Radiologic evaluation of the mediastinum.

New imaging techniques have had a major impact on radiologic evaluation of the mediastinum. Computed tomography has led the way in defining internal anatomy noninvasively. Ultrasound plays a small but well-defined role in the evaluation of certain mediastinal masses. Digital vascular imaging has, in certain instances, replaced conventional angiography, though it seems unlikely to render conventional angiography obsolete. Other modalities such as magnetic resonance imaging are being applied and promise to become even more important in the near future. Finally, mediastinal sampling by needle biopsy under radiologic guidance has been shown to be a reliable technique when appropriately utilized.