Non-invasive Fractional Flow Reserve CT (FFRCT)Scan for the Study of Coronary Vaso-motion

Cardiovascular disease is the leading cause of death in Singapore, and accounts for 31.9% of all deaths in 2010. Coronary vascular dysfunction has been linked to the development of cardiovascular-related events, such as death, myocardial infarction (MI), stroke and unstable angina. Recently, impaired coronary vaso-motion has been suggested as an independent predictor of poor prognosis, which can predict cardiovascular events in patients with epicardial Coronary Artery Disease . Coronary vaso-motion refers to the change in diameter of a coronary vessel in response to vasoactive agent, which is measured via quantitative coronary angiography (QCA). Better coronary vaso-motion response has been associated with improved survival for both obstructive and non-obstructive CAD. Another widely used invasive clinical imaging technology to assess CAD is intravascular ultrasound (IVUS), which uses ultrasound technology for imaging the endothelium of vessels. Since detailed histological information of plaques on the endothelium of coronary arteries can be provided by IVUS, it is used as gold standard in evaluating progression or regression of plaque. Although coronary vaso-motion, FFR and IVUS have been shown to improve clinical outcomes and procedural cost-efficiency in terms of guiding percutaneous interventions, they are invasive procedures. Non-invasive option for the diagnosis of myocardial ischemia is required to relief the patients' pain and medical cost due to the invasive cath. This study aims to fill in the gap. The investigators hypothesize that non-invasive FFRCT can be obtained by combining CT images and CFD methods, which can be used to assess the physiologic significance of CAD.