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Purpose Prostate speci c membrane antigen (PSMA) PET/CT is increasingly used in men with biochemical recurrence post-prostatectomy to detect local recurrence and metastatic disease at low PSA levels. The aim of this study was to assess patterns of disease detection, predictive factors and safety using 18 F-DCFPyL PET/CT versus diagnostic CT in men being considered for salvage radiotherapy with biochemical recurrence post-prostatectomy.Methods We conducted a prospective trial recruiting 100 patients with biochemical failure postprostatectomy (PSA 0.2-2.0ng/mL) in men referred for salvage radiotherapy from August 2018 to July 2020. All patients underwent a PSMA PET/CT using the 18 F-DCFPyL tracer and a diagnostic CT. The detection rates of 18 F-DCFPyL PET/CT vs diagnostic CT were compared and patterns of disease are reported. Clinical patient and tumour characteristics were analysed for predictive utility. Thirty-day postscan safety is reported.Results Of 100 patients recruited, 98 were suitable for analysis with a median PSA of 0.32ng/mL. 18 F-DCFPyL PET/CT was positive or equivocal in 52% compared to 19.6% for diagnostic CT. Local recurrence was detected on 18 F-DCFPyL PET/CT in 29.2%, nodal disease was seen in 29.6% and bony metastases in 7.1%. Both ISUP grade group (p = 0.003) and pre-scan PSA (p = 0.061) were signi cant predictors of 18 F-DCFPyL PET/CT positivity, and logistic regression generated probabilities combining the two showed improved prediction rates. No signi cant safety events were reported post 18 F-DCFPyL administration.Conclusions 18 F-DCFPyL PET/CT increases detection of disease in men with biochemical recurrence post-prostatectomy compared to diagnostic CT. Men being considered for salvage radiotherapy with a PSA > 0.2ng/mL should be considered for 18 F-DCFPyL PET/CT scan.

Objectives To assess the accuracy of multiparametric magnetic resonance imaging (mpMRI) for the detection of significant prostate cancer in men undergoing radical prostatectomy (RP) in an Australian multicentre setting, and to assess concordance between mpMRI and RP for local tumour staging and index lesion locations. Patients and Methods Men who underwent mpMRI within 12 months of RP between January 2013 and August 2016 at three Australian sites were included (Central Coast, NSW, St Vincents Hospital, Melbourne, Vic., and Bendigo Hospital, Vic.). The results of mpMRI were compared with the final RP specimen to analyse the performance of mpMRI for significant prostate cancer detection, index lesion localization, prediction of T3 disease and lymph node metastasis. A comparison between mpMRI cases performed using the technical and reporting specifications of Prostate Imaging Reporting and Data System (PI‐RADS) version 1 and version 2 was also performed. Data analysis was performed using spss 24.0. Results A total of 235 cases were included for analysis. mpMRI PI‐RADS score ≥3 had a 91% sensitivity and 95% positive predictive value (PPV) for significant prostate cancer at RP. The overall concordance between index lesion location on mpMRI and RP specimen was 75%. The sensitivity for predication of significant prostate cancer was higher in the PI‐RADS version 2 cases compared with PI‐RADS version 1 (87–99%; P = 0.005). Index lesion concordance was higher in the PI‐RADS version 2 group (68% vs 91%; P = 0.002). mpMRI had a 38% sensitivity, 95% specificity, 90% PPV and 57% negative predictive value for extraprostatic disease. Sensitivity for prediction of T3 disease improved from 30% to 62% (P = 0.008) with PI‐RADS version 2. Conclusions In patients undergoing RP, an abnormal mpMRI is highly predictive (95% PPV) of significant prostate cancer, with an index lesion concordance of 75%. There has been a significant improvement in accuracy after the adoption of PI‐RADS version 2 technical specifications and reporting criteria; however; further study is required to determine if this is attributable to improved experience with mpMRI or changes in the PI‐RADS system.

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