QUANTIFICATION OF REGIONAL MYOCARDIAL PERFUSION BY PET - RATIONALE AND FIRST CLINICAL-RESULTS

With the recent advances in interventional cardiology there is increas ing need for characterization of the functional effects of coronary ar tery stenosis. Stress echocardiography and SPECT perfusion imaging are standard techniques for the qualitative assessment of regional functi on and perfusion in patients with proven or suspected coronary artery disease. However; Positron emission tomography (PET) provides quantita tive measurements of regional myocardial perfusion. In combination wit h pharmacological stress testing, relative and absolute coronsry reser ve measurements can be used to define functional significance of regio nal coronary artery disease. First clinical results indicate that ther e is an overall agreement between angiographic and functional disease severity. However, there is a relatively large scatter of coronary res erve flow in patients with 50-90% coronary artery stcnosis, which emph asizes the complimentary role of perfusion imaging in the prediction o f functional severity. In addition, first studies in asymptomatic pati ents with a high risk for coronary artery disease suggest that PET cor onary reserve flow measurements be more sensitive than angiographic cr iteria for detection of early alterations in coronary vascular reactiv ity. Absolute quantification of blood flow may be useful in disease pr ocesses which affect the entire left ventricle such as vasculopathy in cardiac transplants, as well as endothelial dysfunction in patients w ith hypertension and cardiomyopathy. Future studies have to demonstrat e the prognostic value of the quantitative estimate of coronary reserv e as regards clinical outcome in patients with various coronary abnorm alities. Quantitative flow measurements will be useful for monitoring progression and regression of coronary artery disease as well as asses sment of acute and chronic therapy.