CT is the procedure of choice in evaluating disease extent in pleural-based tumors, as well as in pleural effusions. In particular, this modality can be helpful in determining chest wall, mediastinal, and diaphragmatic involvement by malignant mesothelioma. MR imaging should not be routinely employed in evaluation of these entities, and its use is limited to special anatomic areas (lung apex, diaphragmatic surface, heart and spine).