Evaluating Biochemically Recurrent Prostate Cancer: Histologic Validation of 18F-DCFPyL PET/CT with Comparison to Multiparametric MRI

Background: Prostate cancer recurrence is found in up to 40% of men with prior definitive (total prostatectomy or whole-prostate radiation) treatment. Prostate-specific membrane antigen PET agents such as 2-(3-{1-carboxy-5-[(6-[18F]fluoro-pyridine 3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid (F-18-DCFPyL) may improve detection of recurrence compared with multiparametric MRI; however, histopathologic validation is lacking. Purpose: To determine the sensitivity, specificity, and positive predictive value (PPV) of F-18-DCFPyL PET/CT based on histologicanalysis and to compare with pelvic multiparametric MRI in men with biochemically recurrent prostate cancer. Materials and Methods: Men were prospectively recruited after prostatectomy and/or radiation therapy with rising prostate-specificantigen level (median, 2.27 ng/mL; range, 0.2-27.45 ng/mL) and a negative result at conventional imaging (bone scan and/or CT).Participants underwent F-18-DCFPyL PET/CT imaging and 3.0-T pelvic multiparametric MRI. Statistical analysis included Waldand modified chi(2) tests. Results: A total of 323 lesions were visualized in 77 men by using F-18-DCFPyL or multiparametric MRI, with imaging detection concordance of 25% (82 of 323) when including all lesions in the MRI field of view and 53% (52 of 99) when only assessing prostate bed lesions. F-18-DCFPyL depicted more pelvic lymph nodes than did MRI (128 vs 23 nodes). Histologic validation was obtainedin 80 locations with sensitivity, specificity, and PPV of 69% (25 of 36; 95% confidence interval [CI]: 51%, 88%), 91% (40 of 44; 95% CI: 74%, 98%), and 86% (25 of 29; 95% CI: 73%, 97%) for 18F-DCFPyL and 69% (24 of 35; 95% CI: 50%, 86%), 74% (31 of 42; 95% CI: 42%, 89%), and 69% (24 of 35; 95% CI: 50%, 88%) for multiparametric MRI (P =.95, P =.14, and P =.07, respectively). In the prostate bed, sensitivity, specificity, and PPV were 57% (13 of 23; 95% CI: 32%, 81%), 86% (18 of 21; 95% CI: 73%, 100%), and 81% (13 of 16; 95% CI: 59%, 100%) for 18F-DCFPyL and 83% (19 of 23; 95% CI: 59%, 100%), 52% (11 of 21; 95% CI: 29%, 74%), and 66% (19 of 29; 95% CI: 44%, 86%) for multiparametric MRI (P =.19, P =.02, and P=.17, respectively). The addition of F-18-DCFPyL to multiparametric MRI improved PPV by 38% overall (P =.02) and by 30% (P=.09) in the prostate bed. Conclusion: Findings with 2-(3-{1-carboxy-5-[(6-[18F]fluoro-pyridine 3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid (F-18-DCFPyL) were histologically validated and demonstrated high specificity and positive predictive value. In the pelvis, F-18-DCFPyL depicted more lymph nodes and improved positive predictive value and specificity when added to multiparametric MRI. (C) RSNA, 2020