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)


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.


Shaped Object Reception Sensitivity Elliptic Cylinder Excitation Field Birdcage Coil 
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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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