Clinical applications of cardiac positron emission tomography (PET) have made dramatic advances over the past three years, particularly in myocardial perfusion imaging. These advances include cardiac-specific PET technology, specialized software, and profound biological insights into myocardial perfusion far beyond the traditional binary interpretation of perfusion images as normal or abnormal requiring arteriorgaphic confirmation.
The advances in cardiac PET also interact powerfully with documentation that vigorous pharmacologic and lifestyle management stabilize plaque, partially reverse coronary artery disease (CAD), and decrease cardiac events by 90% at long-term follow-up. While not widely recognized, cardiac PET-including PET-computed tomography (CT), has been demonstrated to be the single most powerful non-invasive tool for the integrated tasks of identifying early coronary artery stenosis or diffuse disease, assessing severity of stenosis, objectively determining need for revascularization procedures, following progression or regression of disease, and directly evaluating endothelial function of the coronary arteries as a marker of early atherosclerosis.
The integration of diagnostic imaging with intense medical treatment as a combined subspecialty service has catapulted cardiac PET treatment programs into the same conceptual category as diagnostic theraputic invasive cardiology. This article outlines these scientific advances that are now routinely applicable for physicians and patients who recognize and wish to pursue this approach to the management of CAD.
Precise Myocardial Perfusion Anatomy
Myocardial perfusion images by PET are acquired in tomographic slices corrected for attenuation loss, random coincidences, scattered radiation, dead time losses, and variation in detector sensitivity. The tomographic data is rotated into true long and short axis views and compiled or stacked into a quantitative three-dimensional (3-D) topographic display of cardiac activity as a thin shell in the shape of the left ventricle displaying the normalized maximum activity across the left ventricular (LV) wall. Four views of the heart are displayed at 90┬║ angles as if walking around the heart from left lateral to inferior to right lateral (septal) to anterior views. The activity is normalized to the top 2% of activity in the whole heart data set and scaled from the maximum of 100% in white with stepped downward increments to red, yellow, green, blue, and black being progressively more severe defects as in the PET perfusion images of Figure 1.