18F-PSMA Cerenkov Luminescence and Flexible Autoradiography Imaging in a Prostate Cancer Mouse Model and First Results of a Radical Prostatectomy Feasibility Study in Men.

Intraoperative identification of positive resection margins (PRMs) in high-risk prostate cancer (PC) needs improvement. Cerenkov luminescence imaging (CLI) with 68Ga-PSMA-11 is promising, although limited by low residual activity and artificial signals. Here, we aimed to assess the value of CLI and flexible autoradiography (FAR) with 18F-PSMA-1007. Methods: Mice bearing subcutaneous PSMA-avid RM1-PGLS tumors were administered 18F-PSMA-1007, and PET/CT was performed. After the animals had been killed, organs were excised and measured signals in CLI and FAR CLI were correlated with tracer activity concentrations (ACs) obtained from PET/CT. For clinical assessment, 7 high-risk PC patients underwent radical prostatectomy immediately after preoperative 18F-PSMA PET/CT. Contrast-to-noise ratios (CNRs) were calculated for both imaging modalities in intact specimens and after incision above the index lesion. Results: In the heterotopic in vivo mouse model (n = 5), CLI did not detect any lesion. FAR CLI detected a distinct signal in all mice, with a lowest AC of 7.25 kBq/mL (CNR, 5.48). After incision above the index lesion of the prostate specimen, no increased signal was observed at the cancer area in CLI. In contrast, using FAR CLI, a signal was detectable in 6 of 7 patients. The AC in the missed index lesion was 1.85 kBq/mL, resulting in a detection limit of at least 2.06 kBq/mL. Histopathology demonstrated 2 PRMs, neither of which was predicted by CLI or FAR CLI. Conclusion: 18F-PSMA FAR CLI was superior to CLI in tracer-related signal detectability. PC was could be visualized in radical prostatectomy down to 2.06 kBq/mL. However, the detection of PRMs was limited. Direct anatomic correlation of FAR CLI is challenging because of the scintillator overlay.

Prostate specific membrane antigen-radio guided surgery using Cerenkov luminescence imaging-utilization of a short-pass filter to reduce technical pitfalls.

BACKGROUND: Intraoperative Cerenkov luminescence imaging (CLI) is a novel technique to assess surgical margins in patients undergoing nerve sparing radical prostatectomy (RP). Here, we analyze the efficacy of a 550-nm optical short-pass filter (OF) to improve its performance. METHODS: In this prospective single-center feasibility study ten patients with prostate cancer (PC) were included between December 2019 and April 2020, including three patients without tracer injection as a control group. After preoperative injection of 68-Ga-prostate-specific membrane antigen (PSMA)-11 followed by RP, CLI of the excised prostate and the incised index lesion was performed to visualize the primary tumor lesion. We compared the findings on intraoperative CLI to postoperative histopathology. Furthermore, CLI-intensities determined as tumor to background ratio (TBR) and contrast to noise ratio (CNR) were measured. RESULTS: Histopathology proved positive surgical margins (PSM) in 3 patients with corresponding findings in CLI. After magnetic resonance imaging (MRI)-informed incision above the index lesion 2 out of 3 prostates demonstrated elevated CLI signals with histopathological confirmation of PC cells. The use of the OF enabled a significant reduction of the area of the regions of interest from a median of 1.80 to 0.15 cm2 (reduction by 85%, P=0.005) leading to increased specificity. Signals due to PSMs were not suppressed by the 550-nm OF. The median TBR was reduced from 3.33 to 2.10. In all three patients of the control group elevated CLI intensities were detected at locations with diathermal energy deposition during surgery. After application of the 550-nm OF these were almost totally suppressed with a TBR of 1.10. Measurements of Cerenkov luminescence intensity with the 550-nm OF showed a significant Pearson's correlation of 0.82 between PSM and the elevated TBR (P=0.003) and a significant Pearson's correlation of 0.66 between PSM and elevated CNR (P=0.04). Measurements without the OF did not correlate significantly. CONCLUSIONS: Intraoperative 68-Ga-PSMA CLI in PC is a tool that warrants further investigation to visualize PSM especially in intermediate and high-risk PC. Intraoperative CLI benefits from usage of a 550-nm OF to reduce false-positive signals.

Multiparametric MRI and MRI/TRUS Fusion Guided Biopsy for the Diagnosis of Prostate Cancer.

Purpose of this chapter To demonstrate the timing, benefits, limitations and current controversies of multiparametric magnet resonance imaging (mpMRI) combined with fusion guided biopsy and consider how additional incorporation of multivariable risk stratification might further improve prostate cancer (PC) diagnosis. Recent findings MpMRI has been shown to add important information to the diagnostic pathway for prostate cancer. Fusion biopsy has also shown advantages in comparison to standard practice for biopsy-naïve men and men with previous biopsy in large prospective studies providing level 1b evidence. Adding upfront multivariable risk stratification followed by or combined with mpMRI diagnostic accuracy can further be improved. Regarding active surveillance (AS), mpMRI in combination with fusion biopsy can support initial candidate selection and may help to monitor disease progression. However, mpMRI and fusion biopsy are not without failure and conflicting data exists to what extend (systematic) biopsies can be omitted. Summary The integration of mpMRI into the diagnostic pathway for PC can add important information for further decision making, yet more prospective and randomized data is needed to establish reliable procedure standards after mpMRI acquisition.

