BackgroundThe inability to obtain complete diagnoses with transthoracic echocardiography in many adults with congenital heart disease provided the incentive to evaluate prospectively the individual and combined roles of magnetic resonance imaging (MRI) and transesophageal echocardiography (TEE) as “second-line” techniques for unresolved diagnostic problems.Methods and ResultsEighty-five patients were studied; 81 had MRI with a 0.5-T magnet to obtain spin- echo images, cine-MRI, and flow-velocity maps. Seventy-nine patients had TEE (37 biplane). A simple score (range, 0 to 1) was used for quantification of the results of MRI and TEE alone, for their comparison (in the 75 patients who had both), and for assessment of their combination. MRI, TEE, or their combination achieved a score of at least 0.75 in 18 of 25 diagnostic categories. A summary of the scores showed that for intracardiac anatomy. MRI scored 0.34, TEE scored 0.71 (P< .0001), and MRI plus TEE scored 0.84 (P< .003); for extracardiac anatomy, MRI scored 0.76, TEE scored 0.23 (P< .0001), and MRI plus TEE scored 0.84 (P= NS); and for hemodynamics and function, MRI scored 0.58, TEE scored 0.41 (P< .05), and MRI plus TEE scored 0.67 (P= NS). Total scores were MRI, 0.52; TEE, 0.50 (P= NS); and MRI plus TEE, 0.80 (P< .0001). MRI and TEE were inadequate for collateral and coronary arteries and pulmonary vascular resistance. Cine-MRI and flow-velocity maps comprised 43% of the MRI scores. Biplane TEE was better than single plane (scores of 0.59 versus 0.42,P< .0001).ConclusionsMRI and TEE are important and complementary “second-line” investigations for congenital heart disease. Analysis of their performance in a wide range of diagnostic categories provides guidelines for their judicious application. Where both are available, diagnostic catheterizations are either obviated or simplified.