Diagnostic Utility of 18F-DCFPyL PSMA PET/CT-Ultrasound Fusion Biopsies Across the Prostate Cancer Spectrum.

Background: Multiparametric MRI (mpMRI) is the standard imaging for detecting clinically significant prostate cancer (csPCa), but its limitations in MRI-invisible lesions demand complementary strategies. We aimed to evaluate the diagnostic utility of 18F-DCFPyL PSMA PET/CT-ultrasound fusion-guided biopsies in patients by determining the optimal cut-off for the lesion's standardized uptake value (SUV).

Methods: This was a single-center cohort study of 89 men with suspected PCa or low-risk PCa on active surveillance; all underwent PSMA PET/CT before biopsy. Transperineal PSMA PET/US fusion-guided biopsy was performed using the KOELIS Trinity platform. Biopsy outcomes, SUVmax values, and Gleason Grade Group (GGG) were analyzed. Outcomes were compared between MRI-visible and MRI-invisible lesions and among patients with and without prior biopsy. ROC curves and Youden's index were used to assess predictive accuracy and determine optimal SUVmax cut-offs. Decision curve analysis (DCA) was used to evaluate net clinical benefit.

Results: Eighty seven patients had an MRI, of which 34 lesions were MRI invisible. MRI-visible lesions had higher detection rates of PCa (83.3%) compared to MRI-invisible lesions (45.7%, p < 0.001). PET-only identified csPCa in 28% of MRI-invisible lesions (SUVmax mean 9.2 ± 1.8), with 32.4% of these patients proceeding to definitive treatment. Among patients with prior biopsies (60), 35.3% were upgraded, including 18.3% with reassuring/equivocal MRI (PI-RADS ≤ 3) findings. Overall, PET-guided biopsy detected PCa in 47.2% of all patients and csPCa in 24.7%. For the entire cohort, SUVmax ≥ 7.6 provided optimal discrimination between benign and csPCa (AUC = 0.73, 95% CI 0.64-0.82) with a clinical net benefit.

Conclusion: PSMA PET-fusion targeting can improve accuracy for PCa detection at SUV ≥ 7.7. PET-targeted biopsy can complement standard biopsy methods, especially in those with MRI-invisible lesions or patients with prior negative biopsies.