Diffusion tensor imaging (DTI) of the cervical cord in sensory ganglionopathies

Abstract

The Sensory Ganglionopathies (SG) are a rare, yet distinct subgroup of peripheral neuropathies characterized by selective damage to the cell bodies of sensory neurons in the dorsal root ganglia of the spinal cord. This ultimately leads to degeneration of its projections, both central and peripheral. The diagnosis of SG is often challenging and basically relies upon nerve conduction studies (NCS). T2 weighted images of the spinal cord are able to show dorsal column abnormalities in SG, but this is not a sensitive finding in the early stages of the disease. Diffusion Tensor Imaging (DTI) is a novel MRI technique that identifies microstructural abnormalities in white matter tracts much earlier than conventional MRI sequences. In this scenario, our objective is to determine the usefulness of DTI of the spinal cord as a diagnostic tool for patients with SG. Methods: We will enroll 40 subjects in the study, 20 of which having SG and the other 20 healthy controls matched for age and gender. The patients will be submitted to clinical and neurological evaluation in the same day of MRI scans acquisition. Disease severity will be quantified with the Scale of Assessment and Rating of Ataxia (SARA). MRI scans will be performed in a 3T Philips device. For each subject, two sets of images will be recorded: T2 weighted and DTI, both acquired in the axial plane. Circular ROIs will be drawn in the posterior region of the spinal cord at the C2-C3 transition, so that Fractional Anisotropy (FA) and Mean Diffusivity (MD) can be calculated in the dorsal columns. Non-parametric tests will be employed to compare groups and Spearman coefficient to estimate the correlation between DTI metrics and clinical data. We believe that our results can show that spinal cord DTI is a useful diagnostic and prognostic test for SG patients. (AU)