CT Scans and MRI Tests

CT (computed tomography, or CAT) scans and MRI (magnetic resonance imaging) tests may be used to detect any problems with the structure or position of the heart, lungs, or blood vessels. The CT scan and the MRI provide a much clearer picture of your organs than an x-ray. These tests are sometimes used to avoid the potential risk of other invasive heart tests, such as angiography. Some of these tests are done by injecting through a needle a small amount of radioactive material into a vein.

CT scans use a unique x-ray machine that makes a circle around your body. Using measurements from every angle around this circle, the computer takes pictures, each showing a slightly different "slice" or "cross-section" of your body. MRI is often more costly and time-consuming, but it is preferred over other non-invasive heart tests. This is because MRI provides detailed pictures of the heart and blood vessels, shows the heart from many different views, clearly shows blood vessels, identifies structures (like clots) from moving blood, and helps to better understand findings from X-rays or CT scans. The main discomfort with CT scans and MRI is the closed in, or claustrophobic, feeling that some people have from being inside the scanner. An MRI may require you to lie still in the scanner for at least one hour. But, a technician watches you during the test and may enter the room to speak to you or may speak with you over an intercom in the MRI machine.