Multi-detector CT (MDCT) permits non-invasive visualization of the coronary arteries. Coronary plaque can be visualized, and earlier studies have indicated that the CT attenuation measured in atherosclerotic plaques is influenced by plaque composition. Also, MDCT has been shown to permit assessment of remodeling of coronary atherosclerotic lesions. It is assumed that both lipid-rich plaques and those that display positive remodeling are more prone to rupture and erosion. We thus evaluated the relationship between remodeling and CT attenuation of coronary atherosclerotic plaque by MDCT.
Methods: Seventy-six patients were investigated by contrast-enhanced 64-slice CT. One-hundred twelve atherosclerotic lesions without substantial calcification and visualized with high image quality were selected. Multiplanar reconstructions orthogonal to the coronary artery were rendered at the lesion and the proximal reference site. Cross-sectional vessel areas were measured to determine the remodeling index (RI: lesion vessel area/reference vessel area) and the CT attenuation of plaque was measured by fitting a region of interest to the plaque area. CT attenuation of plaque was correlated to the presence of positive remodeling index (RI>1.05).
Results: The mean cross-sectional vessel area in the lesion was 0.25+/-0.08 cm(2), the mean reference vessel area was 0.22+/-0.09 cm(2). The mean CT attenuation of the atherosclerotic plaque in the lesions was 71+/-26 HU. CT attenuation of plaque was significantly lower in 72 lesions that displayed positive remodeling (59+/-22 HU) than in 40 lesions with no or with negative remodeling (91+/-20 HU, p<0.001).
Conclusions: Positive remodeling of coronary atherosclerotic lesions correlates to lower CT attenuation of plaque, which has been demonstrated to be associated with lipid-rich plaque. Both characteristics indicate increased risk for plaque rupture and subsequent events and could thus prove useful when the use of CT imaging for the detection of "vulnerable plaque" is considered.