Regular X-rays may show a broken leg or fractured arm clearly. But, sometimes, doctors need other ways to see what’s happening inside your body. Today, several technologies can provide doctors with up-close views of different tissues, blood vessels or organs. Here’s a guide to scans doctors commonly recommend to help diagnose an illness or determine the best course of treatment.
For a computed tomography (CT) scan, you lie on a table that slides into the scanner. A device rotates around you, emitting X-rays. Your tissues absorb some of the X-rays, and the scanner detects the ones that pass through. A computer turns this information into cross-sectional pictures. These “slices” can be stacked to form a three-dimensional image.
Doctors use CT scans to examine blood vessels and organs, look for tumors, diagnose injuries and locate the right site for a biopsy. CT scans provide clearer pictures of more tissue types than traditional X-rays do.
You also lie on a table that slides into a scanner for magnetic resonance imaging (MRI). Magnets in the machine make hydrogen atoms in your body align in a certain way. Then, the machine emits radio waves, which bounce off tissues. The machine creates two- and three-dimensional images from the returning signals.
Doctors often use MRIs for the same reasons as CT scans. However, MRIs are better at creating detailed images of knee joints or areas having soft tissue.
A positron emission tomography (PET) scan begins with a small amount of radioactive tracer that’s injected into a vein. Then, you lie on a table that slides into the scanner. The scanner detects positrons, tiny particles emitted by the tracer. A computer converts these signals into an image.
A PET scan shows the size, shape and position of tissues and how they’re working. Doctors use the scans to look for activity that indicates disease, such as tumor growth or impaired blood flow to the heart.