Assessing the patency of mediastinal and thoracic inlet veins: value of MR imaging.

To assess the accuracy of MR imaging in the evaluation of patients with suspected thoracic venous obstruction, hospital records and MR studies of 31 such patients were reviewed. Gradient-recalled echo, spin-echo, or cine MR techniques were used. In 26 of the 31 patients, venous obstruction was confirmed by CT, venography, sonography, surgery, or autopsy. Causes included tumor invasion, compression of veins, coagulopathy, or indwelling catheters. MR detected an abnormality of the superior vena cava in all 16 cases in which it was seen on other tests. Abnormality of the internal or external jugular veins was detected in all six cases in which other studies were abnormal. Abnormality of veins in the shoulder region was detected by MR in 10 of 12 patients in whom such disease was seen on other tests. The two interpretive errors were caused by nonocclusive clot, short (less than 2-cm) occlusions, and metallic artifact. Overall, MR correctly identified abnormality in 32 of 34 vessels (sensitivity, 94%). In all cases, a negative MR study was found to be a true negative (no false positives in 42 normal vessels; specificity, 100%). We conclude that MR is an accurate means of assessing patency of the thoracic inlet and mediastinal veins. Its noninvasive nature and multiplanar capability contribute to its usefulness in this clinical setting.