Assessment of Mediastinal Masses With Diffusion Weighted MR Imaging

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 .