Direct MRI detection of impending plaque development in multiple sclerosis

Objectives: To detect and localize MRI signal changes prior to the parenchymal contrast enhancement that classically defines the radiologic onset of the developing white matter lesion in multiple sclerosis (MS). Methods: We reviewed 308 high-resolution (#1 mm3 voxels) MRI scans at 3T and 7T in 29 patients with active MS. The presence of pre-parenchymal enhancement abnormalities before the appearance of parenchymal enhancement was evaluated in all available scans. Results: Pre-enhancement signal changes were noted in 26 of 162 enhancing lesions (16%) as linear enhancement of the central vein and/or perivenular hyperintense signal on T2 fluidattenuated inversion recovery or T2∗images. They occur up to 2 months before focal enhancement within the parenchyma in 10% of cases. Conclusions: In some lesions, the abrupt opening of the blood-brain barrier, detected by contrast enhancement on MRI, can have directly visible antecedent MRI changes centered on the central vein. We propose that these findings might be the basis for prior reports of subtle pre-parenchymal enhancement changes in quantitative MRI indices. In line with the venulocentric model of lesion development, our findings are consistent with the centrality of early perivenular events in lesion formation in vivo.