title: Preoperative prediction of neurovascular bundle involvement of localized prostate cancer by combined T2 and diffusion-weighted imaging of magnetic resonance imaging, number of positive biopsy cores, and Gleason score.
abstract: Because recovery of erectile function and avoidance of positive surgical margins are important but competing outcomes with prostate cancer therapy, the decision to preserve or resect a neurovascular bundle (NVB) during laparoscopic radical prostatectomy (LRP) should be firmly based on information concerning the presence and location of extracapsular extension. In the current retrospective study, the propriety of actual decisions was assessed using preoperative magnetic resonance imaging (MRI), combining T2-weighted imaging (T2WI) with diffusion-weighted imaging (DWI), the apparent diffusion coefficient (ADC), numbers of positive biopsy cores, tumor volume and the Gleason score. MRI before prostate biopsy was performed in 35 patients who underwent LRP for clinically localized prostate cancer. A single radiologist retrospectively assessed whether the tumor localization, capsular penetration, seminal vesicle invasion, NVB involvement, and MRI findings correlated with the postoperative histological results. With the postoperative specimens, 83 lesions demonstrated a Gleason score of 6 or more. Using T2WI with and without DWI and ADC, 39 and 27 of 54 lesions were correctly identified, respectively, the difference being significant. For cancers in the transitional zone, using a threshold Gleason score of 3 or greater, sensitivity was also significantly higher for T2+DWI+ADC than for T2WI alone. Of 35 patients, using all available clinical information (biopsy results including Gleason score, tumor location, percentage of positive biopsy cores, and the percentage of tumor-involved core tissue), we found that the preoperative and postoperative staging were concordant in 25 cases. There is no universal consensus for nerve-sparing LRP; therefore, we performed an additional analysis using simplified clinically defined selection criteria (PSA level >15ng/mL, cT2, less than two positive biopsy scores in the unilateral lobe and less than 30% tumor volume, and a Gleason score of 6). Using this criteria, we selected 12 of 35 patients, and the detection rate of NVB involvement by MRI combined T2WI + DWI + ADC maps was 100% in their 30 lesions, and therefore we consider it safe to perform nerve-sparing LRP using our criteria. Our findings suggest that NVB can be safely preserved in patients with low-grade tumors using simplified clinically defined selection criteria to determine margin involvement.
authors.affiliation: Department of Urology, East Medical Center Higashi Municipal Hospital City of Nagoya, Nagoya, Japan. rx-nike@hotmail.co.jp
authors.forename: Taku
authors.initials: T
authors.lastname: Naiki
authors.forename: Takehiko
authors.initials: T
authors.lastname: Okamura
authors.forename: Daisuke
authors.initials: D
authors.lastname: Nagata
authors.forename: Yuji
authors.initials: Y
authors.lastname: Mori
authors.forename: Noriyasu
authors.initials: N
authors.lastname: Kawai
authors.forename: Kumiko
authors.initials: K
authors.lastname: Ogawa
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Akita
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Hashimoto
authors.forename: Keiichi
authors.initials: K
authors.lastname: Tozawa
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Kohri
mesh_terms: D000368:Aged; D001706:Biopsy / Q000379:methods; D007172:Erectile Dysfunction / Q000517:prevention & control; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading / Q000379:methods; D009367:Neoplasm Staging / Q000379:methods; D010410:Penile Erection / Q000502:physiology; D011183:Postoperative Complications / Q000517:prevention & control; D011237:Predictive Value of Tests; D011467:Prostate / Q000294:innervation* / Q000473:pathology / Q000601:surgery*; D011468:Prostatectomy / Q000009:adverse effects* / Q000379:methods; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery*; D020127:Recovery of Function / Q000502:physiology