Effect of blood flow and metabolism on multidimensional heat transfer during cryosurgery.

Cryosurgery has been recently accepted as a treatment option for eradicating undesirable tissues, especially tumor tissues, due to its minimally invasive nature and low hospitalization needs. A multidimensional, finite element analysis (FEA) for the cooling, holding and rewarming processes of biological tissues during cryosurgery is presented. The tissues were treated as non-ideal materials with temperature dependent thermophysical properties. The enthalpy method has been applied to solve the non-linear problem. The influence of heating effect due to blood flow and metabolism was studied, and furthermore, the effect of pre-injecting solutions with particular thermal properties into the target tissues was also numerically studied. It was found that the heat source term due to blood flow and metabolism in the bioheat transfer equation has a significant influence on the thermal and thermal gradient histories of the target tissues, and that the method of injection of solutions with particular thermal properties into the target tissues before cryosurgery may be a possible way to optimize the treatment process. However, in vitro experiments have not fully supported this viewpoint.