Topic Overview

An MRI scan is the best way to locate multiple sclerosis (MS) lesions (also called plaques) in the brain or spinal cord. An MRI scan is abnormal in more than 95% of people recently diagnosed with MS.^{footnote 1}

But abnormal MRI results do not always mean that you have MS. Abnormalities show up on scans from many illnesses other than MS. An abnormal finding on an MRI scan alone is not enough to diagnose MS. Your doctor will confirm a diagnosis of MS based on your symptoms, your neurological exam, and the results from an MRI and other tests.

When abnormal MRI results occur along with a medical history, abnormal nervous system exam, and other test results that are typical of MS, it is very likely that you have MS.

If you have already been diagnosed with MS, MRI scans can sometimes distinguish new lesions from older ones and can help your doctor(s) follow the progress of the disease. Continuing to have periodic MRI scans if you have relapsing-remitting MS may help identify new lesions even when you are not having symptoms from those new lesions.

If you have had just one episode of MS-like symptoms and are trying to decide whether to start treatment with medicine, MRI scans can be helpful in assessing the progress of the disease. If new lesions are developing or if existing lesions are growing—regardless of whether you have had further episodes of MS symptoms—most doctors will recommend that you begin treatment.