Assessment of Mediastinal Tumors With Diffusion-Weighted Single-Shot Echo-Planar MRI

Purpose: To assess the role of diffusion-weighted single-shot echo-planar magnetic resonance imaging (MRI) in patients with mediastinal tumors. Methods: Prospective study was conducted on 45 consecutive patients (29 male, 16 female, age 22-66 years, mean 41 years) with mediastinal tumor. They under-went diffusion-weighted single-shot echo-planar MRI, of the mediastinum with a b-factor of 0, 300, and 600 sec/mm(2). The apparent diffusion coefficient (ADC) value of, the mediastinal tumor was correlated with the histopathological findings. Results: The mean ADC value of malignant mediastinal tumors was 1.09 +/- 0.25 x 10(-3) mm(2)/sec, and of benign tumors was 2.38 +/- 0.56 x 10(-3) mm(2)/sec. There was a significant difference in the mean ADC value between malignant and benign tumors (P = 0.001) and within different grades of malignancy (0.001). When an ADC value of 1.56 x 10(-3) mm(2)/sec was used as a threshold value for differentiating malignant from benign tumor, the best results were obtained with an accuracy of 95%, sensitivity of 96%. specificity of 94%, positive predictive value of 94%, negative predictive value of 96%, and area under the curve of 0.938. Conclusion: The ADC value is a noninvasive parameter that can be used for differentiation of malignant from benign mediastinal tumors and grading of mediastinal malignancy.