Noninvasive surgery of prostate tissue by high intensity focused ultrasound: an updated report.

OBJECTIVE: To establish clinical efficacy and safety of High Intensity Focused Ultrasound (HIFU) for the treatment of benign prostatic hyperplasia (BPH) in a multiple site clinical study. METHODS: Seven clinical sites were set up for the studies, five in the USA, one in Canada and one in Japan respectively. Sixty two patients were enrolled in these three studies. Transrectal ultrasound probes made to produce sufficient acoustic power required for focused ultrasound surgery of the prostate as well as to perform imaging of the prostate, were employed in the study. The probes ware made of 2.5, 3.0, 3.5, 4.0 and 4.5 cm focal length transducers to treat varying prostate sizes and shapes and operated at 4 MHz frequency for both imaging and treatment. The employed ultrasound device produced both transverse and longitudinal images of the prostate on the same display. The images were used for selection of tissue volume, treatment planning and monitoring of tissue during the HIFU treatment cycle. The patients in the USA and Canada were followed for two years and those in Japan were followed for one year on a regular interval. The results were evaluated for changes in the peak flow rate (Qmax in ml/s), quality of life (QOL) and International Prostate Symptom Score (IPSS). RESULTS: The average pre / post treatment results at 180 days were significantly different for Qmax, QOL and IPSS 8.5/14.2 (ml/s), 4.7/2.1 and 22/10 respectively. CONCLUSION: Under this protocol, HIFU was found safe and efficacious for the treatment of BPH. The HIFU treatment produced statistically significant results for the parameters measured with least complications. Additionally, the HIFU treatment was found to be durable.

Noninvasive ultrasonic subtotal ablation of the prostate in dogs.

OBJECTIVE: To determine whether high-intensity focused ultrasound (HIFU) can be used for subtotal ablation of the prostate gland in dogs without causing damage to surrounding tissues. DESIGN: Experimental trial. ANIMALS: Adult hounds > or = 5 years old and weighing between 20 and 30 kg. PROCEDURE: Prostatic ablation was performed in all dogs, using a transrectal HIFU probe. Acute effects of HIFU treatment were evaluated in 4 dogs. These dogs were euthanatized and necropsied 4 hours after the procedure. Chronic effects were evaluated in the other 3 dogs. Serial CBC, serum biochemical analyses, urinalyses, and transrectal ultrasonography were performed. Dogs were euthanatized and necropsied 3 months (1 dog) or 1 year (2 dogs) after HIFU treatment. RESULTS: Histologic examination of the prostate glands from the 4 dogs euthanatized 4 hours after treatment revealed that 80 to 90% of the gland had undergone hemorrhagic, liquefactive necrosis. Only slight discoloration of the prostatic capsule was detected, and there were not any gross or histologic lesions of the rectal mucosa or urinary bladder. All 3 dogs followed up after HIFU treatment developed cystic cavities within the prostate. Clinicopathologic testing did not indicate any long-term adverse effects. CONCLUSIONS AND CLINICAL RELEVANCE: This method was effective in causing subtotal ablation of prostatic tissue in dogs. Further study of morbidity is required before the technique can be used clinically.