Spatial Resolution Requirements for Diffusion Tensor Imaging of Fornix

Ken E. Sakaie¹, Mark J. Lowe¹, Katherine Koenig¹, Robert A. Bermel², Lael Stone², Michael Phillips¹

As the primary efferent of hippocampus, diffusion tensor imaging (DTI) of fornix has potential as a biomarker for memory-related cognitive decline. As commonly-used spatial resolution for DTI risks partial volume averaging with surrounding CSF spaces, increases in diffusivity associated with disease that simply result from atrophy may be misinterpreted as change in tissue integrity. Here, we examine the use of high spatial resolution DTI of fornix to avoid partial volume averaging. The results suggest that 1mm isotropic voxels are sufficient for characterizing fornix in healthy controls but may be inadequate in multiple sclerosis patients experiencing atrophy.