Doctors use magnetic resonance imaging, or MRI, to view damaged areas of the brain they can't see with other techniques such as computed tomography, allowing them to diagnose more than 90 percent of people they suspect have multiple sclerosis, according to WebMD. Doctors also use MRIs to track the progression of the disease and to judge the effectiveness of medications they prescribe to treat multiple sclerosis.
Magnetic resonance imaging uses large magnets, computers and radio waves to detect changes in the brain or spinal cord that may be related to multiple sclerosis, states WebMD. Doctors consider MRIs to be the best way to detect multiple sclerosis, though 5 percent of people with the disease have negative scans that miss disease-related abnormalities. MRIs take approximately 40 to 80 minutes, and technicians may take dozens of images during the test.
Depending on the type of MRI that doctors order to diagnose multiple sclerosis, they may first inject patients with a contrasting material to enhance the images the test produces, notes WebMD. MRIs do not pose a safety risk for most patients, including those that have artificial joints and staples, as the metals used in these devices are not magnetic. People who have pacemakers, insulin pumps and cochlear implants; women who are pregnant; and people with lung diseases should tell their doctors before undergoing MRIs.