Using MRI to Diagnose Multiple Sclerosis
Christopher T. Bever, Jr., MD, MBA
VA Medical Center, Baltimore, MD
MRI is used in the diagnosis of MS and also in monitoring disease activity. MRI is the most sensitive way of imaging MS lesions. Most of the current evidence on the usefulness of MRI relates to suspected cases of MS. Evidence-based practices have been developed for the use of MRI in the diagnosis of MS but no such guidance is available for patients with established disease.
There currently exist two different criteria for the use of MRI in diagnosing MS: the McDonald Criteria and the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology.
The McDonald Criteria were developed in April 2001 by an international panel in association with the NMSS of America, modified in 2005, and revised in 2010. The McDonald Criteria is so named after the lead author. The criteria make use of advances in MRI imaging techniques and are intended to replace the Poser Criteria and the older Schumacher Criteria. The McDonald Criteria are discussed in another article on this website. In brief, the McDonald Criteria address MRI evidence of dissemination in space and dissemination in time.
Evidence of dissemination in space requires three of the following four items:
≥ 1 T2 lesion in at least two out of four areas of the CNS: periventricular, juxtacortical, infratentorial or spinal cord.
Evidence of dissemination in time requires one of the following:
-A new T2 and/or gadolinium-enhancing lesion(s) on follow-upo MRI with reference to a baseline scan
The Utility of MRI in Suspected MS: Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology generated three Type A recommendations in the use of MRI finding:
>The finding of three or more T2 hyperintense lesions in patients with a clinically isolated syndrome (presented with a new neurologic deficit) was a very sensitive predictor for the development of clinically defined MS within 7-10 years.
>The appearance of new T2 hyperintense lesions or new contrasting enhancing lesions three or more months after a clinically isolated episode is highly predictive of the subsequent development of clinically defined MS in the near term.
>The probability of making a diagnosis other than MS in patients who presented with a clinically isolated syndrome and any of the above described MRI abnormalities is quite low once alternative diagnosis that mimic MS have been excluded.
Evidence-based criteria are not available for the use of MRI scans in patients with established MS. In general, MRI scans are obtained only when the results of the scan would cause a change in patient treatment. Although, this sounds straightforward, decisions are complicated by the fact the current disease modifying therapies that are available are not 100% effective, therefore new lesions may be found in patients who are benefiting from treatment.
Last Updated: March 2011