title: Atherosclerotic plaque components characterization and macrophage infiltration identification by intravascular ultrasound elastography based on b-mode analysis: validation in vivo.
abstract: Intravascular ultrasound elastography (IVUSE) is a promising imaging technique for early investigation of vulnerable plaques. Compared to radiofrequency signal processing, digital B-mode analysis is simple and of higher portability. However, rare studies have been reported validating the latter technique in vivo. In this study, we developed an IVUSE computer software system involving semi-automatic border delineation and block-matching algorithm and validated the system in vivo. Seven minipigs were fed with atherogenic diet for 40 weeks. For each pig, the endothelium of one side of the renal arteries was denuded at the fifth week. With cross-correlation analysis, Lagrangian strain was calculated from two intravascular ultrasound images acquired in situ. Sixty regions of interests were selected from 35 elastograms matched well with the corresponding histological slices. Plaque types within these regions were classified as fibrous, fibro-fatty or fatty on Masson's trichrome and Oil-red O staining. Macrophage infiltration was also evaluated with immunohistology. Comparison between the mean strain value of the region of interest and the histological results revealed significant differences in strain values among different plaque types and non-diseased artery walls. The extent of macrophage infiltration was found to be correlated positively with strain values. For identification of fibro-fatty and fibrous plaques and macrophage infiltration, the system showed high sensitivity (93, 96 and 92%, respectively) and specificity (89, 76 and 66%, respectively), as revealed by receiver operating characteristic analysis. Our IVUSE system based on B-mode analysis is capable of characterizing fibrous and fibro-fatty plaques and macrophage intensity, thus holds potential for identifying vulnerable plaque.
authors.affiliation: The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Shandong University Qilu Hospital, Jinan, Shandong, 250012, China.
authors.forename: Peng-Fei
authors.initials: PF
authors.lastname: Zhang
authors.forename: Hai-Jun
authors.initials: HJ
authors.lastname: Su
authors.forename: Mei
authors.initials: M
authors.lastname: Zhang
authors.forename: Ji-Fu
authors.initials: JF
authors.lastname: Li
authors.forename: Chun-Xi
authors.initials: CX
authors.lastname: Liu
authors.forename: Shi-Fang
authors.initials: SF
authors.lastname: Ding
authors.forename: Ya
authors.initials: Y
authors.lastname: Miao
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.forename: Xiao-Nan
authors.initials: XN
authors.lastname: Li
authors.forename: Xin
authors.initials: X
authors.lastname: Yi
authors.forename: Yun
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000465:Algorithms; D000818:Animals; D050197:Atherosclerosis / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D054459:Elasticity Imaging Techniques; D005355:Fibrosis; D007090:Image Interpretation, Computer-Assisted; D007150:Immunohistochemistry; D008055:Lipids / Q000032:analysis; D008264:Macrophages / Q000737:chemistry / Q000000981:diagnostic imaging* / Q000473:pathology; D011237:Predictive Value of Tests; D012077:Renal Artery / Q000737:chemistry / Q000000981:diagnostic imaging* / Q000473:pathology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software; D013552:Swine; D013556:Swine, Miniature; D018084:Ultrasonography, Interventional
chemical_list: D008055:Lipids