Assessment of left ventricular wall thickness in healed myocardial infarction by magnetic resonance imaging.

The ability of magnetic resonance imaging (MRI) to detect and localize healed myocardial infarction (MI) was assessed. Seventeen consecutive patients with healed MI assessed by biplane contrast ventriculography underwent MRI using oblique imaging planes. Seven normal subjects underwent MRI as controls. In each patient, ventriculography identified regional wall motion abnormalities. MRI, performed with a 0.15-Tesla resistive magnet and oblique imaging planes relating to the left ventricle, detected zones of regional wall thinning conforming to the wall motion abnormalities localized by ventriculography in 16 patients. In these patients, adjacent areas of intact myocardium were identified in areas shown by ventriculography to be normal. The left ventricular wall thickness at the site of MI was significantly less than adjacent noninfarcted myocardium (p less than 0.001) and normal hearts (p less than 10(-6)). The ratio of the thickness of the infarct to adjacent normal wall averaged 0.40 (range 0.22 to 0.62). MRI could differentiate healed MI from adjacent noninfarcted myocardium and normal hearts.