The role of conventional and functional endorectal magnetic resonance imaging in the decision of whether to preserve or resect the neurovascular bundles during radical retropubic prostatectomy

Abstract

Objective. Because the recovery of erectile function and the avoidance of positive surgical margins are important but competing outcomes, the decision whether to preserve or resect a neurovascular bundle (NVB) during radical prostatectomy (RP) is based on information concerning mostly the presence and location of extracapsular extension (ECE). Conventional endorectal magnetic resonance imaging (e-ctMRI) and functional endorectal MRI (e-ftMRI) of the prostate provide an excellent depiction of the pelvic and prostate anatomy, and are also useful in predicting the presence of prostate cancer as well as ECE, seminal vesicle invasion (SVI) and NVB involvement. Their predictive qualities, however, have shown significant interobserver variability. The aims of this study are to report on accuracy using e-ctMRI and e-ftMRI, and to assess their value in making the decision whether to preserve or resect the NVBs during RP. Material and methods. From 2004 to 2007, 75 consecutive patients with a biopsy-proven prostate cancer and satisfactory erectile function, who were scheduled to undergo RP, were subjected to e-ctMRI and e-ftMRI before surgery. Interpretation was performed by a highly experienced radiologist blinded to patient clinical data. All patients underwent RP and a nerve-sparing (NS) procedure was considered appropriate if the tumour did not extend outside the capsule in the posterolateral region of the prostate as assessed by the images. Results. An NSRP was performed in 78.7% of patients. Based on the e-ctMRI and e-ftMRI findings, the operative strategy was changed in 44% of patients. The findings favoured NVB preservation in 67% of patients with a high clinical probability of ECE, and opposed NVB preservation in 33% of patients with a low clinical probability of ECE. Based on the final histopathological findings, the surgical plan was successfully changed in all patients. The sensitivity, specificity and accuracy rate were 92%, 100% and 100% for ECE, SVI and NVB involvement, respectively, results which are higher than all other published international standards in this matter. Conclusions. e-ctMRI and e-ftMRI comprise a sufficient modality in detecting prostate cancer, ECE, SVI and NVB involvement. This technique seems to one of the most sensitive preoperative clinical staging methods for selective patients, and extremely useful for identifying candidates for an NSRP.

• Conventional endorectal MRI
• functional endorectal MRI
• nerve-sparing radical retropubic prostatectomy
• neurovascular bundle