Prospective evaluation of 68Gallium‐prostate‐specific membrane antigen positron emission tomography/computed tomography for preoperative lymph node staging in prostate cancer

Objectives To assess the accuracy of 68Gallium‐prostate‐specific membrane antigen (68Ga‐ PSMA ) positron emission tomography/computed tomography ( PET / CT ) for lymph node ( LN ) staging in intermediate‐ and high‐risk prostate cancer ( PC a). Materials and Methods From April to October 2015, 30 patients with intermediate‐ ( n = 3) or high‐risk ( n = 27) PC a were prospectively enrolled. Patients underwent preoperative 68Ga‐ PSMA PET / CT . Both visual and semi‐quantitative analyses were undertaken. Subsequently, all patients underwent radical prostatectomy ( RP ) with an extended pelvic lymph node dissection. The sensitivity, specificity, and positive ( PPV ) and negative predictive value ( NPV ) for LN status of 68Ga‐ PSMA were calculated using histopathology as reference. Results Eleven patients (37%) had lymph node metastases (LNMs); 26 LNM s were identified in the 11 patients. Patient analysis showed that 68Ga‐ PSMA PET / CT had a sensitivity of 64% for the detection of LNM s, its specificity was 95%, the PPV was 88%, and the NPV was 82%. In total, 180 LN fields were analysed. In the LN ‐region‐based analysis, the sensitivity of 68Ga‐ PSMA PET / CT for detection of LNM s was 56%, the specificity was 98%, the PPV was 90% and the NPV was 94%. The mean size of missed LNM s was 2.7 mm. Receiver‐operating characteristic curve analysis showed a high accuracy of maximum standardized uptake value ( SUV max ) for the detection of LNM s, with an area under the curve of 0.915 (95% confidence interval 0.847–0.983); the optimum SUV max was 2.0. Conclusions In patients with intermediate‐ to high‐risk PC a, 68Ga‐ PSMA PET / CT had a high specificity and a moderate sensitivity for LNM detection. 68Ga‐ PSMA PET / CT had the potential to replace current imaging for LN staging of patients with PC a scheduled for RP .