MR imaging of pediatric cardiac tumors previously diagnosed by echocardiography.

Ten children, ranging in age from 3 weeks to 11 years, with a history of primary cardiac tumors were studied by two-dimensional echocardiography and by ECG triggered magnetic resonance (MR) imaging (six of them had rhabdomyomas). Eighteen of 31 tumors with intracavitary extension diagnosed by echocardiography were detected by MR. In addition, three intracavitary tumors were found by MR but not by echocardiography. Only 2 of 15 intramural tumors detected by echocardiography were identified by MR. Magnetic resonance imaging is inferior to echocardiography in the detection of intramural rhabdomyomas, but superior in delineation of the intra- and extracardiac extension of nonrhabdomyomal tumors.