In vivo measurement of intrinsic thermal conductivity of living blood-perfused tissue

Understanding the intrinsic thermal transport behavior of living blood-perfused tissue is essential in applications that require predicting the correct thermoregulation behavior of humans, discovering the location of abnormal tissues, and treating cancer through hyperthermia or thermal ablation. In this study, we employ an in vivo measurement technique that genuinely measures the intrinsic tissue thermal conductivity and blood perfusion rate as a function of tissue temperature. The emphasis is on "in vivo" measurement because physiological differences across individuals must be considered (e.g., water content within the tissue). Tissue temperatures from 30.5 degrees C to 35.5 degrees C yielded average intrinsic thermal conductivity values of 0.33 +/- 0.04 W/m-K in three subjects. This value agrees well with that of excised human epidermis (0.21-0.41 W/m-K). The blood perfusion rate inevitably increased from 1.43 x 10-4 to 3.42 x 10-3 m3/s/m3 with increasing tissue temperature consequently from vasomotion. The findings suggest that the proposed approach can serve as a noninvasive, real-time, personalized, and in vivo method for determining the intrinsic thermal behavior of living blood-perfused tissue. Such a methodology also has the potential to revolutionize fields that deal with tumor modeling, treatment, and thermal comfort optimization, ultimately benefiting human health and well-being.