Enhancing PSMA PET/CT imaging of prostate cancer: investigating the impact of multiple time point evaluation, diuretic administration, cribriform pattern, and intraductal carcinoma.

Objective: Our objective was to correlate staging PSMA PET imaging parameters to final histopathology. Second objective was to assess the performance of standard versus delayed PSMA PET to detect primary prostate tumor.

Methods: Thirty-one patients (mean age, 61.4 ± 8.2) who underwent radical prostatectomy and preoperative staging PSMA PET scans were included in the study. After defining dominant lesion in pathology, correlations with PET images were performed. Additionally, two physicians blind to clinical and pathological information retrospectively reviewed staging Ga-68 PSMA PET scans with standard and delayed imaging.

Results: Dominant lesion SUV's increased with time 8.2(± 4.5), 10(± 7.1), and 10.2(± 7.8) at 1, 2, and 3 h (P = .03 T1-T3). WHO Grade group 3 had highest SUV (group 3 11.9 ± 5.6 vs. group 2 7.9 ± 1.5, p = .02). Addition of cribriform pattern on intraductal component was associated with higher SUV's (11 ± 2.9 vs. 6.5 ± 2.1, p = .01) and higher Gleason four ratios (64 ± 9% vs. 37 ± 17%, p = .01). Intraductal carcinoma was associated with larger tumors (6.3 ± 2.3 cm vs. 2.6 ± 1.7 cm, p < .001). Physician sensitivities ranged from 61 to 81%. Excluding Gleason 3 + 3 lesions and small lesions (< 1 cm), sensitivities increased to 80-100%. Differences of sensitivity between different time points were not significant. Combined evaluation of all time points did not increase sensitivity.

Conclusions: Cribriform pattern correlates with higher Gleason 4 ratios and SUVs in PSMA PET. Intraductal carcinoma is associated with larger tumors but not higher Gleason 4 ratios and SUVs. Multiple late imaging times did not enhance tumor detection and may pose tolerability issues for some patients.