IMPACT OF CONTOUR-DETECTION ON THE ASSESSMENT OF QUALITATIVE VESSEL WALL CHARACTERISTICS BY INTRACORONARY ULTRASOUND AFTER EXPERIMENTAL BALLOON ANGIOPLASTY

Percutaneous transluminal coronary angioplasty (PTCA) ultimately resul ts in complex changes in the morphology of the treated vessel, which m ay be reflected better by cross-sectional intracoronary ultrasound (IC US) than by silhouette imaging techniques (angiography). Frequently, h owever, for ICUS an optimal imaging quality cannot be achieved after P TCA in vivo. To investigate the diagnostic value of ICUS in vessels wi th a suboptimal imaging quality after PTCA, we examined 217 segments o f 21 isolated coronary arteries, comparing the images of a mechanical ICUS device (30 MHz, 4.5F) with the corresponding histologic specimens after balloon angioplasty. The sensitivity and specificity of ICUS in the detection of intimal thickening (>0.5 mm), plaques, or dissection s were assessed for subgroups with higher (group I) and lower (group I I) imaging quality. In 20.8% of all segments, borders of lumen and adv entitia could be visualized along at least at 75% of the circumference (group I); this was not possible in smaller vessels (diameter < 2.5 m m; p< 0.001). The sensitivity of ultrasound for the detection of intim al hyperplasia was higher (p < 0.05) in group I (100%, n = 10) compare d with group II (67.3%, n = 33), whereas specificity was similar (I 97 .8%, II 93.8%). Sensitivity and specificity were comparable for the de tection of plaques (I 83.3%, II 87.5%; I 91.9%, II 93.3%). Detection o f dissections was also possible in 90.9 and 87.9%, respectively, in gr oups I and II (specificity I 95.5%, II 96.1%). Thus, imaging quality i s significantly lower in smaller vessels. The detection of intimal thi ckening in particular is restricted to vessels with a high imaging qua lity. In contrast, our data suggest a high sensitivity and specificity of ICUS for detection of plaques and dissections, even if imaging qua lity is reduced after PTCA.