An evaluation of methods for imaging and quantifying coronary and carotid lumen stenosis and atherosclerosis

Methods for imaging arterial disease manifest by compromise of the lumen or thickening of the walls are undergoing continuing development and refinement. Methods used for many years to image arterial lumens (e.g., angiography, Doppler ultrasound) are of greatest utility for assessing the relation of arterial disease to clinical outcome. Newer methods (B-mode ultrasound) visualize arterial walls and thus provide qualitatively different information that has not previously been available to investigators and that is particularly suitable for studies of the relation of risk factors to arterial disease.

Methodology for imaging arterial lumens considerably antedates that for imaging walls, adequately describes severe stenosis, is relevant to the relation of arterial disease to clinical outcome, and is sufficiently reliable to support clinical trials. Angiographic morphology is increasingly recognized as an important contributor to disease outcome. However, despite developments in imaging (e.g., quantitative coronary angiography), validity is poor for identification of early disease or advanced disease of the wall of the artery that does not obstruct the lumen. B-mode ultrasound is a newer method for imaging arterial disease that provides reliable and valid estimates of early disease of arterial walls. Such minimally obstructive disease may be clinically relevant, and quantification of disease of the arterial wall permits the investigator to develop normative data for wall thickness and to explore precise dose-response relations between risk factors and extent of disease. Only invasive methods are available for imaging the coronary arteries, whereas both invasive and noninvasive methods are suitable for imaging extracranial carotid and ileofemoral arteries. Noninvasive (B-mode, Doppler) imaging of arteries affords the opportunity to carry out cross-sectional studies, cohort studies, and clinical trials with far less bias than studies relying on invasive imaging.

Methods of imaging lumen stenosis complement those that image the arterial wall and provide different information. The development of new, safe, low-cost, noninvasive methods that can quantify early atherosclerosis of peripheral arteries has resulted in a broad range of opportunities for epidemiological studies. The choice of method should be governed by the experimental design and question to be answered.