Simultaneous measurements of local tissue temperature and blood perfusion rate in the canine prostate during radio frequency thermal therapy

Abstract

Local tissue temperature and blood perfusion rate were measured simultaneously to study thermoregulation in the canine prostate during transurethral radio-frequency (RF) thermal therapy. Thermistor bead microprobes measured interstitial temperatures and a thermal clearance method measured the prostatic blood perfusion rate under both normal and hyperthermic conditions. Increase in local tissue temperature induced by the RF heating increased blood perfusion throughout the entirety of most prostates. The onset of the initial increase in blood perfusion was sometimes triggered by a temporal temperature gradient at low tissue temperatures. When tissue temperature was higher than 41 degrees C, however, the magnitude and the spatial gradient of temperature may play significant roles. It was found that the temperature elevation in response to the RF heating was closely coupled with local blood flow. The resulting decrease in or stabilization of tissue temperature suggested that blood flow might act as a negative feedback of tissue temperature in a closed control system. Results from this experiment provide insights into the regulation of local perfusion under hyperthermia. The information is important for accurate predictions of temperature during transurethral RF thermal therapy.