Stimulated echo induced misestimates on diffusion tensor indices and its remedy

Tzu Chao Chuang*, Ming Ting Wu, Teng Yi Huang, Yi Ru Lin, Shang Yueh Tsai, Hing Chiu Chang, Hsiao Wen Chung

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Purpose: To report possible erroneous estimates of diffusion parameters in the twice-refocused spin-echo (TRSE) technique, proposed to eliminate eddy-current-induced geometric distortions in diffusion-weighted echo-planar imaging, when stimulated echo signals are inappropriately included. Materials and Methods: Eleven subjects were included for imaging experiments on two 1.5 Tesla systems using the TRSE sequence. Three versions, two with unbalanced crusher gradients inserted to dephase the stimulated echo from the b = 0 images and one with balanced crusher gradients, were implemented. The apparent diffusion coefficients (ADC) and fractional anisotropy (FA) were derived and compared. Results: The ADCs obtained with unbalanced crusher gradients were closer to values reported in the literature. Stimulated echo led to ADC over-estimations by 34.2%, 50.4%, 54.0%, 51.5%, 24.0%, and 41.9% in the genu of corpus callosum, splenium of corpus callosum, bilateral corona radiata, internal capsule, mediofrontal gyrus, and the cuneus, respectively (P < 0.01), with concomitant reduction in FA in highly anisotropic regions. Over-estimations of diffusion coefficients were found to be roughly equal along all directions. Conclusion: Formation of stimulated echo in the TRSE technique can lead to erroneous estimations of the diffusion parameters, even if no prominent morphological artifacts are seen.

Original languageEnglish
Pages (from-to)1522-1529
Number of pages8
JournalJournal of Magnetic Resonance Imaging
Volume31
Issue number6
DOIs
StatePublished - Jun 2010

Keywords

  • Apparent diffusion coefficient
  • Diffusion-weighted imaging
  • Eddy current
  • Fractional anisotropy
  • Stimulated echo
  • Twice-refocused spin-echo

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