Delayed PSMA PET/CT Imaging for Diagnosing Clinically Significant Prostate Cancer in Biopsy-Naïve Men With Suspected Prostate Cancer

Study Design and Objective This is a prospective, multicenter diagnostic accuracy study designed to evaluate whether delayed PSMA PET imaging improves diagnostic efficacy for clinically significant prostate cancer (csPCa) compared with standard imaging in patients with suspected newly diagnosed, treatment-naïve prostate cancer. Each patient serves as their own control. Imaging Protocol All enrolled patients undergo dual-time-point PSMA PET/CT before biopsy: 1. Standard acquisition: whole-body imaging at approximately 60 minutes post-injection. 2. Delayed acquisition: pelvic-focused imaging at 2-3 hours post-injection. Reference Standard All patients undergo prostate biopsy using 12-core systematic biopsy plus targeted biopsy when indicated. Histopathology serves as the reference standard. csPCa is defined as ISUP grade group ≥2. Primary Outcome To compare the area under the receiver operating characteristic curve (AUC) of delayed SUVmax versus standard SUVmax for detecting csPCa, and to determine whether delayed imaging is superior to standard imaging. Secondary Outcomes 1. Optimal diagnostic thresholds for delayed SUVmax and ΔSUVmax, with internal validation; 2. Negative predictive value (NPV) and biopsy avoidance potential (especially in PI-RADS 4-5 patients); 3. Diagnostic performance in key subgroups (PI-RADS 2-3 vs. 4-5); 4. Proportion of patients with additional csPCa lesions detected only on delayed imaging; 5. Proportion of patients whose management would change after incorporating delayed results; 6. Exploratory subgroup analyses by PSA level, PSA density, and combined gray-zone subgroups. Statistical Analysis The primary analysis will compare paired AUCs using the DeLong test . Secondary analyses will use appropriate paired tests with adjustment for multiple comparisons. Missing data will be handled by complete-case analysis. Data Monitoring An independent data monitor reviews data integrity and protocol adherence. No interim analysis is planned. The study complies with the Declaration of Helsinki and local regulations.