Validation of real-time prostatic biopsies evaluation with fluorescence laser confocal microscopy

Background: Routine processing of prostate biopsies requires conventional steps that usually take a few days. The aim of this study was to validate the use of fluorescence laser confocal microscopy (FCM) for real-time diagnostics. Methods: We prospectively tested images from prostate needle biopsies (75 images were evaluated by FCM and conventional slides). Two pathologists reviewed the images and assessed agreements between FCM versus conventional slides and between pathologists (κ-values). Interpretation was performed on digital images from the VivaScope 2500 confocal microscope (MAVIG GmbH, Munich, Germany; Caliber I.D., Rochester, NY, USA) placed in the urological operating room. Cancerous versus benign tissue was the primary focus, then the application of the grading system. Results: Cancer was diagnosed in 24 conventional slides (on 75 images) in which agreement among pathologists was high for both conventional (κ=0.96) and FMC (κ=0.84). 1/24 (4%) was ISUP/WHO grade group I, 12/24 (50%) II, 8/24 (33%) III, 2/24 (8%) IV and 1/24 (4%) grade V. Near perfect agreement was obtained for grades I, IV and V (κ=0.85). Grade III values achieved a moderate agreement (κ=0.55). The mean time for laser scanning was 9 minutes. For the remaining non-tumor images, agreement was nearly perfect (κ=0.81). Conclusions: We validated the use of FCM for real-time cancer detection in prostate biopsies.