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Understanding intensity non-uniformity in MRI

  • John G. Sled
  • G. Bruce Pike
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 1496)

Abstract

Motivated by the observation that the diagonal pattern of intensity non-uniformity usually associated with linearly polarized radio-frequency (RF) coils is often present in neurological scans using circularly polarized coils, a theoretical analysis has been conducted of the intensity non-uniformity inherent in imaging an elliptically shaped object using 1.5 T magnets and circularly polarized RF coils. While an elliptic geometry is too simple to accurately predict the variations in individual anatomical scans, we use it to investigate a number of observations and hypotheses. (i) The widely made assumption that the data is corrupted by a smooth multiplicative field is accurate for proton density images. (ii) The pattern of intensity variation is highly dependent on the shape of the object being scanned. (iii) Elliptically shaped objects produce a diagonal pattern of variation when scanned using circularly polarized coils.

Keywords

Shaped Object Reception Sensitivity Elliptic Cylinder Excitation Field Birdcage Coil 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

References

  1. 1.
    E. R. McVeigh, M. J. Bronskill, and R. M. Henkelman, “Phase and sensitivity of receiver coils in magnetic resonance imaging,” Med. Phys., vol. 13, pp. 806–814, Nov./Dec. 1986.CrossRefPubMedPubMedCentralGoogle Scholar
  2. 2.
    A. Simmons, P. S. Tofts, G. J. Barker, and S. R. Arridge, “Sources of intensity nonuniformity in spin echo images,” Magn. Reson. Med., vol. 32, pp. 121–128, 1994.CrossRefPubMedGoogle Scholar
  3. 3.
    P. A. Bottomley and E. R. Andrew, “RF magnetic field penetration, phase shift and power dissipation in biological tissue: implications for NMR imaging,” Physics in Medicine and Biology, vol. 23, pp. 630–43, Jul 1978.CrossRefPubMedGoogle Scholar
  4. 4.
    J. G. Sled and A. C. E. Alex P. Zijdenbos, D. Louis Collins, “The impact of intensity non-uniformity on automated anatomical analysis of 3d mri images,” in Third International Conference on Functional Mapping of the Human Brain, p. S399, 1997.Google Scholar
  5. 5.
    B. R. Condon, J. Patterson, D. Wyper, et al., “Image non-uniformity in magnetic resonance imaging: its magnitude and methods for its correction,” Br. J. Radiology, vol. 60, pp. 83–87, 1987.CrossRefGoogle Scholar
  6. 6.
    B. M. Dawant, A. P. Zijdenbos, and R. A. Margolin, “Correction of intensity variations in MR images for computer-aided tissue classification,” IEEE Trans. Med. Imag., vol. 12, pp. 770–781, Dec. 1993.CrossRefGoogle Scholar
  7. 7.
    C. R. Meyer, P. H. Bland, and J. Pipe, “Retrospective correction of intensity inhomogeneities in MRI,” IEEE Transactions on Medical Imaging, vol. 14, pp. 36–41, Mar. 1995.CrossRefPubMedGoogle Scholar
  8. 8.
    W. M. Wells III, W. E. L. Grimson, R. Kikinis, and F. A. Jolesz, “Actaptive segmentation of MRI data,” IEEE Trans. Med. Imag., vol. 15, no. 4, pp. 429–442, 1996.CrossRefGoogle Scholar
  9. 9.
    J. G. Sled, A. P. Zijdenbos, and A. C. Evans, “A non-parametric method for automatic correction of intensity non-uniformity in MRI data,” IEEE Trans. Med. Imag., vol. 17, pp. 87–97, February 1998.CrossRefGoogle Scholar
  10. 10.
    G. O. Glover, C. E. Hayes, N. J. Pelc, W. A. Edelstein, O.M. Mueller, H. R. Hart, C. J. Hardy, M. O’Donnel, and W. D. Barber, “Comparison of linear and circular polarization for magnetic resonance imaging,” J. Magn. Reson., vol. 64, pp. 255–270, 1985.Google Scholar
  11. 11.
    J. G. Sled and G. B. Pike, “Standing-wave and RF penetration artifacts caused by elliptic geometry: an electrodynamic analysis of MRI,” IEEE Trans. Med. Imag., 1997. (submitted).Google Scholar
  12. 12.
    P. S. Tofts, “Standing waves in uniform water phantoms,” J. Magn. Reson. B, vol. 104, pp. 143–147, 1994.CrossRefGoogle Scholar
  13. 13.
    P. S. Neelakanta, Handbook of electromagnetic materials: monolithic and composite versions and their applications, pp. 577–584. CRC Press, 1995.Google Scholar
  14. 14.
    D. Simunic, P. Wach, W. Renhart, and R. Stollberger, “Spatial distribution of high-frequency electromagnetic energy in human head during MRI: numerical results and measurements,” IEEE Transactions on Biomedical Engineering, vol. 43, pp. 88–94, Jan 1996.CrossRefPubMedGoogle Scholar
  15. 15.
    S. Topp, E. Actalsteinsson, and D. M. Spielman, “Fast multislice B 1-mapping,” in International Society for Magnetic Resonance in Medicine, vol. 1, p. 281, 1997.Google Scholar
  16. 16.
    D. L. Collins, P. Neelin, T. M. Peters, and A. C. Evans, “Automatic 3D intersubject registration of MR volumetric data in standardized Talairach space,” J. Comput. Assist. Tomogr., vol. 18, no. 2, pp. 192–205, 1994.CrossRefPubMedGoogle Scholar
  17. 17.
    MNI Automated Linear Registration Package, Version 0.98, 1997. Available by anonymous ftp at ftp://ftp.bic.mni.mcgill.ca/pub/mni_autoreg/Google Scholar
  18. 18.
    N. Otsu, “A threshold selection method from gray-level histograms,” IEEE Transactions on Biomedical Engineering, vol. 9, pp. 63–66, 1979.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • John G. Sled
    • 1
  • G. Bruce Pike
    • 1
  1. 1.McConnell Brain Imaging Centre, Montréal Neurological InstituteMcGill UniversityMontréalCanada

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