Chinese Journal of Magnetic Resonance ›› 2016, Vol. 33 ›› Issue (4): 609-617.doi: 10.11938/cjmr20160410

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A Phase Fitting Algorithm for Multi-Echo Quantitative Susceptibility Mapping

ZHAO Xin-xin1, BO Bin-shi1, LIU Tian2, WANG Yi1,2,3, LI Jian-qi1   

  1. 1. Shanghai Key Laboratory of Magnetic Resonance, Department of Physics, East China Normal University, Shanghai 200062, China;
    2. Department of Radiology, Weill Medical College, Cornell University, Ithaca, New York 10021, USA;
    3. Department of Biomedical Engineering, Cornell University, Ithaca, New York 14853, USA
  • Received:2016-04-04 Revised:2016-10-24 Online:2016-12-05 Published:2016-12-05

Abstract: A weighted linear least-square (WLS) algorithm is generally applied for multi-echo phase data to estimate the voxel-by-voxel field shift, which is further used for inversion of susceptibility map. The fitting error on the estimated field map, induced from conventional WLS method, may lead to artifacts and low signal-to-noise ratio on the susceptibility map, especially in the regions with inhomogeneous distribution of magnetic susceptibility. To improve the accuracy of the estimated field map, a truncated WLS approach was used to truncate the signal of low signal-to-noise ratio and capture the field information before the signal in a voxel decays to the noise level, which can enhance the contrast of structures in the bottom of the brain on the susceptibility map. Experimental studies demonstrated that susceptibility noise was dramatically reduced by method of truncated WLS.

Key words: quantitative susceptibility mapping(QSM), multi-echo phases fitting, threshold truncation, weighted linear least-square(WLS)

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