MRI-correlated morphological changes after Nd:YAG laser treatment of the human prostate with the SideFocus fiber.

Abstract

Optimal treatment parameters and appropriate methods of examination for Nd:YAG laser coagulation of the human prostate in dependence of power-setting and time using the SideFocus side-firing delivery system have been determined. Transurethral free-beam laser coagulation was performed in 10 patients prior to planned radical prostatectomy or cystoprostatectomy. Thereof, 6 patients underwent transperitoneal laparoscopic lymphadenectomy and laser coagulation of the prostate between 4 and 9 days prior to open surgery. These same patients had undergone MRI examination with an endorectal coil during staging and prior to radical prostatectomy. Depth and volume of coagulated prostatic tissue of a 4-quadrant laser application were measured at power-settings of 40 W/90 s and 60 W/60 s. There was no difference in volume coagulation between the two treatment modalities. In contrast there was a significant difference in volume coagulation between those prostates removed at 4-9 days and those removed at 60-210 min after laser coagulation. In histological and MRI examination, however, there was a strong correlation with view to coagulation volume in histological and MRI examination. Using the SideFocus side-firing laser fiber, both treatment modalities showed comparable volume coagulation. Laser-induced changes are conclusively discernible by 4 days, MRI examination with an endorectal coil thus being perfectly suitable for assessment.