COMPUTERIZED ASSESSMENT OF CORONARY LUMEN AND ATHEROSCLEROTIC PLAQUE DIMENSIONS IN 3-DIMENSIONAL INTRAVASCULAR ULTRASOUND CORRELATED WITH HISTOMORPHOMETRY

Intravascular ultrasound (IVUS), which depicts both lumen and plaque, offers the potential to improve on the limitations of angiography for the assessment of the natural history of atherosclerosis and progressi on or regression of the disease. To facilitate measurements and increa se the reproducibility of quantitative IVUS analyses, a computerized c ontour detection system was developed that detects both the luminal an d external vessel boundaries in 3-dimensional sets of IVUS images. To validate this system, atherosclerotic human coronary segments (n=13) w ith an area obstruction greater than or equal to 40% (40% to 61%) were studied in vitro by IVUS. The computerized IVUS measurements (areas a nd volumes) of the lumen, total vessel, plague-media complex, and perc ent obstruction were compared with findings by manual tracing of the I VUS images and of the corresponding histologic cross sections obtained at 2-mm increments (n=100). Both area and volume measurements by the contour detection system agreed well with the results obtained by manu al tracing, showing low mean between-method differences (-3.7% to 0.3% ) with SDs not exceeding 6% and high correlation coefficients (r=0.97 to 0.99). Measurements of the lumen, total vessel, plague-media comple x, and percent obstruction by the contour detection system correlated well with histomorphometry of areas (r=0.94, 0.88, 0.80, and 0.88) and volumes (r=0.98, 0.91, 0.83, and 0.91). Systematic differences betwee n the results by the contour detection system and histomorphometry (29 %, 13%, -9%, and -22%, respectively) were found, most likely resulting from shrinkage during tissue fixation. The results of this study indi cate that this computerized NUS analysis system is reliable far the as sessment of coronary atherosclerosis in vivo. (C) 1996 by Excerpta Med ica, Inc.