Sha Zhao1, Simon J. P. Meara2, Geoff J. M. Parker1,3
1ISBE, The University of Manchester, Manchester, England, United Kingdom; 2Physics Department, Clatterbridge Centre for Oncology, Merseyside, England, United Kingdom; 3Biomedical Imaging Institute, The University of Manchester, Manchester, England, United Kingdom
We propose a method for obtaining 3D proportional density maps for each major brain tissue component. Using double inversion recovery (DIR), we acquire images of grey matter, white matter, CSF and proton density. Each DIR image is divided by proton density, then an optimised correction factor is calculated for each so that the sum of these ratio images is unity for all voxels, thereby correcting for inter-tissue relaxation time, and coil sensitivity confounds. These proportional density images are potentially useful for studies of brain morphology and atrophy, as demonstrated in a cohort of healthy volunteers of different ages.