Feasibility of using apparent thermophysical properties to incorporate the effect of blood perfusion in estimation of temperature in tissues

Estimation of temperature distribution in tissues and organs is critically important for treatments such as hyperthermia, radiofrequency ablation and cryosurgery which expose malignant tissue to extreme temperatures that are different from the physiological temperature. Commonly, the bioheat equation, instead of heat conduction equation, is used for estimation to incorporate the effect of blood perfusion, because the heat transfer in tissues is significantly affected by blood perfusion in addition to thermophysical properties of tissues. Nevertheless, in many cases, the rate of blood perfusion is not available for human tissues and organs. This study therefore aims to examine if we can use the normal heat conduction equation with apparent thermophysical properties to take the effect of blood perfusion into account. Feasibility was checked by comparing the results obtained from the heat conduction equation and the bioheat equation. The result indicated that the simulation with the apparent thermal conductivity or specific heat capacity does not agree well with the temperature distribution inside a tissue with blood perfusion. However, the apparent thermal conductivity was useful to estimate the size of growing ice ball produced during cryosurgery.