Multiple Sclerosis: Hyperintense Dentate Nucleus on Unenhanced T1-weighted MR Images Is Associated with the Secondary Progressive Subtype

Purpose: To describe the occurrence of abnormal hyperintensity in the dentate nucleus on T1-weighted magnetic resonance (MR) images in patients with multiple sclerosis (MS) as a neuroradiologic sign of gray matter involvement. Presence of the finding was evaluated for association with disability, clinical MS subtype, total lesion volume on T1- and T2-weighted MR images (lesion load), and brain atrophy. Materials and Methods: Written informed consent was waived by the Ethics Committee because of the retrospective nature of this single-center Institutional Review Board - approved study. MR examinations of 185 patients with MS were reviewed, and 119 patients were included for analysis. Two neuroimagers, who were blinded to clinical data, assessed the presence of a hyperintense dentate nucleus on T1- weighted MR images. The presence of this radiologic alteration was then evaluated in relation to MS subtype, clinical disability, T1 and T2 lesion load, and whole-brain atrophy measurements. Fisher exact, chi(2), and Mann-Whitney U tests were used to evaluate differences in clinical and imaging features between patients with and those without a T1 hyperintense dentate nucleus. Results: Twenty-three (19.3%) of the 119 patients had a hyperintense dentate nucleus on unenhanced T1- weighted MR images. This finding was related to the secondary progressive subtype of the disease, a higher score on the Expanded Disability Status Scale, a higher brain lesion load, and tissue loss. None of the patients with primary progressive MS had a hypterintense dentate nucleus. Conclusion: Hyperintensity of the dentate nucleus may be present on unenhanced T1- weighted MR images of patients with MS and is associated with the secondary progressive disease subtype and with increased clinical disability, lesion load, and brain atrophy.