Atherosclerotic plaque characterization by 0.5-mm-slice multislice computed tomographic imaging - Comparison with intravascular ultrasound

Background: It has been proposed that 0.5-mm-slice multislice computed tomography (MSCT) is a noninvasive tool for the detection of atherosclerotic plaque, but the validity of such an assessment has not been demonstrated by an invasive investigation. The present study was performed to compare the 0.5-mm-slice MSCT density of plaques with intravascular ultrasound (IVUS) findings. Methods and Results: Atherosclerotic plaques were characterized in 37 consecutive patients undergoing percutaneous interventions. Based on the IVUS echogenecity, the plaques were classified as soft (n=18), fibrous (n=40) or calcified (n=40). In these 98 plaques, 0.5-mm-slice MSCT plaque density was calculated in 443 regions-of-interest, including 331 lesional foci and 112 luminal cross-sections, and represented as Hounsfield units (HU). MSCT density of the 3 types of plaque was 11±12 HU, 78±21 HU, and 516±198 HU respectively. Computed tomography density of the (contrast-filled) lumen was 258±43 HU. There were statistically highly significant differences in the densitometric characteristics among the 4 groups (soft, fibrous, calcified plaque and lumen) by nonparametric Kruskal-Wallis test (p<0.0001). Conclusions: The IVUS-based coronary plaque configuration can be accurately identified by 0.5-mm slice MSCT. Noninvasive assessment of plaque characterization will ensure emphasis on the vessel wall beyond the vascular lumen.