Identification of peri-prostatic neurovascular fibers before and after radical prostatectomy by means of diffusion tensor imaging (DTI) with clinical correlations: initial experience

Abstract

Aim: To evaluate if Diffusion Tensor Imaging (DTI) is able to detect morphological changes of peri-prostatic neurovascular fibers (PNF) before and after robot-assisted radical prostatectomy (RARP) and if these changes are related to urinary incontinence (UI) and erectile dysfunction (ED). Materials and methods: From October 2014 and August 2017 26 patients with biopsy-proven prostate cancer underwent prostatic multi-parametric magnetic resonance imaging (mp-MRI) including DTI sequencing before and six months after, RARP. Images were analyzed by placing six regions of interest (ROI) respectively at the base, mid-gland and apex, one for each side, to obtain tractography reconstruction of the PNF. Patients were asked to complete an International Consultation Incontinence Questionnaire – Short Form (ICIQ-SF) and International Index of Erectile Function (IIEF-5) questionnaires before RARP and 6 months postoperatively. Fractional anisotropy (FA), number (N) and length (L) of PNF before and after RARP were compared by means of Student's t-test; Spearman test was used to evaluate the correlation between DTI parameters and questionnaires scores. We observed a significant difference in N values before and after RARP (p<0.001) and a negative correlation between IIEF-5 score and post-operative FA values at both the right (rho=-0.42; p= 0.0456) and left (rho=- 0.66; p=0.0006) base of the prostate. DTI with tractography of PNF is able to detect quantitative changes in N, L and FA values in PNF after RARP. In particular we observed an inverse correlation between FA of PNF and ED at 6 months after RARP. Further investigations are needed to confirm this trend.