title: Intravascular two-dimensional tissue strain imaging.
abstract: Our goal is to achieve the precise quantitative imaging of tissue elasticity in clinical settings. In the present study, we measured basic ultrasonic characteristics of atherosclerosis by two-dimensional (2D) intravascular tissue velocity imaging. Radio-frequency (RF) signal from a clinically used IVUS apparatus was digitized at 500 MSa/s and stored in a workstation. First, the correlation coefficient between two consecutive frames was calculated in the rotational direction and the rotational disuniformity was corrected to obtain the maximum correlation coefficient. Then, the polar coordinate images were converted into rectangular coordinate images and the images were divided into 64 by 64 square shaped regions of interest (ROIs). The correlation and displacement of the ROIs between the consecutive two frames were calculated by template matching method. Two-dimensional tissue velocity was defined as the vectors of displacement of ROI with 0.7 and more correlation. IVUS studies were performed in directional coronary atherectomy (DCA) procedures. The specimens excised by DCA were stained with Elastica-Masson's trichrome staining and CD68 immunochemical staining. Eleven cases (including two no re-flow cases and one perforation case) were intraoperatively observed by IVUS and the specimens obtained by DCA were observed by optical microscopy. The specimen from homogeneous 2D strain was collagen dominant fibrosis and the specimen from a lesion with complex vectors contained CD68 positive cells and degenerated collagen fibers, which indicated the plaque was vulnerable.
authors.affiliation: Department of Medical Engineering and Cardiology, Institute of Development, Aging and Cancer, Tohoku University, Seiryomachi, Aoba-ku, Sendai, Japan. saijo@idac.tohoku.ac.jp <saijo@idac.tohoku.ac.jp>
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Saijo
authors.forename: Akira
authors.initials: A
authors.lastname: Tanaka
authors.forename: Takahiro
authors.initials: T
authors.lastname: Iwamoto
authors.forename: Esmeraldo
authors.initials: E
authors.lastname: dos Santos Filho
authors.forename: Makoto
authors.initials: M
authors.lastname: Yoshizawa
authors.forename: Akira
authors.initials: A
authors.lastname: Hirosaka
authors.forename: Mikihiro
authors.initials: M
authors.lastname: Kijima
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Akino
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Hanadate
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Yambe
mesh_terms: D000465:Algorithms; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D004452:Echocardiography / Q000379:methods*; D004548:Elasticity; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D018084:Ultrasonography, Interventional / Q000379:methods*