ASSESSMENT OF MRI CRITERIA FOR A DIAGNOSIS OF MS

To test the reliability of four previously proposed MRI criteria for t he diagnosis of MS, we reviewed 1,500 consecutive brain scans for the presence, number, size, and location of areas of increased signal (AIS ) on proton-density and T2-weighted images, unaware of the patients' c linical presentations and ages. This series included 134 subjects with a clinical diagnosis of MS. Relying exclusively on the presence of at least three or four AIS for a positive diagnosis of MS resulted in hi gh sensitivity (90% for three AIS and 87% for four) but inadequate spe cificity (71% for three AIS and 74% for four) and positive predictive value (23% for three AIS and 25% for four). If one of these lesions wa s required to border the lateral ventricles, specificity was 92% and p ositive predictive value was 50% at a sensitivity of 87%. Using the Fa zekas criteria (at least three AIS and two of the following features: abutting body of lateral ventricles, infratentorial lesion location, a nd size >5 mm) led to a further highly significant improvement of spec ificity (96%; p = 0.0000) and increase of the positive predictive valu e (65%) at the expense of a less significant decrease in sensitivity ( 81%; p < 0.01).