Characterization of mediastinal lymphadenopathy with diffusion-weighted imaging

Abstract

Purpose To predict malignancy of mediastinal lymphadenopathy with diffusion-weighted imaging. Material and methods A prospective study was conducted on 35 patients with mediastinal lymphadenopathy (28 malignant and seven benign nodes). They underwent echoplanar diffusion-weighted magnetic resonance imaging of the mediastinum with b-factors of 0, 300 and 600 s/mm 2. 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<.05 was considered significant. Results The mean ADC value of malignant mediastinal lymphadenopathy (1.06±0.3×10 −3 mm 2/s) was significantly lower ( P=.001) than that of benign lymphadenopathy (2.39±0.7×10 −3 mm 2/s). There was an insignificant difference in the ADC values between metastatic and lymphomatous mediastinal lymph nodes ( P=.32) as well as within benign nodes ( P=.07). When an ADC value of 1.85×10 −3 mm 2/s was used as a threshold value for differentiating malignant mediastinal nodes from benign nodes, the best results were obtained with an accuracy of 83.9%, a sensitivity of 96.4%, a specificity of 71.4%, a negative predictive value of 95.2% and a positive predictive value of 77.1%. The area under the curve was 0.98. Conclusion Diffusion weighted magnetic resonance imaging is a promising noninvasive imaging modality that can be used for characterization of mediastinal lymphadenopathy and differentiation of malignant from benign mediastinal lymph nodes.