EVALUATION OF AV CANAL DEFECTS USING ECG-GATED NMR IMAGING

Preoperative assessment of AV canal defects requires precise delineation of ventricular, septal and valvular morphology. In particular, recognition of ventricular hypoplasia is critical since it may preclude successful surgical correction. This evaluation is difficult even with cineangiography and 2-dimensional echocardiography. Nuclear magnetic resonance imaging (NMRI) is a new technique capable of providing excellent spatial and contrast resolution of cardiovascular structures without the need for contrast agents. We have used ECG-gated NMRI at 0.3T to evaluate 6 children with AV canal defects, including 3 with balanced chamber sizes, 2 with hypoplasia of the left ventricle and 1 hypoplastic right ventricle. All 6 defects were readily imaged and the 3 hypoplastic ventricles identified. AV valve morphology could be determined in 5 patients. Other frequently seen structures included papillary muscles, chordae tendinae and moderator bands. We conclude that gated NMRI is a valuable adjunct to angiography and echocardiography in the preoperative evaluation of children with AV canal defects.