Potential role of cardiovascular imaging in improving cardiovascular outcome in coronary artery disease

Background: There is increasing interest in cardiovascular imaging modalities in the detection of subclinical and clinically-manifested coronary artery disease (CAD) to improve cardiovascular outcome in these patients. Methods: SPECT/CT and PET/CT can be applied for the assessment of myocardial perfusion and myocardial blood flow (MBF) quantification in CAD detection and characterization, while CT is predominantly used to identify coronary plaque burden and epicardial narrowing. In addition, PET/CT plays an increasing role in the detection of the “vulnerable” plaque in the epicardial artery. Results: Imaging of myocardial perfusion with SPECT, SPECT/CT and PET/CT is a mainstay in clinical practice for the identification of flow-limiting epicardial lesions and risk stratification of patients with suspected or known CAD. In this direction, the concurrent ability of PET/CT to determine regional myocardial blood flow (MBF) in ml/g/min at rest and during pharmacologically-induced hyperemic flows allows the calculation of the myocardial flow reserve (MFR) that may unravel reductions in coronary vasodilator capacity, as functional precursor of the CAD process, monitor its response to preventive medical intervention, yield important prognostic information in subclinical-and clinically-manifested CAD, and contributes to identify the flow-limiting effect of single lesions in multivessel CAD. Adding noncontrast computed-tomography (CT) measurements of coronary artery calcifications has further improved the reclassification of cardiovascular risk in asymptomatic individuals with intermediate probability of the presence of CAD. With contrast CT, the non-invasive visualization of coronary vessels, CAD-related plaque burden and stenosis has become feasible. Yet, a definite identification of the “vulnerable plaque” is still a matter of ongoing research. PET/CT in conjunction with various positron-emitting radiotracer yields promise in the detection of the “vulnerable plaque,” that, however, needs further clinical evaluation in CAD patients. Conclusion: Multimodality imaging in cardiovascular disease is likely to further advances and refine the identification and characterization of cardiovascular pathology in the near future.