Proton magnetic resonance spectroscopic imaging reveals differences in spinocerebellar ataxia types 2 and 6

The objective of this study was to investigate cerebellar metabolism in pat ients with autosomal dominant cerebellar ataxia type 1 (ADCA-1) carrying tw o distinct mutations of spinocerebellar ataxia (SCA). Non-invasive image-gu ided proton magnetic resonance spectroscopy imaging (1H-MRSI) was performed in 4 patients with SCA2, and 3 patients carrying the SCAB mutation. For MR SI, we employed a spin-echo sequence (TR = 1500 msec, TE = 135 msec, slice thickness = 15 mm, FOV = 240 mm) and a stimulated-echo sequence (TR = 1500 msec, TE = 20 msec, slice thickness = 15 mm, FOV = 240 mm). Measures includ ed the peak Integral ratios of neuronal and glial markers [N-acetylaspartat e (NA) to creatine (Cr), choline-containing compounds (CHO) to Cr, and lact ate (LAC) to Cr]. We found NA:Cr ratios were significantly lower in patient s with SCA2 (40.4% lower) compared to patients carrying the SCA6 mutation. CHO:Cr ratios differed between the two mutations using short echo time (30. 8% lower in SCA2), but not when applying long echo time 1H-MRSI. Measuremen ts using long echo time revealed LAC peaks in all SCA2 patients. 1H-MRSI re vealed metabolic differences between SCA2 and SCA6 patients. NA:Cr ratios w ere significantly lower in patients with the SCA2 mutation compared to the SCA6 mutation, and LAC signals were obtained in the cerebella of SCA2 patie nts. In addition, CHO:Cr ratios showed different behavior using short and l ong TE, indicating differences in relaxation times of choline compounds in SCA2. (C) 2001 Wiley-Liss, Inc.