Magnetization transfer imaging of acute black holes in patients on glatiramer acetate

The aim of this study was to determine evolution of T1 unenhanced hypointense lesions (acute or chronic black holes (ABHs, CBHs)) by measuring their magnetization transfer ratio (MTR) changes over 12 months. 40 glatiramer acetate (GA)-naive patients with relapsing-remitting MS who presented with 1 or more contrast-enhancing lesions (CELs) at baseline underwent 1.5-T MRI at baseline and after 12 months. Lesions were classified into 4 patterns based on differences in lesion isointensity or hypointensity over 12 months. Of 115 CELs detected at baseline, 64, after 12 months, followed pattern A (isointense-isointense), 6 pattern B (isointense-hypointense), 33 pattern C (hypointense-isointense), and 12 pattern D (hypointense-hypointense). MTR significantly increased for all unenhanced T1 hypointense lesions (p = 0.02). Highest MTR increases were observed for patterns C (ABHs +18.2 %, p less than 0.001) and D (CBHs +34.2 %, p = 0.023), but significant improvement was also detected for pattern A (+1.4 %, p = 0.046); no significant MTR changes were found for pattern B. GA treatment significantly recovered MTR in ABHs and CBHs, possibly indicating a greater potential for remyelination.