Magnetic Resonance Imaging
Volume 28, Issue 2 , Pages 185-194, February 2010

Registering spherical navigators with spherical harmonic expansions to measure three-dimensional rotations in magnetic resonance imaging☆

  • Andreu F. Costa

      Affiliations

    • Imaging Research Laboratories, Robarts Research Institute, University of Western Ontario, London, Ontario, Canada N6A 5K8
    • ,
  • Yi-Fen Yen

      Affiliations

    • Global Applied Science Laboratory, GE Healthcare, Menlo Park, CA 94025, USA
    • ,
  • Maria Drangova

      Affiliations

    • Imaging Research Laboratories, Robarts Research Institute, University of Western Ontario, London, Ontario, Canada N6A 5K8
    • Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada N6A 3K7
    • Department of Medical Imaging, University of Western Ontario, London, Ontario, Canada N6A 3K7
    • Corresponding Author InformationCorresponding author. Imaging Research Laboratories, Robarts Research Institute, P.O. Box 5015, London, Ontario, Canada N6A 5K8. Tel.: +1 519 663 5777x24064; fax: +1 519 931 5260.

Received 21 August 2008; received in revised form 20 January 2009; accepted 18 July 2009. published online 16 September 2009.

Abstract 

Subject motion remains a challenging problem to overcome in clinical and research applications of magnetic resonance imaging (MRI). Subject motion degrades the quality of MR images and the integrity of experimental data. A promising method to correct for subject motion in MRI is the spherical navigator (SNAV) echo. Spherical navigators acquire k-space data on the surface of a sphere in order to measure three-dimensional (3D) rigid-body motion. Analysis begins by registering the magnitude of two SNAVs to determine the 3D rotation between them. Several different methods to register SNAV data exist, each with specific capabilities and limitations. In this study, we assessed the accuracy, precision and computational requirements of measuring rotations about all three coordinate axes by correlating the spherical harmonic expansions of SNAV data. We compare the results of this technique to previous SNAV studies and show that, although computationally expensive, the spherical harmonic technique is a highly accurate, precise and robust method to register SNAVs and detect 3D rotations in MRI. A key advantage to the spherical harmonic technique is the ability to optimize the accuracy, precision, processing time and memory requirements by adjusting parameters used in the registration. While present developments are aimed at improving the programming efficiency and memory handling of the algorithm, this registration technique is currently well suited for retrospective motion correction applications, such as removing motion-related image artifacts and aligning slices within a high-resolution 3D volume.

Keywords: Motion correction, Spherical navigator echo, Rotation group, Spherical harmonics

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☆ Grant sponsors: The Canadian Institutes of Health Research (MGP-49536), The Ontario Research and Development Challenge Fund, The Whitaker Foundation (RG-00-0409). MD is a Career Investigator with the Heart and Stroke Foundation of Ontario.

PII: S0730-725X(09)00183-0

doi:10.1016/j.mri.2009.07.010

Magnetic Resonance Imaging
Volume 28, Issue 2 , Pages 185-194, February 2010

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