Experimental study on the effect of high-intensity focused ultrasound (HIFU) using Sonablate-500 in the ablation of canine prostate.

To investigate the safety, feasibility and effectiveness of transrectal high-intensity focused ultrasound (HIFU) in the ablation of canine prostate, 20 dogs were divided randomly into 5 groups. Sixteen canine prostates were treated with the third-generation transrectal HIFU device (Sonablate-500). Transrectal ultrasound images of the prostate and prostatic urethra were observed preoperatively and postoperatively. Serial study was performed 30 min, 30 days, 60 days and 180 days after the therapy. The rectum, periprostatic tissues, and prostate were excised en bloc and the tissues were fixed for gross and histological analysis. Our results showed that the average maximal diameter of prostatic urethra was 0.59+/-0.11 cm before the operation and 2.57+/-0.98 cm 60 days after the operation. The volume of prostate was 6.5+/-3.12 cm(3) before the treatment while the volume was 4.13+/-0.23 cm(3) 60 days after the treatment and the differences were statistically significant (P<0.05). Histologically, there was a clear demarcation between the necrotic area of the treated tissues and the unaffected surrounding tissues. All the necrotic tissues in the targeted zone broke off and the prostatic urethra became cavitary 60 days later. The more frequent complications were urinary retention and frequency and hematuria. No rectal injury occurred during the treatment. It is concluded that the third-generation transrectal HIFU is capable of destroying prostatic tissue, substantially increasing the width of the prostatic urethra without causing injury to the adjacent tissues. The risk of postoperative complications associated with HIFU was low. HIFU may become a safe, effective and minimally invasive alternative for the treatment of prostatic diseases.