Abstract 3409: Monitoring of Changes in Atheroma Volume by 64-Slice Computed Tomography.

Abstract

Non-invasive assessment of plaque burden by Multislice Computed Tomography (MDCT) has been recently shown to be feasible. However, to date, there is no data on its accuracy to assess changes in atheroma burden We and others have previously shown that apoA-IMilano (apoA-IM) infusion induces a large plaque regression in a very short period of time The aim of our study was to assess the feasibility of MDCT to accurately quantify the changes in atheroma volume induced by apoA-IM infusion Methods Aortic atherosclerotic lesions were induced in New-Zealand-White Rabbits (n=7) by 9-month atherogenic diet and aortic denudation, as previously reported. Animals were then randomized to receive 2 infusions, 4 days apart, of apoA-IM (ETC-216, Pfizer. n=4) or equal volume of placebo (n=3). All animals underwent 2 imaging studies in a 64-Slice MDCT scanner (Sensation 64, Siemens), pre- and post-treatment (Rx). After last MDCT study, animals were sacrificed and the aorta processed for histological atherosclerotic lesions characterization and volume quantification . Axial MDCT images were reconstructed (3 mm thick, no overlap). Display settings were manipulated according to previous validated studies. For lumen delineation: window width (WW) 1 and level (WL) 65% of lumen attenuation . For outer vessel boundaries: WW 155% and WL 65%. Results MDCT showed that plaque burden regressed by 29% in apoA-IM group (418mm 3 pre-Rx vs. 302mm 3 post-Rx, p=0.031). Conversely, no significant change was observed by MDCT studies done pre- and post-placebo administration. MDCT performed post-Rx showed that mean plaque volume in apoA-IM animals was 11.5% smaller than that of placebo animals (p=0.018). Mean plaque volume in histology showed similar results:plaque volume was 10.6% smaller in the apoA-IM group (p=0.005 vs. placebo). The interobserver variability for plaque volume quantification in MDCT was 10±4%. Conclusion MDCT detects the changes in atherosclerotic plaque volume induced by apoA-IM infusion. Furthermore, an excellent correlation was found between MDCT and histological plaque volumes. These results, combined to the short time of scan and the accessibility to the coronary territory suggest that MDCT could be applied in human studies testing changes in coronary plaque volume.