The integrated diagnostic strategy of performing PSMA PET/CT followed by MRI improves the diagnostic accuracy of prostate cancer.

Abstract

PRIMARY score uses intraprostatic uptake patterns and uptake intensity of PSMA and has good performance in identifying clinically significant prostate cancer (csPCa). However, diagnostic accuracy is not satisfying in patients with PRIMARY score of 3 and 4, which may account for the relatively low specificity of PRIMARY score. MRI may improve the accuracy of PRIMARY score. This study aims to investigate the added value of bpMRI to Al¹⁸F-NOTA-PSMA-617 PET/CT in diagnosis of csPCa. This is a retrospective analysis of a prospectively collected dataset. Al¹⁸F-NOTA-PSMA-617 PET/CT and bpMRI were performed within 3 months in patients with suspected PCa. PRIMARY scores were evaluated in a blinded manner by two nuclear medicine physicians independently. Lesions with PRIMARY score of ≥ 3 were classified as malignant. Besides, lesions with PRIMARY score 3 or 4 underwent further diagnostic refinement via bpMRI. Pathology was obtained within three months after completing bpMRI and PSMA PET/CT. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. 181 patients were included in this analysis. The incidence of csPCa in PRIMARY score 1-5 is 0 (0/18), 7.7% (3/39), 15.4% (2/13), 55.0% (22/40) and 87.3% (62/71). The sensitivity, specificity, PPV and NPV of PRIMARY score are 96.6%, 58.7%, 69.4% and 94.7%. After diagnostic refinement via bpMRI in patients with PRIMARY score 3 or 4, 22 patients were changed to the negative group. Only 3 of 22 patients, all with ISUP 2, had csPCa. The sensitivity, specificity, PPV, and NPV of the new diagnostic pathway were 93.3%, 79.3%, 81.4% and 92.4%. The specificity increased significantly (p < 0.001) while the sensitivity remained the same (p = 0.25). Addition of bpMRI in patients with PRIMARY scores of 3 or 4 improved specificity for diagnosing csPCa while maintaining comparable sensitivity levels. Only a small proportion of patients were additionally missed, all of whom had low pathological grades. The novel diagnostic strategy represents an effective, safe, and efficient approach to identify csPCa with significant clinical application value.