T1-Hypointense Lesions (T1 Black Holes) in Mild-to-Moderate Disability Relapsing Multiple Sclerosis

Abstract

T1 -hypointense lesions (T1-black holes) in multiple sclerosis (MS) are areas of relatively severe central nervous system (CNS) damage compared with the more non-specific T2-hyperintense lesions, which show greater signal intensity than normal brain on T2-weighted magnetic resonance imaging (MRI). The T1-hypointense lesions are areas of axonal loss, as well as matrix disruption [1, 2]. T1-hypointense lesions are moderately correlated with focal reduction in the magnetization transfer index [3, 4] and reduced N-acetylaspartate (NAA) [2]. T1hypointense lesions appear to evolve from only a subset of prior enhancing MS lesions. Recent studies have suggested that an increase in T1-hypointense lesions is more strongly correlated with progression of disability in secondary progressive MS than T2-hyperintense lesions [5, 6]. For these reasons, the T1 -hypointense lesions are considered to be potential independent markers of the MS disease process compared with the conventional MR measures of subclinical disease --- the T2-lesions, and markers of inflammation, the enhancing lesions [7, 8]. Here we summarize the analyses of T1-black holes from the MS Collaborative Research Group Trial of interferon $β$-1a, which provided an opportunity to determine the natural history of T1-black holes in relatively early MS, in patients with only mild-to-moderate disability, and to evaluate the potential of T1-black holes as a measure of treatment efficacy. Details of this work have been published previously [9].