The Additive Diagnostic Value of Prostate-specific Membrane Antigen Positron Emission Tomography Computed Tomography to Multiparametric Magnetic Resonance Imaging Triage in the Diagnosis of Prostate Cancer (PRIMARY): A Prospective Multicentre Study

Multiparametric magnetic resonance imaging (MRI) is validated for the detection of clinically significant prostate cancer (csPCa), although patients with negative/equivocal MRI undergo biopsy for false negative concerns. In addition, 68Ga-PSMA-11 positron emission tomography/computed tomography (prostate-specific membrane antigen [PSMA]) may also identify csPCa accurately. This trial aimed to determine whether the combination of PSMA + MRI was superior to MRI in diagnostic performance for detecting csPCa. A prospective multicentre phase II imaging trial was conducted. A total of 296 men were enrolled with suspected prostate cancer, with no prior biopsy or MRI, recent MRI (6 mo), and planned transperineal biopsy based on clinical risk and MRI. In all, 291 men underwent MRI, pelvic-only PSMA, and systematic ± targeted biopsy. Sensitivity, specificity, and predictive values (negative predictive value [NPV] and positive predictive value) for csPCa were determined for MRI, PSMA, and PSMA + MRI. PSMA + MRI was defined as negative for PSMA negative Prostate Imaging Reporting and Data System (PI-RADS) 2/3 and positive for either MRI PI-RADS 4/5 or PSMA positive PI-RADS 2/3; csPCa was any International Society of Urological Pathology (ISUP) grade group ≥2 malignancy. Of the patients, 56% (n = 162) had csPCa; 67% had PI-RADS 3–5, 73% were PSMA positive, and 81% were combined PSMA + MRI positive. Combined PSMA + MRI improved NPV compared with MRI alone (91% vs 72%, test ratio = 1.27 [1.11–1.39], p