What is the most sensitive imaging technique for the detection of myocardial infarction?
Cardiac MRI with delayed phase postcontrast images (i.e., a “viability study”) is the most sensitive imaging technique. Echocardiography can detect areas of myocardial wall thinning or abnormal myocardial contraction. Cardiac single photon emission computed tomography (SPECT) can detect areas of nonviable myocardium. MRI has greater specificity than echocardiography, however, and greater spatial resolution and sensitivity than SPECT. Acute or chronic myocardial infarction shows accumulation of gadolinium-based contrast material in a delayed fashion (10 to 15 minutes after contrast administration), probably owing to a combination of increased vascular permeability and enlargement of the extracellular space. The percentage of the myocardial thickness showing delayed phase enhancement correlates inversely with the likelihood of return of function of that segment of myocardium after a revascularization procedure.