Abstract 9410: Quantification and Characterization of Noncalcified Coronary Plaque by High Definition Computed Tomography : Comparison with Integrated Backscatter Intravascular Ultrasound

Abstract

Background: Noninvasive assessment of coronary plaque is important for coronary risk stratification. The utility of 64-slice CT remains unclear for evaluation of coronary plaque component. Recently high definition computed tomography (HDCT) with new gemstone detector has been developed, which has high spatial resolution. We evaluated the accuracy of HDCT for quantification and characterization of noncalcified coronary plaque compared with integrated backscatter intravascular ultrasound (IB-IVUS).

Methods: We enrolled consecutive 33 patients with unstable or stable angina. Noncalcified plaque of target lesion was evaluated by HDCT and the findings were compared with those of IB-IVUS at the same sites. Plaque was classified as lipid (-42 to 60 HU: Hounsfield unit), fibrous (61 to 112 HU) or calcified (>500 HU) by HDCT and we evaluated minimum lumen area (MLA), percentage of stenosis (%stenosis), total plaque volume, lipid volume, percentage of lipid volume (%lipid), fibrous volume and percentage of fibrous volume (%fibrous).

Results: A total 38 noncalcified coronary plaques were evaluated. HDCT was well correlated with IB-IVUS for assessing MLA (2.53 ± 0.89mm vs. 2.62 ± 0.71mm, r=0.658, P<0.001), %stenosis (65.6 ± 12.4% vs. 63.5 ± 12.9%, r=0.870, P<0.001), plaque volume (156.2 ± 87.8mm³ vs. 144.0 ± 100.6mm³, r=0.886, P<0.001), lipid volume (86.1 ± 52.7mm³ vs. 76.5 ± 65.0mm³, r=0.901, P<0.001), %lipid (53.7 ± 10.6% vs. 49.8 ± 12.2%, r=0.570, P<0.001), fibrous volume (56.2 ± 25.6mm³ vs. 57.5 ± 35.8mm³, r=0.761, P<0.001) and %fibrous (38.7 ± 11.0% vs. 42.4 ± 10.0%, r=0.747, P<0.001).

Conclusion: HDCT with new gemstone detector can accurately quantify and characterize noncalcified coronary plaque compared with IB-IVUS. HDCT can be a useful tool for noninvasive assessment of vulnerable plaque.