Combined 3T diffusion tensor tractography and 1H-MR spectroscopy in motor neuron disease.

BACKGROUND AND PURPOSE: Diagnostic confidence in motor neuron disease may be improved by the use of advanced MR imaging techniques. Our aim was to assess the accuracy (sensitivity/specificity) and agreement of combined (1)H-MR spectroscopy (proton MR spectroscopy) and diffusion tensor imaging (DTI) at 3T in patients with suspected motor neuron disease regarding detection of upper motor neuron (UMN) dysfunction. MATERIALS AND METHODS: Eighteen patients with suspected motor neuron disease were studied with MR spectroscopy/DTI and clinically rated according to the El-Escorial and ALSFRS-R scales. For MR spectroscopy, absolute N-acetylaspartate (NAA), choline (Cho), and phosphocreatine (PCr) concentrations and relative NAA/Cho and NAA/PCr ratios of corresponding volumes of interest within the primary motor cortex were calculated. For DTI, fractional anisotropy (FA) and mean diffusivity (MD) were measured bilaterally at the level of the precentral gyrus, corona radiata, internal capsule, cerebral peduncles, pons, and pyramid. FA and MD statistics were averaged on the corticospinal tracts (CSTs) as a whole to account for a region-independent analysis. RESULTS: MR spectroscopy indicated NAA reduction beyond the double SD of controls in 6 of 8 patients with clinical evidence for UMN involvement. Congruently, the mean FA of these patients was significantly lower in the upper 3 regions of measurements (P < .01). Overall, MR spectroscopy and DTI were concordant in all except 3 cases: 1 was correctly excluded from motor neuron disease by DTI (genetically proved Kennedy syndrome), whereas MR spectroscopy indicated CST involvement. MR spectroscopy and DTI each were false-positive for CST affection in 1 patient with lower motor neuron involvement only. CONCLUSION: Combined MR spectroscopy/DTI at 3T effectively adds to the detection of motor neuron disease with a high degree of accordance.

Voxel-based morphometry and voxel-based relaxometry in multiple system atrophy-a comparison between clinical subtypes and correlations with clinical parameters.

Multiple system atrophy (MSA) is a neurodegenerative disease affecting basal ganglia, brainstem, cerebellum, and intermediolateral cell columns of the spinal cord. Clinically, a cerebellar (MSA-C) and a parkinsonian variant of MSA (MSA-P) are distinguished. We used voxel-based morphometry (VBM) and voxel-based relaxometry (VBR) in 48 MSA patients (32 MSA-C, 16 MSA-P) and 46 controls. In MSA-C, VBM revealed gray matter loss in cerebellum, right thalamus, both putamina and several cortical regions including insular cortex. Gray matter loss in the cerebellum and insular cortex was correlated with disease duration and severity. There was white matter loss in the brainstem, which was correlated with disease duration and severity. VBR analysis in MSA-C showed decreased relaxation rate R2 in cerebellum, pontine brainstem and cortical regions including insular cortex. In MSA-P, gray matter was reduced in cerebellum, dorsal midbrain, both putamina, and several cortical regions including insular cortex. A correlation with disease duration and severity was detected only for some small cortical areas. Direct comparison of MSA-C and MSA-P showed differences only in infratentorial brain regions where structural abnormalities were more pronounced in MSA-C than in MSA-P. In MSA-C, there was a stronger reduction of gray matter in the basal parts of the cerebellum, of white matter in the brainstem and of the relaxation rate R2 in the cerebellum and brainstem.