Diffusion-weighted MR imaging of mediastinal lymphadenopathy in children

Purpose: To assess mediastinal lymphadenopathy in children with diffusion-weighted MR imaging. Materials and methods: Retrospective analysis of 29 consecutive children (18 boys and 11 girls aged 2–15 years) with mediastinal lymphadenopathy. They underwent single-shot echo planar diffusion-weighted MR imaging of the mediastinum with b factors of 0, 300, and 600 s/mm2. The ADC value of the mediastinal lymph nodes was calculated and correlated with biopsy results; statistical analysis was also performed. Results: The mean ADC value for malignant mediastinal lymphadenopathy (n = 20) (0.99 ± 0.18 × 10−3 mm2/s) was significantly lower (P = 0.001) than that for benign lymphadenopathy (n = 9) (1.35 ± 0.26 × 10−3 mm2/s). There was significant difference between ADC values for non-Hodgkin lymphoma and metastatic nodes (P = 0.04). For differentiating malignant from benign mediastinal lymphadenopathy, the best result was obtained when an ADC value of 1.22 × 10−3 mm2/s was used as a threshold value; area under the curve was 0.861, accuracy 93.1 %, sensitivity 100 %, specificity of 77.8 %, positive predictive value 90.9 %, and negative predictive value of 100 %. Conclusion: Diffusion-weighted MR imaging is a promising non-invasive imaging modality that can be used for differentiation of malignant from benign mediastinal lymphadenopathy in children.