Margin evaluation with fluorescence confocal microscopy during minimally invasive radical prostatectomy

OBJECTIVES: To demonstrate the reliability and diagnostic accuracy of fluorescence confocal microscopy (FCM) analysis of surgical margins during minimally invasive radical prostatectomy (RP). PATIENTS AND METHODS: From January 2022 to February 2023, we enrolled 100 consecutive patients in this single-centre, prospective, non-randomised trial (C2021/32). The VivaScope® 2500M-G4 microscope (Mavig GmbH, Munich, Germany), a laser scanning microscope designed for rapid acquisition of high-resolution digital images, was employed. Following surgery, each posterolateral prostatic margin was analysed using FCM and reviewed by two expert urological pathologists. This study aimed to assess the accuracy of FCM in evaluating surgical margins during RP, comparing the diagnostic accuracy of FCM to final anatomical pathology (AP) and assessing the inter-rater agreement between two urological pathologists (Cohen's kappa agreement). RESULTS: A total of 100 patients (i.e., 200 surgical margins) were included. Overall, 37 margins in 33 patients were positive according to FCM. At final pathology, 38 specimens in 29 patients were positive. On a per-patient analysis sensitivity, specificity, positive predictive value, and negative predictive value of FCM were 65.5%, 80.2%, 57.5%, and 85.0%, respectively. On a per-margin analysis, they were 60.5%, 91.3%, 62.1%, and 90.7%, respectively. The inter-rater agreement was 0.64 and 0.61 for per-patient and per-margin analysis, respectively. CONCLUSIONS: Fluorescence confocal microscopy is a feasible technology to be employed during RP, offering a good diagnostic accuracy without distorting final AP.