6G-6 Local Nonlinear Arterial Elastic Modulus Reconstruction From In Vivo Strain Imaging and PWV

An optimized elastic modulus reconstruction procedure from ultrasound strain and pulse wave velocity (PWV) measurements was validated using a commercial ultrasound scanner. Longitudinal and transverse scans were performed on a vessel phantom connected to a pulsatile pump. Time delay between the ultrasound beams at each side of the transducer determines PWV and transverse elasticity imaging estimates intramural strain. Elastic modulus was reconstructed combining these two independent measurements. The reconstructed modulus compared well to direct mechanical measurements within 10 % error. To assess clinical feasibility, an in vivo free-hand ultrasound scanning procedure was performed on a local vein graft at anastomosis of a recruited subject under IRB approval. Transverse and longitudinal scanning was performed on the vein side of the anastomosis while compressing to a pressure equaling diastolic pressure. By equalizing the internal arterial baseline pressure in this way, significant strains were achieved. Elastic moduli with and without compression were fit to a pure exponential function describing the nonlinear elasticity of the arterial wall. With only two measurement points at different intraluminal pressures, the vein elastic property was fully characterized demonstrating the feasibility of determining the un-distended elastic modulus in vivo