Comparison Of ¹⁸F-PSMA-PET/CT And MpMRI In The Diagnosis Of Pelvic Lymph Node Metastasis Of Prostate Cancer

Objective:To compare the diagnostic effectiveness of ¹⁸F prostate specific membrane antigen（PSMA）-1007 PET/CT and multiparametric magnetic resonance imaging（mpMRI）in prostate cancer pelvic lymph node metastases.Methods:Patients who underwent ¹⁸F-PSMA-1007 PET/CT and mpMRI examinations in Sichuan Cancer Hospital from September 2018 to December 2022 were retrospectively included.All patients were confirmed to be adenocarcinoma by prostate biopsy before surgery.All patients underwent RP combined with ePLND,and obtained postoperative pathological biopsy.The sensitivity,specificity,positive predictive value and negative predictive value of the two imaging methods was compared with Chi-square（χ2）test.Then Kappa test was used to compare the consistency between the two imaging examination methods and postoperative pathological results.P<0.05 was considered to be statistically significant.Results:Thirty-five patients were included in this study.Preoperative data showed that the average age was 68.1±6.4 years old,and serum PSA level was 34.6（15.6-100.0）ng/ml,including 4 patients with PSA<10 ng/ml,7 patients with PSA<10-20 ng/ml,and24 patients with PSA>20 ng/ml.Preoperative clinical T stages were 1 case at stage T1,22 cases at stage T2,7 cases at stage T3 and 5 cases at stage T4.Preoperative ISUP classification was divided into 3 cases in group 1,5 cases in group 2,7 cases in group 3,9 cases in group 4,and 11 cases in group 5.All but one of the remaining 34 cases were high risk patients.Postoperative pathology indicated positive lymph node metastases in12 patients,using pathology as the gold standard.Based on the number of patients,the sensitivity,specificity,PPV with addition of NPV in ¹⁸F-PSMA-1007 PET/CT which diagnosed the pelvic lymph node metastasis were 91.7%（11/12）,78.3%（18/23）,68.8%（11/16）with addition of 97.7%（18/19）,respectively,and Kappa value was found to be0.648.The sensitivity,specificity,PPV with addition of NPV in mpMRI which diagnosed the pelvic lymph node metastasis were 58.3%（7/12）,95.7%（22/23）,87.5%（7/8）with addition of 81.5%（22/27）,respectively,and Kappa value was found to be 0.587.The discrepancy of P value in sensitivity,specificity,PPV with addition of NPV between the two methods were 0.16,0.19,0.62 with addition of 0.38,respectively.Depending on the number of lymph node metastases,the sensitivity,specificity,PPV with addition of NPV in ¹⁸F-PSMA-1007 PET/CT were 91.2%（31/34）,98.0%（436/445）,77.5%（31/40）with addition of 99.3%（436/439）,respectively.The sensitivity,specificity,PPV with addition of NPV in mpMRI were 64.7%（22/34）,99.6%（443/445）,91.7%（22/24）with addition of 97.4%（443/455）,respectively.The discrepancy of P value in sensitivity,specificity,PPV with addition of NPV between the two methods were 0.02,0.06,0.19 with addition of 0.03,respectively.Conclusions:For PCa pelvic lymph node metastasis,the diagnostic sensitivity with addition of negative predictive value of ¹⁸F-PSMA-1007 PET/CT were higher than those of mpMRI,and the diagnostic specificity with addition of positive predictive value of mpMRI were higher than those of ¹⁸F-PSMA-1007 PET/CT.