Material characterization of in vivo and in vitro porcine brain using shear wave elasticity

Shear wave elasticity imaging was used to examine changes in porcine brain tissue shear modulus as a function of several experimental and physiological parameters. Animal studies were performed with two different ultrasound transducers. Four in vivo subjects were exposed to inversion and increased ICP, over a relevant physiological range (0–40mmHg), was correlated with shear wave speed estimates. Additional in vitro specimens were used to investigate presence of changes with temperature, confinement, spatial location, and transducer orientation. Statistically significant results include a 28% decrease in stiffness with increased temperature and a 22–50% increase in stiffness with decreasing external confinement.