title: Intravascular ultrasound area strain imaging used to characterize tissue components and assess vulnerability of atherosclerotic plaques in a rabbit model.
abstract: The purpose of this study was to investigate the association of area strain and tissue components and vulnerability of atherosclerotic plaques in a rabbit model. Forty purebred New Zealand rabbits underwent balloon-induced abdominal aorta endothelium injury, then a high-cholesterol diet for 24 weeks. Intravascular ultrasound (IVUS) images of abdominal aortas were acquired in situ and two consecutive frames near the end-diastole were used to construct an IVUS elastogram. Histologic slices matched with corresponding IVUS images were stained for fatty and collagen components, smooth muscle cells (SMCs) and macrophages. Regions-of-interest (ROIs) in plaques were classified as fibrous, fibro-fatty or fatty according to histologic study. Vulnerability indexes of ROIs were calculated as (fat + macrophage)/(collagen + SMCs). The area strain of these ROIs was calculated by use of an in-house-designed software system with a block-matching-based algorithm. Area strain was significantly higher in fatty ROIs (0.056 ± 0.003) than in fibrous (0.019 ± 0.002, p < 0.001) or fibro-fatty ROIs (0.033 ± 0.003, p < 0.001). The sensitivity and specificity of area strain for fatty ROIs characterization was 75.0% and 80.2% (area under the curve [AUC] 0.858, 95% confidence interval [CI] = 0.800-0.916, p < 0.001) and 75.0% and 75.3% (AUC 0.859, 95% CI = 0.801-0.917, p < 0.001) for fibrous ROIs, as demonstrated by receiver operating characteristic curve analysis. Area strain was positively correlated with vulnerability index (r(2) = 0.495, p < 0.001), fatty components (r(2) = 0.332, p < 0.001) and macrophage infiltration (r(2) = 0.406, p < 0.001); and negatively correlated with collagen and SMC composition (r(2) = 0.115 and r(2) = 0.169, p < 0.001, respectively). Area strain calculation with IVUS elastography based on digital B-mode analysis is feasible and can be useful for tissue characterization and plaque vulnerability assessment.
authors.affiliation: The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Qilu Hospital of Shandong University, Jinan, China.
authors.forename: Xiao-Bo
authors.initials: XB
authors.lastname: Hu
authors.forename: Peng-Fei
authors.initials: PF
authors.lastname: Zhang
authors.forename: Hai-Jun
authors.initials: HJ
authors.lastname: Su
authors.forename: Xin
authors.initials: X
authors.lastname: Yi
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.forename: Yuan-Yuan
authors.initials: YY
authors.lastname: Rong
authors.forename: Ke
authors.initials: K
authors.lastname: Zhang
authors.forename: Xuan
authors.initials: X
authors.lastname: Li
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.forename: Chun-Li
authors.initials: CL
authors.lastname: Sun
authors.forename: Xiao-Jun
authors.initials: XJ
authors.lastname: Cai
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Jian-Tao
authors.initials: JT
authors.lastname: Song
authors.forename: Xiao-Min
authors.initials: XM
authors.lastname: Dai
authors.forename: Xiao-Di
authors.initials: XD
authors.lastname: Sui
authors.forename: Yun
authors.initials: Y
authors.lastname: Zhang
authors.forename: Mei
authors.initials: M
authors.lastname: Zhang
mesh_terms: D000465:Algorithms; D000704:Analysis of Variance; D000818:Animals; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging* / Q000473:pathology; D004195:Disease Models, Animal; D004562:Electrocardiography; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008264:Macrophages / Q000473:pathology; D008297:Male; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging* / Q000473:pathology; D012372:ROC Curve; D011817:Rabbits; D012680:Sensitivity and Specificity; D014463:Ultrasonography