What is the difference between a CT scan and an MRI?

Both CT scans and MRIs are imaging tests that create pictures of areas inside your body to help your doctor see whether a tumor is present. They work in different ways.

A CT scan uses an X-ray machine linked to a computer to take a series of pictures from different angles, creating detailed 3-D images. Sometimes a dye called contrast material is used to highlight certain areas.

An MRI uses a powerful magnet and radio waves—not X-rays—to take pictures of the body in slices. A special dye can make tumors show up brighter.

Your doctor chooses the test, or combination of tests, that will give the clearest information for your situation. Your healthcare team can explain why a particular scan was ordered for you.