David Raffelt1, 2, J-Donald Tournier1, 3, Stuart Crozier4, Kathryn A. Ellis5, Ralph Martins6, Victor L. Villemagne, 37, Colin L. Masters7, David Ames8, Christopher C. Rowe3, Olivier Salvado2, Alan Connelly1, 3
1Brain Research Institute, Florey Neuroscience Institutes, Melbourne, VIC, Australia; 2The Australian E-Health Research Centre, CSIRO, Brisbane, QLD, Australia; 3Department of Medicine, University of Melbourne, Melbourne, VIC, Australia; 4Biomedical Engineering, School of ITEE, University of Queensland, Brisbane, QLD, Australia; 5Department of Psychiatry, University of Melbourne, Melbourne, VIC; 6Edith Cowan University, Centre of Excellence for Alzheimers Disease Research & Care, Joondalup, WA, Australia; 7The Mental Health Research Institute, University of Melbourne, Melbourne, VIC, Australia; 8Department of Radiology, University of Melbourne, Melbourne, VIC, Australia
In this work, we investigate Alzheimers Disease (AD) using a recently developed method for voxel-based analysis (VBA) of diffusion-weighted MRI called Apparent Fibre Density (AFD). Unlike existing measures such as Fractional Anisotropy, AFD permits population differences to be localised in both the spatial and orientation domains. This enables pathology-induced changes to be attributed to a single fibre population in a region containing multiple fibres. Our findings demonstrate a significant decrease in AFD in AD patients compared to healthy subjects within voxels and orientations corresponding to the cingulum, corpus callosum, uncinate fasciculus, and superior longitudinal fasciculus and anterior commissure.