[Magnetic resonance imaging for cardiovascular masses].

We examined 10 patients with cardiovascular masses using 0.15 tesla permanent magnetic resonance imaging (MRI) incorporating an ECG-gated spin echo technique, and investigated the usefulness of MRI in the noninvasive diagnosis of cardiovascular masses. Patients were one with rhabdomyoma, one with leiomyosarcoma, one with malignant mesothelioma (diffuse type), three with pulmonary arterial invasions by lung carcinoma, one with left atrial invasion by lung carcinoma, and three with the superior vena cava (SVC) syndrome. 1. Each image obtained with TE of 40 msec, and TR of one R-R interval clearly defined the mass by its intermediate signal intensity. 2. In the case of rhabdomyoma occupying the right ventricle, leiomyosarcoma growing from the inferior vena cava into the right atrium and malignant mesothelioma diffusely invading the mediastinum, the morphology and the extent of each mass in relation to the surrounding structures were distinctly identified in the coronal, sagittal or oblique sections for situation, in addition to the routine transaxial section. 3. In the cases of pulmonary arterial invasion by lung carcinoma and the SVC syndrome, the masses invading the pulmonary artery or narrowing large vessels were clearly separated from adjacent structures on the sections through each of the large vessels. 4. In the case without left atrial invasion, which was proved by autopsy, a high intensity line due to mediastinal fat demarcated the mass distinctly. This finding is a useful sign for evaluating the extension of a tumor. 5. The image obtained with TE of 80 msec, and TR of double R-R interval (long SE image) showed a different contrast from the image obtained with TE of 40 msec and TR of one R-R interval. Leiomyosarcoma had a more heterogenous intensity on the long SE image which may result from a different T2 value caused by necrotic, edematous or fibrotic changes within the tumor. These results indicate that MRI also provides some information about the differentiation between benign and malignant masses.