DESCRIPTION: A new approach to studying thermo-regulation in the prostate during hyperthermia will be developed which will attempt for the first time to measure and model several key aspects of microvascular flow on local tissue heat transfer. In particular their specific aims are to 1) examine blood perfusion rates within the canine prostate using a thermal clearance method - Thermal Pulse Decay (TPD). Thermal pulses will be delivered to the prostatic tissue and temperature decays in the tissue be measured subsequently by thermistor bead probes (0.3mm dia.) Local blood perfusion rates will be determined by fitting the actual temperature measurements to predictions from the bioheat transfer model; 2) study the microvascular architecture in the canine prostate using computer visualization. A series of vascular branch images on contiguous slices obtained from the plastic filled canine prostatic vascular casts will be viewed under an optical microscope and recorded onto a disk. Three dimensional structures of these vascular branches will be reconstructed by imputing these images and processing them in a visualization environment. Having the three dimensional image will allow them to clearly observe and accurately measure vascular branching angles and diameters within the structure; 3) develop a three dimensional heat transfer model to predict temperature distributions in the canine prostate during the transurethral microwave hyperthermia. This model will be built based on the quantitative vasculature information and local blood perfusion rates to account for the thermal contribution from the flowing blood. The validity of the model will be examined by performing temperature mapping in the in vivo canine prostate during the transurethral microwave hyperthermia; 4) perform parametric studies using the new heat transfer model developed in aim 3. The effect of microwave power, the temperature of cooling water between the microwave antenna and the urethral wall, and local blood perfusion rate on the tissue temperature rise during hyperthermia will be examined. Successful completion of this proposed research will lay an important foundation for future study in hyperthermia treatment of Benign Prostatic Hyperplasia (BPH), a common problem among elderly men.