Clinical Application of Myocardial Blood Flow Quantification in CAD Patients

With the introduction of the concurrent myocardial blood flow (MBF) quantification in ml/g/min with positron emission tomography/computed tomography (PET/CT) assessment of myocardial perfusion in clinical routine, the scope of conventional scintigraphic myocardial perfusion imaging now expands from the identification of the most advanced and culprit CAD lesion, as signified by the stress-induced regional myocardial perfusion defect, also to less severe but flow-limiting stenosis in multivessel CAD. Thus, by adding regional MBFs determined at rest and during vasomotor stress with the resulting myocardial flow reserve (MFR=MBF during stress/MBF at rest) to conventional myocardial perfusion PET/CT, a comprehensive identification and characterization of flowlimiting effects of multivessel CAD has become feasible. The non-specific nature of the hyperemic MBF increase and MFR, however, necessitates an evaluation and interpretation of regional hyperemic MBFs in the appropriate context with coronary morphology, microvascular function, and wall motion analysis in patients with CAD. Such a diagnostic approach may foster a more individualized and image-guided decision making process towards coronary revascularization procedures in patients with complex multivessel CAD that, however, remains to be tested in clinical outcome studies.