Diffusion tensor subspace imaging (DiTSI) delineates small fibers and gray matter microstructure invisible to single-encoding techniques

Double diffusion encoding (DDE) MRI provides unique sensitization to microscale anisotropy although scalar representation of DDE data is challenging. The diffusion tensor subspace imaging (DiTSI) framework generates metrics from DDE images. In this study, post-mortem human brain tissue specimens were imaged and comparative analysis found that DiTSI but not DTI was able to provide distinct contrast in gray matter regions and at the gray/white interface. Additionally, small cranial nerve fibers of the brain stem were detectable using DiTSI, but not DTI or NODDI approaches and also showed remarkable abnormalities in Alzheimer’s disease tissue that were absent for DTI.