PRIAPOS trial: new conception of pathogenesis of post-brahytherapy erectile dysfunction

Abstract

Objective: to study the anatomical-topographical relationship between the prostate gland (PG) and the vascular structures responsible for erection, to justify the new concept of erectile dysfunction pathogenesis after brachytherapy of prostate cancer (PCa).Materials and methods. The study included 66 patients with verified or suspected PCa. All patients performed magnetic resonance imaging 1.5 T in accordance with the established protocol (hybrid method of visualization of internal pudendal arteries (IPA)). 16 patients simultaneously performed computed tomography on a topometric tomography. The resulting images were analyzed using the Eclipse 4.0 (Varian Medical System, USA) system, which provides 3D models of PG, pelvic bones and critical structures of interest: IPA, cavernous crura and penile bulb.Results. The average volume of PG was 44.9 ± 18.7 (14.4—98.0) cm3. The width of penile bulb was 1.83 ± 0.38 (1.1—2.93) cm. According to the implantation technique of in brachytherapy, the damage to penile bulb can be observed in less than a fifth of patients — 18.5 % of cases.Analysis of the 3D models showed that the overlay of the distal third of the IPA on the predominantly anterior and, in part, lateral aspects of the PG was noted in 58 (87.9 %) of 66 observations. The average value of PG in a group with no interference was 25.7 ± 3.9 (18.2—29.9) cm3, with its presence — 47.6 ± 18.4 (14.4—98.0) cm3. The average length of the IPA, coinciding with the projection of the PG on the right and left is virtually no different (p >0.05) and is about 2.5 cm, and the maximum remote point of this combination lies in relation to the outer contour of the gland within 1 cm. The correlation analysis showed a strong direct correlation between the volume of PG with all the parameters of mutual spatial anatomy of the prostate and IPA (R = 0.63—0.71; p <0.0001).Conclusion. The anatomical-topographical relationship between PG and critical structures, among which the IPA plays a special role, points to the likely predominantly traumatic genesis of erectile dysfunction after PCa brachytherapy, as well as a number of other invasive procedures performed by perineal access (saturation biopsy).