High spatial and angular resolution diffusion-weighted imaging reveals forniceal damage related to memory impairment.

INTRODUCTION: Diffusion tensor imaging (DTI) measures in patients with multiple sclerosis (MS), particularly those measures associated with a specific white matter pathway, have consistently shown correlations with function. This study sought to investigate correlations between DTI measures in the fornix and common cognitive deficits in MS patients, including episodic memory, working memory and attention. MATERIALS AND METHODS: Patients with MS and group age- and sex-matched controls underwent high-resolution diffusion scanning (1-mm isotropic voxels) and cognitive testing. Manually drawn forniceal regions of interest were applied to individual maps of tensor-derived measures, and mean values of transverse diffusivity (TD), mean diffusivity (MD), longitudinal diffusivity (LD) and fractional anisotropy (FA) were calculated. RESULTS: In 40 patients with MS [mean age ± S.D.=42.55 ± 9.1 years; Expanded Disability Status Scale (EDSS)=2.0 ± 1.2; Multiple Sclerosis Functional Composite (MSFC) score=0.38 ± 0.46] and 20 healthy controls (mean age ± S.D.=41.35 ± 9.7 years; EDSS=0.0 ± 0; MSFC score=0.74 ± 0.24), we found that FA, MD and TD values in the fornix were significantly different between groups (P<.03), and patient performance on the Brief Visuospatial Memory Test-Revised (BVMT-R) was correlated with DTI measures (P<.03). DISCUSSION: These results are consistent with findings of axonal degeneration in MS and support the use of DTI as an indicator of disease progression.