INCREASED PROSTATIC BLOOD-FLOW IN RESPONSE TO MICROWAVE THERMAL-TREATMENT - PRELIMINARY FINDINGS IN 2 PATIENTS WITH BENIGN PROSTATIC HYPERPLASIA

Objectives. To determine the effects on prostate blood flow of heat ge nerated by microwave thermal treatment in patients with benign prostat ic hyperplasia. Methods. Prostate blood flow was evaluated by continuo us transrectal color Doppler ultrasonography in 2 patients at baseline , after implantation of interstitial needles used for thermal mapping, and during microwave thermal treatment. Temperatures at 30 prostatic, periprostatic, urethral, and rectal sites were continuously monitored , In 1 patient, transrectal prostate compression was applied and the b lood flow and temperature response to this maneuver noted. Results. Mi crowave thermal treatment achieved maximum prostate temperatures of 59 degrees C at 5 mm radially from the urethra, Urethral and rectal temp eratures remained low. Marked increases occurred in prostate blood flo w in response to microwave thermal treatment. These increases were app arent throughout the prostate gland, with the greatest increase in per fusion occurring in the peripheral zone and the posterior half of the transitional zone. After 15 minutes of microwave treatment, peak systo lic blood flow increased 99% and 70% in patients 1 and 2, respectively , while end-diastolic blood flow climbed 50% and 112%, respectively. P rostate compression resulted in a prompt quenching of;blood flow and a n increase in prostate temperature. Conclusions. Based on these prelim inary findings in 2 patients, prostate blood flow increases markedly i n response to microwave thermal treatment. This compensatory increase in blood flow is likely to be a significant treatment-limiting factor in achieving effective thermoablation.