Feasibility of a transurethral ultrasound applicator for coagulation in prostate.

Transurethral resection of the prostate (TURP) is the surgical method routinely used in clinics to treat benign prostate hyperplasia (BPH). The purpose of this work is to demonstrate the feasibility of a transurethral ultrasound (US) applicator based on a miniature US flat transducer to coagulate prostatic tissues. Rabbit liver was found to comply well with human prostate. A significant fall in Doppler signal amplitude immediately after treatment demonstrated the applicator's ability to achieve haemostasis. The therapeutic depth extended from 6 to 10 mm, depending on conditions of exposure, and the coagulation rate ranged between 51% and 99%. The coagulated zone pinpointed on histological examination could be easily correlated to a permanent hypoechoic zone observed on B-scans of treated zones. This observation is most likely due to temperature-related changes in the acoustic attenuation of liver and, unfortunately, may not be visible in the prostate.