Quantification of myocardial perfusion and myocardial perfusion reserve by positron emission tomography and cardiovascular magnetic resonance imaging.

Physiology and pathophysiology of myocardial perfusion regulation and of myocardial perfusion reserve. Because of the high energy demands of myocardial contraction, the heart is critically dependent on oxidative metabolism, and insufficient myocardial oxygen delivery (i.e., ischemia) results almost instantaneously in contractile and electrical dysfunction. Because myocardial oxygen extraction in the blood is already near maximal under resting conditions, myocardial perfusion is strongly correlated with myocardial oxygen consumption, and the principal mechanism for increasing oxygen delivery to the heart is by increasing myocardial perfusion (1).