Flat-Panel Computed Tomography for Longitudinal Assessment of Atherosclerotic Plaque Components: Quantitative Correlations with Pathologic Measurements
Ibrahim Aboshady, Dianna D Cody, Evan M Johnson, Deborah Vela, Kamal G Khalil, Gregory W Gladish, L Maximilian Bula. The Texas Heart Institute, Houston, TX; M.D. Anderson Cancer Center, Houston, TX; The University of Texas HSC, Houston, TX; Baylor College of Medicine, Houston, TX
Background: Flat-panel computed tomography (FpCT) provides better spatial resolution than 64-channel CT and better assesses atherosclerotic plaque components in vivo in animal aortas similar in size to human coronary arteries. We assessed the usefulness of FpCT in longitudinal studies of plaque development.
Design: We used a prototype FpCT scanner with a dual-panel rotating gantry and a commercial Performix CT x-ray source. 184 aortic histology sections from 6 Watanabe heritable hyperlipidemic rabbits were quantitatively compared with 64-CT (image thickness, 0.625 mm) and FpCT (image thickness, 0.150 mm) images. Images were reoriented perpendicular to the vessel centerline.
Results: Although FpCT was more sensitive in detecting eccentric lesions (42% vs 0%; P=0.000), the area under the curve (AUC) for FpCT (0.6) did not significantly differ from that for 64-CT (0.45; P=NS). In detecting plaques with ≤10% lipid (low-attenuation foci), FpCT was more sensitive than 64-CT (24% vs 0.7%; P<0.00) and had a greater AUC (0.6 vs 0.5; P<0.006). Additionally, FpCT was more sensitive (65% vs 0%; P<0.00) in detecting plaques with ≤5% calcium (high-attenuation foci) but not in detecting branch points. Both FpCT and histology could detect low-attenuation foci as small as 0.3 mm in diameter, whereas 64-CT could detect only low-attenuation foci ≥1.5 mm in diameter. In the current, long-term phase of the study, 30 New Zealand White hyperlipidemic rabbits receive a high-fat diet (0.5% cholesterol). Lesions are monitored and correlated through monthly serial scanning sessions over 6 months. Images are collected 30 seconds after Visipaque injection (560 mgI/kg; through an ear vein).
Conclusions: FpCT seems to have more potential in quantitative screening for low-risk small atherosclerotic lesions, whereas 64-CT is limited to imaging established, well-characterized lesions, particularly when measuring the vascular wall thickness in a rabbit model of atherosclerosis. FpCT seems to have potential for quantitatively monitoring the evolution of the calcific and lipid components of plaque.
Wednesday, March 21, 2012 1:00 PM
Poster Session VI # 47, Wednesday Afternoon