Cerebral lesions of multiple sclerosis: is gadolinium always irreplaceable in assessing lesion activity?

We aimed to identify imaging characteristics on conventional magnetic resonance imaging that could predict multiple sclerosis (MS) brain lesion activity without contrast media administration. Magnetic resonance data sets of forty-two patients with relapsing-remitting MS who presented symptoms or signs suggestive of new disease activity were retrospectively reviewed. We classified the MS lesions into three types according to different patterns present on T2-weighted images and evaluated their relationship with the contrast uptake. Evolving aspects of each type of lesion were observed in 18 patients during a follow-up period ranging from nine to 36 months. On T2-weighted images, only the pattern consisting of a thin border of decreased intensity compared with the lesion's center and perifocal edema (Type II) reached diagnostic accuracy in terms of its relationship with gadolinium enhancement (P = 0.006). The sensitivity was 0.461, and the specificity was 0.698. In contrast, enhancement was not significantly related to the pattern consisting of a lesion center that was homogeneously brighter than its periphery (Type I) or less-hyperintense T2 focal lesions with either homogeneous or inhomogeneous center (Type III) (P > 0.05 for both). The assessment of MS lesion activity should include a careful evaluation of T2-weighted images in addition to contrast enhancement assessment. The presence of an accompanying peripheral thin rim of hypointensity on T2-weighted images related best with contrast enhancement and subsequent lesion activity and may represent an additional pattern for disease activity assessment when gadolinium examination is contraindicated or influenced by prior therapy.