Differentiation between benign and malignant mediastinal tumors as well as characterization and grading of malignancy is essential for treatment planning as well as for prognosis .~MRI presents valuable diagnostic information in assessing the mediastinum. In addition, special applications have been developed over recent years diffusion-weighted magnetic resonance imaging is one such technique The advent of echo-planar imaging technique has rendered diffusion weighted imaging of the abdomen and thoracic cavity possible .~Quantitative assessment of the mediastinal mass is possible by calculation of apparent diffusion co-efficient value ,which is related to the proportion of extracellular and intracellular component.~The apparent diffusion co-efficient is inversely correlated with tissue cellularity. It is lower in viable tumor tissue with densely packed diffusion-hindering obstacles than in tissue with less densely packed obstacles such as tumor necrosis and benign tissue .
Differentiation between benign and malignant mediastinal tumors as well as characterization and grading of malignancy which is essential for treatment planning as well as for prognosis