Quantitative water content mapping in situ by in situ MRI: a promising forensic tool for post-mortem edema characterization

Motivation: Detection of brain edema at forensic examination remains subjective and observer dependent, but more objective criteria perform poorly. A notable exception is the normalized brain weight. Goal(s): Investigate MRI measures of death-associated edema. Approach: We establish in situ water content mapping and T2* relaxometry in a pilot study, adapting a fast quantitative protocol (~6min) using a standard mGRE sequence. Results: Using the derived quantitative maps, we find correlations between water content and T2* in WM, between tissue water weight and brain weight, and macromolecular density vs normalized brain weight. Microstructural characterization of brain oedema with qMRI seems feasible. Impact: Assessing the presence of edema as indicative of the cause of death is important for forensic examinations but is currently observer dependent. We seek to establish objective qMRI-based diagnostic measures and propose microstructural markers such as the macromolecular density.