5 results for Axel, L

  • Deformable models with parameter functions for cardiac motion analysis from tagged MRI data

    Park, J; Metaxas, D; Young, Alistair; Axel, L (1996)

    Journal article
    The University of Auckland Library

    We present a new method for analyzing the motion of the heart's left ventricle (LV) from tagged magnetic resonance imaging (MRI) data, Our technique is based on the development of a new class of physics-based deformable models whose parameters are fu

    View record details
  • Tracking and finite element analysis of stripe deformation in magnetic resonance tagging.

    Young, Alistair; Kraitchman, DL; Dougherty, L; Axel, L (1995)

    Journal article
    The University of Auckland Library

    Magnetic resonance tissue tagging allows noninvasive in vivo measurement of soft tissue deformation. Planes of magnetic saturation are created, orthogonal to the imaging plane, which form dark lines (stripes) in the image. The authors describe a method for tracking stripe motion in the image plane, and show how this information can be incorporated into a finite element model of the underlying deformation. Human heart data were acquired from several imaging planes in different orientations and were combined using a deformable model of the left ventricle wall. Each tracked stripe point provided information on displacement orthogonal to the original tagging plane, i.e., a one-dimensional (1-D) constraint on the motion. Three-dimensional (3-D) motion and deformation was then reconstructed by fitting the model to the data constraints by linear least squares. The average root mean squared (rms) error between tracked stripe points and predicted model locations was 0.47 mm (n=3,100 points). In order to validate this method and quantify the errors involved, the authors applied it to images of a silicone gel phantom subjected to a known, well-controlled, 3-D deformation. The finite element strains obtained were compared to an analytic model of the deformation known to be accurate in the central axial plane of the phantom. The average rms errors were 6% in both the reconstructed shear strains and 16% in the reconstructed radial normal strain.

    View record details
  • Right ventricular midwall surface motion and deformation using magnetic resonance tagging

    Young, Alistair; Fayad, ZA; Axel, L (1996)

    Journal article
    The University of Auckland Library

    We describe a method for reconstructing the three-dimensional motion and deformation of the midwall surface of the right ventricular free wall (RVFW) using magnetic resonance tissue tagging. Tag points were defined where the tag stripes intersected t

    View record details
  • Right ventricular regional function using MR tagging: Normals versus chronic pulmonary hypertension

    Fayad, ZA; Ferrari, VA; Kraitchman, DL; Young, Alistair; Palevsky, HI; Bloomgarden, DC; Axel, L (1998)

    Journal article
    The University of Auckland Library

    Right ventricular (RV) regional function, in both normal and diseased states, is not well characterized. Using 1D MR myocardial tagging, RV and septal intramyocardial segmental shortening was noninvasively measured in ten healthy subjects and in seve

    View record details
  • Integrated MRI assessment of regional function and perfusion in canine myocardial infarction

    Kraitchman, DL; Young, Alistair; Bloomgarden, DC; Fayad, ZA; Dougherty, L; Ferrari, VA; Boston, RC; Axel, L (1998)

    Journal article
    The University of Auckland Library

    A single integrated examination using regional measurements of perfusion from contrast-enhanced MRI and three-dimensional (3D) strain from tissue-tagged MRI was developed to differentiate infarcted myocardium from adjacent tissue with functional abno

    View record details