Dynamics of laser induced thermoelastic expansion of native and coagulated ex-vivo soft tissue samples and their optical and thermo-mechanical properties

The interferometric measurement of laser induced thermoelastic expansion of tissue samples can be used to estimate their optical, thermal and mechanical properties. This method was used to assess the Gruneisen coefficient and optical attenuation depth for native and coagulated ex-vivo bovine liver and porcine kidney samples. The results demonstrate decreases of 54% and 60% in the optical attenuation depth in bovine liver and porcine kidney after coagulation, respectively. The Gruneisen coefficient of native porcine kidney was determined to be 58% smaller (p < 0.05) that native bovine liver. The measured Gruneisen coefficients for native and coagulated ex-vivo porcine kidney were 0.07 ± 0.03 and 0.105 ± 0.02, respectively, whereas the Gruneisen coefficients for native and coagulated liver were 0.126 ± 0.036 and 0.127 ± 0.04, respectively. Our measurements indicate significant inter sample variability due likely to inherent variations in tissue optical absorption and surface preparation.