Thoracic magnetic resonance imaging.

In our experience, MR has served largely as a problem-solving device, especially in those cases in which CT has proved equivocal. Magnetic resonance has been especially efficacious in evaluating cardiovascular pathology. Virtually the entire spectrum of aortic disease can be assessed accurately, making MR a reasonable alternative to CT or angiography in most cases. Indications for the use of MR in patients with thoracic neoplasia have also emerged. Magnetic resonance is more accurate than CT in assessing invasion of the chest wall and mediastinum. As a consequence, MR should be considered the imaging procedure of choice in patients with suspected Pancoast tumors. In some patients with lymphoma, MR can make a unique contribution by evaluating the response to therapy. Magnetic resonance also can be of value in assessing patients with signs of venous obstruction, especially when there is a contraindication to the use of intravenous contrast medium. Magnetic resonance is as accurate as CT in assessing most benign mediastinal pathology. The former study can easily differentiate atherosclerotic vessels or aneurysms from enlarged lymph nodes or masses, frequently obviating a more invasive study. It is especially efficacious in evaluating patients with cystic lesions, especially those with complex cysts not clearly of water density. In the hilum, MR can differentiate prominent hilar vessels from adenopathy or masses as reliably as CT. Again, in patients with renal failure or those who have documented allergies to iodinated contrast medium, MR should be the imaging procedure of choice to evaluate suspicious hila identified on plain chest radiographs. Magnetic resonance also can be used to differentiate central obstructing hilar tumors from peripheral collapsed lung. In certain cases, these findings may help determine resectability by demonstrating encasement of hilar and mediastinal vessels as well as the central airways. It should be anticipated that as technologic improvements continue to be made, MR will assume an increasingly important role in the imaging of thoracic disease.