Comparison of the predictive value of multiparametric MRI and prostate-specific membrane antigen PET/CT for pelvic lymph node metastasis in prostate cancer

Abstract

Objective: To compare the diagnostic performance of multiparametric magnetic resonance imaging (mpMRI) and prostate-specific membrane antigen (PSMA) PET/CT in detecting pelvic lymph node metastasis in prostate cancer. Methods: This is a retrospective case series study. A retrospective analysis was conducted on the data of 115 prostate cancer patients who underwent both mpMRI and PSMA PET/CT before undergoing radical prostatectomy and extended pelvic lymph node dissection at the Department of Urology, Xiangya Hospital, Central South University, between March 2020 and September 2023. The age (M(IQR)) was 67(10) years (range: 45 to 84 years), and the body mass index was 24(4) kg/m2 (range: 18 to 30 kg/m2). Pathological and imaging data were obtained from the patients. Lymph node pathology results were used as the gold standard to evaluate the diagnostic performance of mpMRI and PSMA PET/CT for detecting pelvic lymph node metastasis in PCa through diagnostic evaluation tests. Comparisons between groups were performed using independent samples t-test, Mann-Whitney U test, or χ2 test. Results: The positive rate for detecting pelvic lymph node metastasis was 18.3% (21/115) with mpMRI and 25.2% (29/115) with PSMA PET/CT. The pathological positive rate for lymph nodes was 28.7% (33/115). In patient-based analysis, the diagnostic sensitivity of PSMA PET/CT was significantly higher than that of mpMRI (63.6% vs. 30.3%, χ2=7.36, P=0.007). In lesion-based analysis, both the sensitivity and positive predictive value of PSMA PET/CT were significantly higher than those of mpMRI (sensitivity: 68.0% vs. 21.6%, χ2=42.20, P<0.01; positive predictive value: 50.0% vs. 23.1%, χ2=7.54, P=0.006). Conclusions: PSMA PET/CT and mpMRI both demonstrates good specificity in predicting pelvic lymph node metastasis in prostate cancer. However, PSMA PET/CT is significantly superior to mpMRI in terms of sensitivity and the detection rate of pathologically positive lymph nodes.