Assessment of tissue characteristics of noncalcified coronary plaques by 64-slice computed tomography in comparison with integrated backscatter intravascular ultrasound

Background: The ability of 64-slice computed tomography (CT) angiography to differentiate plaque types remains unclear. We evaluated whether the density of noncalcified coronary plaques by 64-slice CT angiography correlates with plaque components assessed by integrated backscatter intravascular ultrasound (IB-IVUS). Methods: Eighty-six patients [stable angina/acute coronary syndrome (ACS) 67/19, mean age 62±11 years] who showed significant coronary artery stenosis (≥ 50% diameter stenosis) by 64-slice CT angiography underwent coronary angiography and were evaluated using IB-IVUS. Results: A total of 92 noncalcified coronary plaques on CT angiography were evaluated with IB-IVUS. There was a positive correlation between CT density and calcified tissue content (r=0.41, P<0.001). However, the CT density of plaques did not correlate with other tissue components. Patients with ACS showed more lipid (43.1±13.2 vs. 35.8±13.5, P=0.03) and less soft fibrous tissue (50.5±11.7 vs. 56.5±12.0, P=0.05) by IB-IVUS than those with stable angina. However, the mean CT density of plaques in ACS was not different from that in stable angina (140.6±88.5 vs. 113.1±80.9, P=0.19). Conclusion: Except for calcified tissue, CT angiography failed to differentiate plaque types of noncalcified tissue. Therefore, the role of 64-slice CT angiography in identifying lipid-rich plaques remains limited.