Numerical Simulation of Effects of Bioheat Transfer Characteristics of Malignant Melanoma on Thermal Conductivity Measurements.

In our previous study, we successfully detected a difference in the effective thermal conductivity between an invasive melanoma lesion and healthy skin, through clinical experiments conducted on melanoma patients. We found that the effective thermal conductivity of the lesions correlated with the tumor thickness, suggesting that it may be correlated with the prognostic risk of melanoma. However, the bioheat transfer mechanisms of the correlation remained unknown. The aim of this study was to numerically investigate the effects of the bioheat transfer characteristics of malignant melanoma on thermal conductivity measurements and explore the cause of the difference in the effective thermal conductivity between lesions and healthy skin. We used two different bioheat transfer models, the Pennes model and local thermal nonequilibrium model, and investigated the cause of the aforementioned differences by varying the bioheat transfer parameters associated with the thermophysical properties and blood flow of a tumor. The calculation results indicated that the contribution of the blood flow can be dominant in a measurement comprising the use of a guard-heated thermistor probe. Therefore, we found that it is necessary to take into consideration the contribution of the convective term to the effective thermal conductivity of the lesion in order to explain the clinical data of a Stage IV invasive melanoma.