Plaque quantification by coronary CT and intravascular ultrasound identifies a low CT density core as a marker of plaque instability in acute coronary syndromes.

The purpose of this study was to demonstrate the relationship between the presence and amount of a low-density core (LDC) with a CT density < 30 Hounsfield units (HU) by coronary computed tomography angiography (CCTA) and IVUS-derived markers of vulnerability in the culprit lesions (CL) of patients with acute coronary syndromes (ACS).In 43 patients with ACS, 105 coronary plaques were scanned using CCTA and IVUS for the quantitative and qualitative assessment of vulnerability markers.The presence of a low attenuation plaque (LAP) was identified in 67.4% of the CL and 29.03% of the non-CL (P = 0.0001). The presence of a LDC > 6.0 mm(3) was significantly correlated with the percentage of the necrotic core (NC) (22.08% versus 7.97%, P = 0.001) and the fibro-fatty tissue by IVUS (18.68% versus 15.87%, P = 0.02). LDC volumes showed a good correlation with the percentage of the NC (r = 0.7303, P < 0.0001) and the fibro-fatty tissue in the CL (r = 0.4928, P < 0.0008). Quantitative plaque analysis revealed a significant difference in plaque composition between CL and non-CL in regards to the LDC (18.45 versus 6.5, P < 0.001), the percentage of NC (20.74 versus 18.74, P = 0.02), fibro-fatty tissue (17.77 versus 15.48, P = 0.002), and fibrotic tissue (51.68 versus 54.8, P = 0.01).VH-IVUS and CCTA plaque quantification showed that the presence of a low-density (< 30 HU) core within the CL of patients with ACS represents a marker of vulnerability and correlates well with other CCTA and IVUS-derived features of vulnerability, particularly the NC of the plaque.