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 patients with autosomal dominant cerebellar ataxia type 1 (ADCA‐I) carrying two distinct mutations of spinocerebellar ataxia (SCA). Non‐invasive image‐guided proton magnetic resonance spectroscopy imaging (1H‐MRSI) was performed in 4 patients with SCA2, and 3 patients carrying the SCA6 mutation. For MRSI, 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 included the peak integral ratios of neuronal and glial markers [N‐acetylaspartate (NA) to creatine (Cr), choline‐containing compounds (CHO) to Cr, and lactate (LAC) to Cr]. We found NA:Cr ratios were significantly lower in patients 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. Measurements using long echo time revealed LAC peaks in all SCA2 patients. 1H‐MRSI revealed metabolic differences between SCA2 and SCA6 patients. NA:Cr ratios were significantly lower in patients with the SCA2 mutation compared to the SCA6 mutation, and LAC signals were obtained in the cerebella of SCA2 patients. In addition, CHO:Cr ratios showed different behavior using short and long TE, indicating differences in relaxation times of choline compounds in SCA2. J. Magn. Reson. Imaging 2001;13:553–559. © 2001 Wiley‐Liss, Inc.