Surgeon assessment versus laboratory measurement: brain tissue mechanics quantified by expert opinion

Abstract

Transcranial ultrasound (tUS) is a plausible means of measuring motion of the brain due to traumatic force or structural abnormalities. However, limited data in the literature on the mechanical properties of human brain tissue make it practically impossible to develop a mechanically realistic ultrasound phantom that can mimic the brain under these conditions. The present study aimed to determine, by indirect qualitative assessment, the stiffness of in-vivo brain tissue. Six surgeon examiners under blinded conditions physically examined 16 gelatin-based tissue phantoms (0.020-0.095 g/mL) to determine which sample best matched the stiffness of brain tissue in-vivo. Ten cylindrical phantom samples, acoustically matched to human brain tissue, were prepared based on the examiners’ responses (0.030±0.008 g/mL), and stress-strain behavior was characterized under compression up to 50% strain. The average compressive stress at 50% strain was 10.3±1.4 kPa. These results correlate well with those previously reported in the literature, and add a practical measure of brain stiffness to the paucity of information available on human brain tissue mechanics. Furthermore, it is potentially an initial step in developing mechanically realistic models of structural disorders of the brain and traumatic brain injury to evaluate theories on the brain’s mechanical behavior under these circumstances.