Kunio Odajima

New technique for prostatectomy using Ho:YAG laser

To develop a new transperineal laser prostatectomy through a biopsy needle, we determined the efficiency of a pulsed Nd:YAG laser irradiation for canine prostate. The Ho:YAG laser ((lambda) equals 2.1 micrometers ) may induced stress-wave to destroy the small vessels in prostate. After the exposure of the canine prostate, it was punctured by the needle. A quartz fiber of which core-diameter was 200 or 400 micrometers was inserted into the 18 G needle. The irradiation fluence was set to 150 - 600 J/cm2 and repetition rate was kept at 2 Hz. The cross-section of the irradiated portion of the prostate extracted immediately after the irradiation showed dark-colored hemorrhage layer around the ablation tract with 1 - 2 mm thickness. Some hemorrhage was histologically seen in stoma and gland in the irradiated prostate. In the case of 150 - 175 J/cm2 in the irradiation fluence, the irradiated portion of the prostate was found in the wedge-shaped area with brown color at one week after the irradiation. The lymphocytes infiltrating into the wedge-shaped zone were found. The wedge- shaped zone spread over the prostate and the change of urethral mucosa was minimum at one month after the irradiation. In the case of 500 - 600 J/cm2 irradiation, the paraurethral cavity was made at one month after the irradiation. The histological examination showed that the hemorrhage and subsequent histological changes may be caused by the laser induced stress-wave rather than thermal effect. Our results suggest that transperineal irradiation of pulsed Ho:YAG might offer an effective treatment for benign prostatic hyperplasia with the minimal damage to the urethral mucosa.