Diffusion-weighted Imaging (DWI) And Apparent Diffusion Coefficient (ADC) Value In Differential Diagnosis Of Hilar And Mediastinal Lymph Nodes Of Non-small Cell Lung Cancer

Objective:The aim of this study was to evaluate the capability and reliability of DWI for differentiation of metastatic versus non-metastatic mediastinal lymph nodes in patients with non-small cell lung cancer(NSCLC).Materials and Methods:45 consecutive patients with pathologically confirmed NSCLC underwent echo-planar diffusion-weighted magnetic resonance imaging of the mediastinum with b-factors of 600,800 and 1000 s/mm2. The apparent diffusion coefficient (ADC) values of the mediastinal lymph nodes were calculated. The ADC values were correlated with the biopsy results and statistical analysis was done. A value of P<0.05 was considered significant.Results:The mean ADC value of malignant mediastinal lymphadenopathy (1.73±0.24×10-3mm2/s) was significantly lower (P<0.05) than that of benign lymphadenopathy (2.67±0.16×10-3 mm2/s). There was an significant difference in the ADC values between metastatic and benign nodes ((P<0.05). There was insignificant difference in the ADC values between the metastatic lymph nodes of different pathologies. When an ADC value of 2.23×10-3 mm2/s was used as a threshold value for differentiating malignant mediastinal nodes from benign nodes, the best results were obtained with an accuracy of 82%, a sensitivity of 92%, a specificity of 71%, a negative predictive value of 90% and a positive predictive value of 76%.The area under the curve was 0.96.Conclusion:On the basis of our preliminary experience, DWI seems to be a feasible and reliable method to discriminate malignant from benign mediastinal lymph nodes in patients with NSCLC.