Both CT and MRI scans are types of imaging studies that produce cross-sectional images of the inside of the body for diagnostic purposes, explains the American Academy of Orthopaedic Surgeons. A CT scan produces the images through a combination of X-rays and computer technology, while an MRI doesn't use radiation.
"CT" stands for computed tomography, notes the American Academy of Orthopaedic Surgeons. With the help of computer technology, a CT scan provides the physician with more detailed images of the inside of the patient's body than a standard X-ray is able to provide. During a CT scan, the patient lies as still as possible while a X-ray tube turns slowly around the body to capture images from every direction. A computer then compiles the images into a two-dimensional view of the area of the body being examined. Patients sometimes receive instructions to ingest barium sulfate prior to their CT scans so that certain internal structures show up more clearly on the images.
"MRI" is short for magnetic resonance imaging, states the AAOS. An MRI machine utilizes magnetic fields in place of X-ray radiation. The patient lies inside of a tube-shaped scanner, which surrounds the body with a magnetic field and then directs radio waves toward the area of the body being scanned, causing the tissues to give off vibrations. Sophisticated computer technology then translates data from the vibrations into an image for the physician to view.