Evolution of Preprostatectomy Imaging to Improve Surgical Outcomes
By: Sang Hun Song, MD, PhD, Seoul National University Bundang Hospital, Seongnam, Korea; Sung Kyu Hong, MD, PhD, Seoul National University Bundang Hospital, Seongnam, Korea, Seoul National University College of Medicine, Korea | Posted on: 30 Aug 2023
Radical prostatectomy (RP) is the current gold standard for surgically resectable organ-confined prostate cancer. Over the years, the evolution of preoperative imaging techniques has played a crucial role in improving surgical outcomes and patient management at all stages, spanning from accurate histopathological staging with MRI-guided biopsy as well as localization and detection of missed tumor with the advent of novel positron emission tomography (PET) tracers.
Early conventional imaging traditionally relied on transrectal ultrasound (TRUS) and CT scans, which are still indispensable modalities for providing information on cancer detection and visualization of possible local/distant metastasis, as well as in performing targeted biopsy for precise Gleason grading. However, pre-RP evaluation with TRUS inevitably suffers from interobserver variability dependent on reader experience as well as relatively low accuracy for tumor extent including extracapsular extension (ECE) and seminal vesical invasion, not to mention the overall low sensitivity and specificity for significant cancer at 40%-50%.1 Incorporation of power Doppler as well as microbubble contrast-enhanced TRUS does show moderate benefit in improving diagnostic sensitivity of biopsy, but advantages in RP outcome are limited in localized disease.2
MRI has emerged as a powerful tool in preoperative assessment for RP. Multiparametric (mp) MRI combines anatomical and functional imaging, enabling the detection and localization of prostate tumors with greater precision. Defined as the combination of T2-weighted imaging with at least 2 functional techniques such as diffusion-weighted imaging, dynamic contrast-enhanced, or magnetic resonance spectroscopic imaging, mpMRI helps assess the presence of significant cancer, predict organ-confined disease, and identify ECE and seminal vesicle invasion. With the updated PI-RADS (Prostate Imaging Reporting & Data System) implemented in 2014, MRI has revolutionized the staging and risk stratification of prostate cancer, aiding surgical planning and patient selection for RP with high sensitivity and specificity for ECE and seminal vesical invasion, although variable by institutional technique and study population.3 Higher PI-RADS scores are associated with adverse RP pathological features including higher Gleason scores4 and have been associated with increased biochemical recurrence after RP. As such, unfavorable features at preoperative and even prebiopsy mpMRI may be used for choosing which patients may benefit from RP rather than active surveillance.
From a functional aspect, preoperative MRI allows the surgeon to accurately assess the likelihood of achieving a margin-free status at RP and thus guides the decision of whether to undergo intraoperative neurovascular bundle preservation, which may minimize the rate of postoperative functional morbidity including incontinence and erectile dysfunction. By allowing spatial visualization of tumor extent and adjacent structures, MRI has been shown to improve the surgeon’s decision to perform nerve-sparing RP, especially in the choice of which side may be safely preserved without risking positive margin and subsequent recurrence.5
Recent advancements in PET imaging, particularly the use of prostate-specific membrane antigen (PSMA) tracers (68Ga-PSMA-11), have outperformed 18F-fluciclovine PET in postoperative settings and have shown promising results in preoperative assessment for RP.6 PSMA-PET imaging provides enhanced detection of recurrent or metastatic disease, lymph node involvement, and distant metastases, offering valuable information for surgical planning, including the identification of patients suitable for salvage RP after biochemical recurrence.7 Preoperative evaluation with PSMA-PET may indicate patients who may benefit from extended pelvic lymph node dissection,8 and patients with high uptake may require a nonnerve-sparing approach due to a higher rate of nonlocalized disease.9
The accurate assessment of tumor extent and localization helps the surgeon plan the surgical approach, optimize nerve-sparing techniques, and minimize the risk of positive surgical margins. Additionally, preoperative imaging aids in identifying patients who may benefit from neoadjuvant therapies to downsize tumors or target nodal disease before surgery. By tailoring the surgical approach based on preoperative imaging findings, surgeons can optimize the balance between cancer control and preservation of urinary continence and sexual potency. Currently, no single imaging technique can substitute all other modalities, and combination of different methods seems to best optimize surgical outcome. Results from ongoing trials of PSMA-PET to guide surgery (NCT04936334) and newer preoperative imaging models including whole body MRI hold promise for further change in the near future.
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- Yunkai Z, Yaqing C, Jun J, et al. Comparison of contrast-enhanced ultrasound targeted biopsy versus standard systematic biopsy for clinically significant prostate cancer detection: results of a prospective cohort study with 1024 patients. World J Urol. 2019;37(5):805-811.
- Pinto F, Totaro A, Palermo G, et al. Imaging in prostate cancer staging: present role and future perspectives. Urol Int. 2012;88(2):125-136.
- Hong SK, Song SH, Kim HJ, Lee HS, Nam JH, Lee SB. Temporal changes of PIRADS scoring by radiologists and correlation to radical prostatectomy pathological outcomes. Prostate Int. 2022;10(4):188-193.
- McClure TD, Margolis DJ, Reiter RE, et al. Use of MR imaging to determine preservation of the neurovascular bundles at robotic-assisted laparoscopic prostatectomy. Radiology. 2012;262(3):874-883.
- Calais J, Ceci F, Eiber M, et al. 18F-fluciclovine PET-CT and 68Ga-PSMA-11 PET-CT in patients with early biochemical recurrence after prostatectomy: a prospective, single-centre, single-arm, comparative imaging trial. Lancet Oncol. 2019;20(9):1286-1294.
- Wenzel M, Hussein R, Maurer T, et al. PSMA PET predicts metastasis-free survival in the setting of salvage radiotherapy after radical prostatectomy. Urol Oncol. 2022;40:7.e1-7.e8.
- Baas DJH, Schilham M, Hermsen R, et al. Preoperative PSMA-PET/CT as a predictor of biochemical persistence and early recurrence following radical prostatectomy with lymph node dissection. Prostate Cancer Prostatic Dis. 2022;25(1):65-70.
- von Klot CJ, Merseburger AS, Boker A, et al. 68Ga-PSMA PET/CT imaging predicting intraprostatic tumor extent, extracapsular extension and seminal vesicle invasion prior to radical prostatectomy in patients with prostate cancer. Nucl Med Mol Imaging. 2017;51(4):314-322.