Multiparametric MRI fusion-guided biopsy for the diagnosis of prostate cancer.

PURPOSE OF REVIEW: To discuss the timing, benefits, limitations and current controversies of multiparametric magnet resonance imaging (mpMRI) combined with fusion-guided biopsy and consider how additional incorporation of multivariable risk stratification might further improve prostate cancer diagnosis. RECENT FINDINGS: MpMRI has been proven advantageous over standard practice for biopsy-naïve men and men with previous biopsy in large prospective studies providing level 1b evidence. Upfront multivariable risk stratification followed by or combined with mpMRI further improves diagnostic accuracy. Regarding active surveillance, mpMRI in combination with fusion biopsy can support initial candidate selection and may help to monitor disease progression. mpMRI and fusion biopsy, however, do not spare failure and conflicting data exists to what extend (systematic) biopsies can be omitted. SUMMARY: Integration of mpMRI into the diagnostic pathway for prostate cancer is beneficial; yet more prospective and randomized data is needed to establish reliable procedure standards after mpMRI acquisition.

TOP: Prospective Evaluation of a Volume Based, Computer Assisted Method for Transperineal Optimized Prostate Biopsy.

OBJECTIVE: This study is a prospective evaluation of a volume-based, computer-assisted method for transperineal optimized prostate (TOP) biopsy. The TOP algorithm automates core planning for systematic prostate biopsies using the 3-dimensional organ contour and an alterable volume for tumors to be excluded. SUBJECTS AND METHODS: MRI-transrectal ultrasound fusion biopsy with MRI-targeted biopsies (TBs) and systematic-TOP biopsies were performed on 172 men between October 2013 and March 2014. Systematic biopsies were placed according to TOP for detection of tumor volumes >0.5 mL with a minimum of 80% organ coverage in prostates up to 50 mL (70% in larger organs). RESULTS: Median 24 TOP cores and 3 MRI-TBs have been placed. Prostate cancer (PCa) was detected in 112 of 172 (65%) of men; TOP detected 109 (97%) and TB 62 (55%). Significant cancer (Gleason score ≥7) was detected in 75 (44%) of men and of these TOP detected 73 of 75 (97%) and TB 51 of 75 (68%). Overall, systematic-TOP sampling significantly outperformed TB for the detection of both, all PCa as well as significant PCa (p < 0.0001, p = 0.0005). CONCLUSION: The TOP method is innovative by integrating the individual prostate volume and PCa volume detection thresholds. In the present cohort, it diagnosed more significant tumors than TB alone. However, at the same time, more low-risk tumors are detected.

Diagnostic Accuracy of Transperineal MRI Fusion Biopsy in Comparison to Transrectal Biopsy with Regard to Incidental Histopathological Findings in Transurethral Resection of the Prostate.

OBJECTIVE: To investigate the diagnostic accuracy of transperineal MRI/transrectal ultrasound (TRUS) fusion prostate biopsy vs. transrectal prostate biopsy in transurethral resection (TUR) specimen of men undergoing TUR of the prostate (TURP) for symptomatic bladder outlet obstruction. MATERIAL AND METHODS: From a database of 3,509 men receiving prostate biopsy, all those undergoing TURP and negative prostate biopsy (n = 95; 45 transrectal, 50 transperineal fusion) were analysed. TURP specimens were compared with regard to incidental prostate cancer. RESULTS: Pre- and peri-interventional parameters in transrectal vs. fusion biopsy groups for age (65.2 ± 7.8 vs. 65.5 ± 7.3 years; p = 0.84), prostate specific antigen (10.7 ± 8.5 vs. 10.9 ± 8.7 ng/mL; p = 0.93), preoperative prostate volume (72.5 ± 26.1 vs. 71.8 ± 28.1 mL; p = 0.91) and resected weight (43.7 ± 21.9 vs. 41.4 ± 20.7 g; p = 0.61) showed no significant differences. Analysing the TURP specimen, 5 incidental T1a prostate cancers were found (3 Gleason 3 + 3 = 6; 2 Gleason 3 + 4 = 7, all in the transrectal biopsy group). Although, more biopsy cores were obtained in the MRI/TRUS fusion biopsy group (26 cores [interquartile range, IQR 24-28] vs. 14 cores [IQR 12-24], p < 0.01), there was no statistical impact of the obtained number of cores (p = 0.9) on diagnostic accuracy. Statistical analyses revealed significantly better diagnostic accuracy favoring image-guided fusion biopsy (p = 0.02). CONCLUSIONS: Our findings showed that a combination of MRI-targeted and systematic transperineal prostate biopsy improves patient safety. This is associated with a combination of transperineal biopsy technique and pre-interventional MRI.