Atherosclerosis is a condition in which fatty material like cholesterol aggregates and hardens to form calcium deposits along the walls of arteries which leads to blockage of arteries. The fat and calcium deposits together form plaque in the arteries. In this condition the arteries become narrow which slows down blood flow to the heart which may result in chest pain, heart attack and shortness of breath.

The assessment of atherosclerosis can be done by a number of invasive and noninvasive imaging techniques such as X-ray angiography, CT, Intravascular ultrasound(IVUS), MR imaging, Position emission tomography (PET) to detect and display different characteristics of vascular lesions. X-ray angiography is the standard imaging technique used but it fails to detect atherosclerotic lesions and provides less information on atherosclerotic plaque composition which is unable to predict the risk of plaque rupture. Intravascular ultrasound (IVUS) provides imaging of atheroma and gives a 2D cross-sectional image of the entire plaque and vessel wall but IVUS is invasive and requires more time, expertise, and expensive. CT and MRI can be used to detect flow-limiting lesions in the proximal coronary arteries. Specifically Electron beam CT can quantify the calcium. Both CT and MRI are limited to anatomical data, functional imaging is not possible. PET and SPECT are advanced imaging techniques which provide information on cell biologic events that determine risk of plaque rupture.