Characterising the temporal evolution of fixation in human post mortem brain via linear relaxometry modelling – a marker of cross-linking?

MRI-based biophysical models are typically validated by comparison to ex-vivo histology of fixed tissue. The fixation process itself and the accompanied autolysis processes strongly modify tissue composition, and lead to MR signal changes, making the validation of biophysical models for in vivo MRI particularly challenging. To better understand the temporal evolution of the fixation process within the whole brain and its influence on MRI parameters, we monitor the temporal evolution of the fixation process of a whole human post-mortem brain using the linear relaxometry model across 15 time-points comprised of one unfixed, in-situ MRI scan and 14 ex-vivo MRI scans at different stages of the fixation process (days 1-93)