In order to establish normal values for left heart dimensions by magnetic resonance imaging (MRI), electrocardiographically gated MRI was performed in 16 normal asymptomatic subjects using a whole-body 0.6-T superconducting magnet with a spin-echo pulse sequence and an echo delay (TE) of 30 msec. Images were oriented along the long and short axes of the left ventricle in planes similar to two-dimensional echocardiograms (2DE). Comparable 2DE images were obtained for validation of the MRI measurements. The following measurements of the left heart were made at end diastole and end systole in both long- and short-axis views using both techniques: left ventricular cavity diameters, interventricular septum and posterior wall thicknesses at chordal and mid-papillary-muscle levels, and anteroposterior mid-left-atrial diameter. There was good correlation between the two techniques in a total of 141 measurements (MRI = 0.94 2DE + 1.42, p less than 0.0001, r = 0.97) and in the individual measurements considered sep...