[318] Preclinical Evaluation of Plaque Morphology and Development by Flat-Panel Computed Tomography

Ibrahim Aboshady, L Maximilian Buja. Texas Heart Institute, Houston, TX; University of Texas HSC, Houston, TX

Background: Current multidetector computed tomography (MDCT) imaging of plaque components within lesions will require additional improvement to the instrumentation in order to accurately predict their vulnerability. We have previously shown in an acute pilot study that Flat-panel computed tomography (FpCT) provides better spatial resolution than 64-MDCT and better assesses plaque components in vivo in animal aortas similar in size to human coronary arteries. In this phase, we quantitatively evaluated the maximum capabilities and limitations of FpCT in longitudinal studies of plaque development as correlated to histopathology as a gold standard.
Design: The commercially available amorphous silicon fluoroscopic FpCT x-ray detectors offer 200µ native resolution. With an automated tool; multiplanar reformatted images were created perpendicular to the center line of the aorta along its entire imaged length. Lesions in 184 aortic histology sections from 6 WHHL rabbits and 30 NZW hyperlipidemic rabbits were quantitatively compared with 64-CT (image thickness, 0.625 mm) and FpCT (image thickness, 0.150 mm) images. In the long-term phase of the study, rabbits received a high-fat diet (0.5% cholesterol) and angiotensin II (0.4 μg kg1 min1 , through SC osmotic pumps) for 6 months. Lesions are monitored and correlated through monthly serial scanning sessions over 6 months.
Results: FpCT was more sensitive in detecting eccentric lesions (42% vs. 0%; P=0.000). 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, whereas 64-CT could detect only low-attenuation foci ≥1.5 mm in diameter. Of the 48 lesions classified to AHA criteria as type II by histology, 42 were also classified as type II by FpCT and 35 by 64-CT. FpCT was significantly more sensitive than 64-CT in detecting all types.
Conclusions: The study confirms our pilot study data that FpCT seems to have more potential in quantitative screening for low-risk small atherosclerotic lesions than MDCT in a rabbit model of atherosclerosis. FpCT have also the capacity for quantitatively assessment the development of calcific and lipid components of atherosclerotic plaque.
Category: Cardiovascular

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 48, Wednesday Morning

 

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