Qualitative Diagnostic Value of Different Apparent Diffusion Coefficients on Metastatic Pelvic Lymph Nodes in Prostate Cancer

Objective To evaluate the diagnostic value of different apparent diffusion coefficients (ADC) on metastatic pelvic lymph nodes in prostate cancer.

Methods We collected the clinical and MRI data of 58 prostate cancer patients with pelvic lymphadenectasis. The ADC values of enlarged pelvic lymph nodes were obtained by partial measurement (ADC_partial) and overall measurement (ADC_overall), and the consistency was analyzed by Bland-Altman method. The diagnostic efficacy of the two ADC values was compared by the Receiver operating curve (ROC).

Results A total of 69 enlarged lymph nodes were involved, including 22 inflammatory lymph nodes and 47 metastatic lymph nodes. Bland-Altman results showed that 8.7% (6/69) of ADC values obtained by ADC_partial and ADC_overall were beyond the 95% limit of agreement (95% LoA), indicating poor consistency and suggesting that ADC partial and ADC_overall were two different methods for measuring ADC values of lymph nodes and could not be replaced by each other. ROC curves showed that the sensitivity, specificity, the area under the curve of ADC_partial and ADC_overall were 82.98%, 90.91%, 0.927 and 89.36%, 95.45%, 0.962, respectively. The diagnostic efficacy of ADC_overall was better than that of ADC_partial (Z=2.013, P=0.044).

Conclusion Both ADC_partial and ADC_overall have great advantages in the qualitative diagnosis of metastatic pelvic lymph nodes in prostate cancer, and ADC_overall has higher diagnostic efficiency.