Diffusion tensor imaging of the cervical spinal cord of patients with Neuromyelitis Optica

Abstract

BackgroundPrevious studies have demonstrated a correlation between Expanded Disability Status Scale (EDSS) and Diffusion Tensor Imaging (DTI) metrics, but the conclusions were based on evaluations of the entire cervical spinal cord. ObjectivesThe purpose of this study was to quantify the FA and MD values in the spinal cord of NMO patients, separating the lesion sites from the preserved sites, which has not been previously preformed. In addition, we attempted to identify a correlation with EDSS. MethodsDTI was performed in 11 NMO patients and 11 healthy individuals using a 1.5-T MRI scanner. We measured the FA and MD at ROIs positioned along the cervical spinal cord. The mean values of FA and MD at lesion, preserved and spinal cord sites were compared with those of a control group. We tested the correlations between the mean FA and MD with EDSS. ResultsFA in NMO patients was significantly reduced in lesion sites (0.44 vs. 0.55, p=0.0046), preserved sites (0.46 vs. 0.55, p=0.0015), and all sites (0.45 vs 0.55, p=0.0013) while MD increased only in lesion sites (1.03×10−3mm2/s vs. 0.90×10−3mm2/s, p=0.009). The FA demonstrated the best correlation with EDSS (r=−0.7603, p=0.0086), particularly at lesion sites. ConclusionsThe results reinforce the importance of the FA index and confirm the hypothesis that NMO is a diffuse disease.