POSLUMA PET Imaging for PI-RADS 3 Prostate Lesions

Men aged 18 years or older with a PI-RADS 3 lesion identified on multiparametric MRI within the prior 4 weeks and a clinical indication for prostate biopsy will be consecutively enrolled. After written informed consent, participants will undergo POSLUMA PET/MRI or PET/CT. POSLUMA will be administered as an intravenous bolus at 296 MBq (8 mCi), and imaging will begin approximately 60 minutes after administration. PET-derived metrics, including SUVmax, PRIMARY score, lesion-to-background ratio, and lesion volume, will be recorded. MRI features and clinical parameters, including PSA, PSA density, and free-to-total PSA ratio, may also be collected. The reference standard will be histopathology from targeted biopsy of the PI-RADS 3 lesion together with systematic prostate biopsy. Diagnostic performance will be evaluated using lesion-level area under the receiver operating characteristic curve, sensitivity, specificity, positive predictive value, and negative predictive value. The study will also estimate biopsy avoidance and missed clinically significant prostate cancer rates and explore multivariable models combining PET, MRI, and clinical variables. Participants should not expect direct clinical benefit, and the research PET result will not alter biopsy decisions or other standard care.