Clinical NMR imaging of the chest and mediastinum

Nuclear magnetic resonance (NMR) imaging, using the spin-echo and inversion recovery techniques, provides an excellent demonstration of normal intrathoracic anatomy, and has proven useful in the diagnosis of a number of chest diseases. Because of the absence of NMR signal from rapidly flowing blood, vascular lesions can be easily diagnosed without the use of contrast agents, and mediastinal and hilar masses can be easily distinguished from normal or abnormal vessels. On the basis of T1 values, mediastinal masses can be distinguished from normal mediastinal tissues, and using T1 and T2 values, fluid within masses can be detected. Although NMR appears to offer no great advantage relative to CT in the diagnosis of mediastinal mass, small hilar masses are much more easily distinguished from normal hilar structures using NMR. Another significant advantage of NMR is its ability to directly image in the sagittal and coronal planes with good spatial resolution. In some patients, this can be helpful in the assessment of mediastinal masses. NMR may prove helpful in the evaluation of blood flow, the noninvasive diagnosis of pulmonary embolism, and in the quantitation of lung water.