Noninvasive ultrasound techniques versus angiography for monitoring drug-induced changes of the arterial walls.

Even though angiographic studies contribute to understanding the process of atherosclerosis progression/regression in humans, they have several important limitations. The number of participants in all the studies is small and those who accept the invasive vascular investigation are highly selected patients, in most instances in an advanced stage of cardiovascular disease. Furthermore, arteriography provides the image of the vessel lumen but no information on the vessel wall. Noninvasive methods can describe the characteristics of the arteries with regard to morphology (intima-media thickness, surface irregularities, areas of calcification) and the hemodynamic correlates of vascular lesions. No single methodology describes all aspects of the disease process. However, B-mode ultrasound imaging gives information on the vessel wall, whereas Doppler mainly describes the hemodynamic consequences of arterial disease. Before any noninvasive methodology can be adopted for a clinical trial, extensive validation data (preferably using pathology rather than angiography as a "gold standard"), and accurate information on reproducibility and on inter-, intraobserver variability, should be available. Also, quantitative details on the natural history of the disease and on the potential of intervention, as evaluated by the specific methodology to be used, should be known.