Interstitial temperature mapping during Prolieve transurethral microwave treatment: imaging reveals thermotherapy temperatures resulting in tissue necrosis and patent prostatic urethra.
OBJECTIVE
Temperature mapping of the prostate during transurethral microwave thermotherapy and imaging of the resultant zones of tissue necrosis have been previously performed using several commercial systems. This study was performed using the Prolieve Thermodilatation System, which simultaneously compresses the prostate with a 46F balloon circulating heated fluid and delivering microwave energy into the prostate.


METHODS
Interstitial temperature mapping during Prolieve treatment was performed on 10 patients with benign prostatic hyperplasia using 24 temperature sensors arrayed throughout the prostate. Voiding cystourethrograms were performed on 3 additional patients treated without temperature mapping to document the patency of the prostatic urethra 1 hour after treatment. Gadolinium-enhanced magnetic resonance imaging studies were performed on all patients 1 week after treatment to determine the extent and pattern of tissue necrosis resulting from transurethral microwave thermotherapy.


RESULTS
Interstitial temperature mapping found that the heating pattern generated by the Prolieve system created average peak temperatures of 51.8 degrees C an average of 7 mm away from the prostatic urethra. These temperatures were greater near the bladder neck and mid-gland than toward the prostatic apex. Subtherapeutic temperatures were seen adjacent to the urethra, consistent with the viable tissue seen on gadolinium-enhanced magnetic resonance imaging sequences. Magnetic resonance imaging also revealed necrotic zones that were consistent with sustained temperatures greater than 45 degrees C. Voiding cystourethrograms showed widely patent prostatic urethras 1 hour after treatment.


CONCLUSIONS
Transurethral microwave thermotherapy with the Prolieve Thermodilatation System produced sustained therapeutic temperatures that resulted in tissue necrosis while maintaining viable tissue surrounding a temporarily dilated prostatic urethra.
Larson
Benjamin T
BT
Institute of Medical Research, Scottsdale, Arizona 85260, USA.
Robertson
David W
DW
Huidobro
Christian
C
Acevedo
Cristian
C
Busel
David
D
Collins
Joseph
J
Larson
Thayne R
TR
D001831:Body Temperature / Q000502:physiology*; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D016343:Monitoring, Intraoperative / Q000379:methods*; D009336:Necrosis / Q000473:pathology; D011470:Prostatic Hyperplasia / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D020728:Transurethral Resection of Prostate / Q000295:instrumentation*; D016896:Treatment Outcome; D014521:Urethra / Q000000981:diagnostic imaging / Q000503:physiopathology*; D014563:Urodynamics; D014567:Urography