Magnetic resonance spectroscopy of the cervical cord in amyotrophic lateral sclerosis

The objective of this study was to use magnetic resonance spectroscopy (MRS) to compare metabolite ratios in the cervical spinal cord of ALS patients to healthy controls. Fourteen ALS patients and 16 controls were scanned using a 3T scanner. A rectangular voxel (8 X 5 X 35 mm) was placed along the main axis of the cord with the lower limit at the inferior aspect of the C2 vertebral body. MRS was performed with a point-resolved spectroscopy (PRESS) sequence. Water signals were suppressed using a three-pulse chemical shift selective (CHESS) saturation sequence. Relative concentrations of choline (Cho), creatine (Cr), myo-inositol (Myo), and NAA were computed from metabolite peaks. Differences in metabolite ratios between ALS patients and controls were assessed with a Wilcoxon rank-sum test. The relationship of metabolite ratios to clinical measures (ALSFRS-R and FVC) was determined by Pearson correlation. The NAA/Cr and NAA/Myo ratios were reduced by 40% and 38%, respectively, in ALS patients. The reduction in NAA/Myo and NAA/Cho correlated significantly with FVC, with correlation coefficients of 0.66 and 0.60, respectively. In conclusion, MR spectra can reliably be obtained from the cervical spinal cord in ALS. MRS of the cervical cord may be a useful biomarker of disease progression.