procedure.
The actual scan should take about 5 minutes. The entire process should take 15 minutes.
Certain exams require a special dye, called contrast, to be delivered into the body before the test starts. Contrast helps certain areas show up better on the x-rays.
If you weigh more than 300 pounds, find out if the CT machine has a weight limit. Too much weight can cause damage to the scanner's working parts.
You will be asked to remove jewelry and wear a hospital gown during the study.
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.
CT rapidly creates detailed pictures of the sinuses. The test may diagnose or detect:
This results from this test may also help your health care provider plan for sinus surgery.
Results are considered normal if the sinuses are normal in appearance.
Abnormal results may be due to:
Risks of CT scans include:
CT scans do expose you to more radiation than regular x-rays. Having many x-rays or CT scans over time may increase your risk for cancer. However, the risk from any one scan is small. You and your doctor should weigh this risk against the benefits of getting a correct diagnosis for a medical problem.
Some people have allergies to contrast dye. Let your doctor know if you have ever had an allergic reaction to injected contrast dye.
Rarely, the dye may 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.
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Grainger RG, Thomsen HS, Morcos SK, Koh D, Roditi G. Intravascular contrast media for radiology, CT, and MRI. In: Adam A, Dixon AK, eds. Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging. 5th ed. New York, NY: Churchill Livingstone; 2008:chap 2.
Shaw AS, Dixon AK. Multidetector computed tomography. In: Adam A, Dixon AK, eds. Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging. 5th ed. New York, NY: Churchill Livingstone; 2008:chap 4.