title: Kinematic analysis of left ventricular deformation in myocardial infarction using magnetic resonance cardiac tagging.
abstract: The Magnetic Resonance (MR) tagging technique provides detailed information about 2D motion in the plane of observation. Interpretation of this information as a reflection of the 3D motion of the entire cardiac wall is a major problem. In finite element models of the mechanics of the infarcted heart, an infarcted region causes motional asymmetry, extending far beyond the infarct boundary. Here we present a method to quantify such asymmetry in amplitude and orientation. For this purpose images of a short-axis cross-section of the ejecting left ventricle were acquired from 9 healthy volunteers and 5 patients with myocardial infarction. MR-tags were applied in a 5 mm grid at end-diastole. The tags were tracked by video-image analysis. Tag motion was fitted to a kinematic model of cardiac motion. For the volunteers and the patients the center of the cavity displaced by about the same amount (p = 0.11) during the ejection phase: 3.8 +/- 1.4 and 3.0 +/- 0.9 mm (mean +/- sd), respectively. Cross-sectional rotation and the decrease in cross-sectional area of the cavity were both greater in the volunteers than in the patients: 6.4 +/- 1.5 vs. 3.0 +/- 0.8 degrees (p < 0.001), and 945 +/- 71 vs. 700 +/- 176 mm2 (p = 0.02), respectively. In the patients, asymmetry of wall motion, as expressed by a sine wave dependency of contraction around the circumference, was significantly enlarged (p = 0.02). The proposed method of kinematic analysis can be used to assess cardiac deformation in humans. We expect that by analyzing images of more cross-sections simultaneously, the 3D location and the degree of infarction can be assessed efficiently.
authors.affiliation: Department of Biophysics, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands.
authors.forename: F W
authors.initials: FW
authors.lastname: Aelen
authors.forename: T
authors.initials: T
authors.lastname: Arts
authors.forename: D G
authors.initials: DG
authors.lastname: Sanders
authors.forename: G R
authors.initials: GR
authors.lastname: Thelissen
authors.forename: F W
authors.initials: FW
authors.lastname: Prinzen
authors.forename: R S
authors.initials: RS
authors.lastname: Reneman
mesh_terms: D001696:Biomechanical Phenomena; D006352:Heart Ventricles / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008433:Mathematics; D008875:Middle Aged; D009200:Myocardial Contraction; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000503:physiopathology; D012372:ROC Curve; D014741:Video Recording