Prostatic tissue ablation by transrectal high intensity focused ultrasound: histological impact and clinical application.

In a phase-I clinical trial the morphologic impact and safety of high-intensity focused ultrasound (HIFU) administered transrectally for tissue ablation in human prostates (n = 54) was evaluated. Location and size of the tissue lesions correlated well with the predefined target area and revealed sharply delineated coagulative necrosis in all cases. Intervening tissues, such as the rectal wall and posterior prostate capsule were invariably intact. In a subsequent phase-II clinical trial safety and efficacy of transrectal HIFU as a novel minimally invasive treatment modality for patients with symptomatic benign prostatic hyperplasia (BPH; n = 102) was determined. The maximum urinary flow rate (Qmax, ml/s) increased from 9.1+/-4.0 to 12.9+/-6.1 (3 months, n=86), 12.7+/-5.1 (6 months, n=78) and 13.3+/-6.1 (12 months, n=56). In the same time period the post void residual volume (ml) decreased from 131+/-115 to 46+/-45, 57+/-46 and 48+/-36 and the AUA symptom score decreased from 24.5+/-4.7 to 13.3+/-4.4, 13.4+/-4.7 and 10.8+/-2.5. A subset of patients (n=30) underwent multichannel pressure flow studies, which demonstrated that transrectal HIFU reduces bladder outflow obstruction. These data demonstrate that transrectal HIFU is capable of inducing coagulative necrosis in the human prostate via a transrectal approach while preserving intervening and adjacent tissue. A 48% improvement of uroflow and a 53% decrease of urinary symptoms 1 year after treatment prove that transrectal HIFU is an effective and safe minimally invasive treatment option for BPH.