Estimation of tissue properties in post-mortem brains to time from death using magnetic resonance elastography

Authors

• J Mojumder
• YC Lu
• AM Diano
• A Alshareef
• AK Knutsen
• M McGarry
• CL Johnson
• JA Butman
• DL Pham

Abstract

Traumatic brain injury (TBI), a serious health condition, can cause neurological dysfunction to varying degrees depending on the nature of the mechanical insult. Biomechanical TBI studies under high loading conditions require postmortem head-surrogates (PMHS) as ethical concerns prohibit such experiments in living human subjects; thus, it is important to understand the relationship between the mechanical properties of PMHS brain tissue and living tissue. In this study, we performed magnetic resonance elastography (MRE) on three PMHS specimens to estimate the material properties of the cadaveric brain. During the MRE experiment, the specimens were placed on a soft “pillow” driver attached to a pneumatic actuator system that applied an excitation in the anterior-posterior (AP) direction. Using a single-shot echoplanar imaging (EPI) sequence, MRE displacement data were acquired at 50 Hz, with an isotropic imaging resolution of 2.5 mm. Using a non-linear inversion algorithm, brain tissue material properties, namely, the stiffness and the damping ratio were estimated. Compared to prior studies on in vivo human data, significant increases in average stiffness were found in PMHS 2 and 1 (~250% and 128%, respectively) in PMHS 1 compared to the in vivo subjects (p-value<0.05), whereas, significant decreases in average damping ratio PMHS 2, 1, and 3 (~66%, ~59%, and ~50%). Differences may be attributed to freshness of the specimen, which ranged from 48 to 72 hours, and donor demographics. These measurements can be used to understand the relationship between in vivo and post-mortem data for building improved computational models of TBI.

Scientific Focus Area: Biomedical Engineering and Biophysics

This page was last updated on Tuesday, August 6, 2024