Abstract 214: Assessment of Coronary Atherosclerotic Plaque by High-Definition Computed Tomography: An ex vivo Study in Human Hearts
Background: Although advanced multi-detector CT permits non-invasive visualization of the coronary atherosclerotic plaque, characterization of histologic features of plaques has not been established. We determined the ability of high definition CT (HDCT) to differentiate distinct histologic appearance of calcification and fibrous plaque content in advanced and early atherosclerotic lesions.
Method: Coronary arteries of four human donor hearts with history of coronary artery disease were filled with a methylcellulose based iodinated contrast solution. The hearts were imaged by HDCT (GE HD750CT, in plane resolution of 230 microns). CT cross-sections of the coronaries were reconstructed with a 0.5 mm slice thickness and consecutively co-registered in every 5 mm to histological sections. The relative calcified, fibrous and lipid content of each CT cross section was measured (defined as lipid −150 to 30 HU, fibrous 31 to 130 HU and calcified above 130 HU) and compared to the histological classification of calcium appearance (micro, spotty, sheet) and plaque stage (early: adaptive and pathological intimal thickening, fibrous plaque; advanced: early and late fibroatheroma, thin cap fibroatheroma), respectively.
Results: Among 136 cross sections, any calcification was determined by histology in 46 (33%) slices. These were further sub classified into ‘micro’ (n=29), ‘spotty’ (n=10) and ‘sheet’ (n=10). The portion of calcified plaque as determined by HDCT were significant different within histology strata of calcification (p=0.0002), with 4.17% (95% CI: 1.87 – 6.48%) for micro, 9.45% (95% CI: 4.11 – 14.79%) for spotty and 21.41% (95% CI: 14.75 – 28.08%) for sheet calcification. Furthermore, the relative amount of fibrous tissue as measured on HDCT slices was significantly higher in early as compared to advanced coronary plaques: 86.00% (95% CI: 84.41– 87.59%) vs. 80.19% (95% CI: 75.61– 84.76), p=0.007, respectively.
Conclusion: Relative content of calcified and fibrous plaque tissue correlate with histological classification of calcification and plaque stage. Further research is warranted to determine whether HDCT may provide more detailed characterization of coronary plaque, potentially enabling assessment of vulnerability.