PSMA-PI-RADS in 68Ga-PSMA-11 PET/MRI Improve the Differentiation of Naïve Prostate Cancer and Primary Staging: Pilot Study

1358 Objectives: To explore the clinical value of 68Ga-PSMA-11 PET/MRI in the differentiation and primary staging of prostate cancer naive prostate cancer, PSMA expression integrate into Prostate Imaging Reporting and Data System criteria (PSMA-PI-RADS) was explored. Materials and Methods: From July to November 2019, 73 patients suspected with PCa(PSA7.21~600 ng/ml)were recruited into this study, which was approved by ethics committee of Nanjing First Hospital. All patients underwent PET/MRI at 1h post-injection of 68Ga-PSMA-11(111-185×106MBq). PET, mpMRI, and combined 68Ga-PSMA-11 PET/MRI were independently evaluated. PI-RADS was used for MRI analysis. Tumor uptake was semi-quantitatively evaluated with the maximal standard uptake value (SUVmax) in the fusion image. ADC value of primary lesion was measured in ADC map(b=1500). The diagnostic efficacy of PET/MRI was evaluated by PSMA-PI-RADS. Final diagnosis was confirmed by biopsy and post-surgery histopathology. Results: Finally, 64 pts with PCa and 9 pts with BPH were finally confirmed .Among the 73 pts in this group, when PI-RADS score was only based on MRI, 4/73 had 2 scores; 3/73 had 3 scores; 18/73 had 4 scores; 48/73 had 5 scores; when PSMA-RADS comprehensive score was used, 1/73 had 2 scores; 7/73 had 3 scores; 8/73 had 4 scores; 57/73 had 5 scores. 68Ga-PSMA-11 PET/MRI diagnosed 65 cases of PCa, one of which was false-positive. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 100%, 90%, 98.4%, 100% and 98.6%, respectively. PCa often showed focal radioactive uptake, associated with focal low signal in T2WI, and limited dispersion. BPH showed slightly uneven PSMA uptake associated with uneven diffuse signals inT2WI and DWI. Capsule invasion was observed in 39 patients; Distant metastasis occurred in 22 patients. SUVmax of PCa was significantly higher than that of BPH, [(27.87±23.18.21) vs.(4.97±2.31), P<0.001]. ADC values of PCa were significantly lower than those of BPH, [(0.92±0.39)vs.(1.08±0.24)x10-3mm/s2,P<0.05]. SUVmax in PCa were positively correlated with PI-RADS and PSMA-RADS, (r=0.558,P<0.01; r=0.736, P<0.001). Gleason score were positively correlated with PI-RADS and PSMA-RADS, (r=0.794,P<0.001; r=0.834, P<0.01) Conclusions: 68Ga-PSMA-11 PET/MRI had great merits in the detection of primary prostatic lesion and seminal vesicle invasion. PSMA-RADS was significantly correlated with Gleason score. SUVmax and PSMA-RADS might serve as an important diagnostic tool for the differentiation of PCa from BPH.