Diagnostic procedures to image atherosclerosis

Abstract

Most cardiovascular events are pathogenically linked to atherosclerosis and they are one of the leading public health threat in most countries. Atherosclerotic plaques begin early in life and prevention of their progression toward clinical symptoms and signs require an early detection. Several different diagnostic strategies are available to identify direct and indirect signs of atherosclerosis. Among others, magnetic resonance imaging has the ability to image any body components at an almost molecular level. But it is costly and the level of its current resolution still poses limitations to its full application in vascular medicine. Ultrafast computed tomography has lately been used to screen high risk subjects by detecting coronary artery calcifications. However, available data are not sufficient to draw any realistic conclusion about its applicability and diagnostic value. Arteriography can provide information on the lumen characteristics of any artery independently from its size, location or morphological status. Its main application rests in the study of the coronary circulation, and the main advantage is the close relationship between coronary status and coronary ischemia. Quantitative Coronary Angiography (QCA) protocols are available and used for clinical and research applications. QCA provides accurate and precise estimates of lumen stenosis at discrete points of the coronary tree by using sophisticated imaging work stations. However, arteriography is invasive, therefore it cannot be used to study high risk, but still asymptomatic subjects. Furthermore, while providing well defined images of the arterial lumen, the arterial wall is not imaged, and it has been shown that arteriography may underestimate the severity of small lesions. B-mode ultrasound imaging overcomes some of the limitations carried by angiography. It is non-invasive, and can be used to examine repeatedly asymptomatic subjects. It provides multiple views of the lumen and the wall. However, B-mode can be used only to image large and superficial arteries (carotid and femoral), and it may underestimate large and/or complicated plaques. B-mode is a valid and reproducible method to image the arterial wall and to measure the arterial intima-media thickness. Based on experimental work, B-mode protocols have been used to study the arterial wall morphology both in epidemiological investigations and interventional clinical trials.