Abstract 3083: How Reliable Are 40 MHz IVUS And 40-slice MDCT In Characterizing Coronary Plaque Composition ? A Histopathological Assessment
Background and Objectives: Plaque composition is a major determinant of coronary-related clinical syndromes. Multi-detector computed tomography (MDCT) enables visualization of atherosclerotic plaque but has been validated in only a few ex vivo studies. In vivo clinical studies, moreover, have assessed MDCT only against intravascular ultrasound (IVUS). The aim of the present ex vivo study was to assess the reliability of 40 MHz IVUS and 40-slice MDCT in differentiating human atherosclerotic coronary plaque components, against a histologic gold standard.
Materials and method: Specimens were postmortem right-coronary arteries. 54 coronary cross-sections were imaged by 40 MHz IVUS and by 40-slice MDCT. Atherosclerotic lesions were characterized histologically and classified as calcified, fibrous or lipid-rich plaque. The intra-plaque CT attenuation was measured in Hounsfield Units (HU) and the plaque composition was analyzed visually according to IVUS and MDCT criteria, and the correlation with histology were evaluated (sensitivity (Se), specificity (Sp), negative (npv) and positive (ppv) predictive value).
Results: 83 atherosclerotic plaques were identified. The mean CT attenuation was measured as 966 +/− 473 HU for calcified plaques (the highest, p<0.001), 83 +/− 35 HU for fibrous plaques and 70 +/− 41 HU for lipid-rich plaques. No significant difference in mean CT attenuation was found between fibrous and lipid-rich plaques (p<0.249).
Conclusion: 40 MHz IVUS produces acoustic ambiguities which may lead to errors of interpretation. 40-slice MDCT, in turn, fails to distinguish clearly between fibrous and lipid-rich plaques, in terms of both qualitative and CT attenuation factors. The components of atherosclerotic plaque are in fact frequently analyzed using MDCT, which is compared to IVUS as a reference technique. This means that the ambiguities inherent to both imaging techniques are being accumulated, making the assessment unreliable.