VARIABILITY IN THE MEASUREMENT OF INTRACORONARY ULTRASOUND IMAGES - IMPLICATIONS FOR THE IDENTIFICATION OF ATHEROSCLEROTIC PLAQUE REGRESSION

Background and hypothesis: Serial coronary angiography cannot reliably detect the small changes in arterial dimensions. Measurement of arter ial dimensions by intracoronary ultrasound (ICUS) may be a superior me thod to determine the extent of atherosclerotic burden since it direct ly images the diseased portion of the vessel. Methods: To quantify int er- and intraobserver variability of ICUS measurements, 27 images of a therosclerotic coronary lesions were measured by two study physicians and repeated 14 days later. Results: Interobserver correlation coeffic ients for external elastic lamina, lumen, and effective plaque area we re 0.96, 0.99, and 0.91, respectively. Intraobserver correlation coeff icients for external elastic lamina, lumen, and effective plaque area were 0.99, 0.99, and 0.97, respectively. To determine progression or r egression in effective plaque area, a minimal difference of 2.77 mm(2) (which represents a 23% change in plaque area) is needed. Conclusions : Direct visualization of the extent of atherosclerosis by ICUS can be accomplished with a low degree of inter- and intraobserver variabilit y. ICUS may be a preferable alternative to angiography in atherosclero sis regression trials.