Improvement of Reliability of Diffusion Tensor Metrics in Thigh Skeletal Muscles

Sarah Keller, Avneesh Chhabra, Shaheen Ahmed, Anne C. Kim, Jonathan M. Chia, Jin Yamamura, Zhiyue J. Wang

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Objective: Quantitative diffusion tensor imaging (DTI) of skeletal muscles is challenging due to the bias in DTI metrics, such as fractional anisotropy (FA) and mean diffusivity (MD), related to insufficient signal-to-noise ratio (SNR). This study compares the bias of DTI metrics in skeletal muscles via pixel-based and region-of-interest (ROI)-based analysis. Methods: DTI of the thigh muscles was conducted on a 3.0-T system in N = 11 volunteers using a fat-suppressed single-shot spin-echo echo planar imaging (SS SE-EPI) sequence with eight repetitions (number of signal averages (NSA) = 4 or 8 for each repeat). The SNR was calculated for different NSAs and estimated for the composite images combining all data (effective NSA = 48) as standard reference. The bias of MD and FA derived by pixel-based and ROI-based quantification were compared at different NSAs. An “intra-ROI diffusion direction dispersion angle (IRDDDA)” was calculated to assess the uniformity of diffusion within the ROI. Results: Using our standard reference image with NSA = 48, the ROI-based and pixel-based measurements agreed for FA and MD. Larger disagreements were observed for the pixel-based quantification at NSA = 4. MD was less sensitive than FA to the noise level. The IRDDDA decreased with higher NSA. At NSA = 4, ROI-based FA showed a lower average bias (0.9% vs. 37.4%) and narrower 95% limits of agreement compared to the pixel-based method. Conclusion: The ROI-based estimation of FA is less prone to bias than the pixel-based estimations when SNR is low. The IRDDDA can be applied as a quantitative quality measure to assess reliability of ROI-based DTI metrics.

Original languageEnglish (US)
Pages (from-to)55-60
Number of pages6
JournalEuropean Journal of Radiology
StatePublished - May 2018


  • Diffusion tensor imaging
  • Fractional anisotropy
  • Magnetic resonance imaging
  • Mean diffusivity
  • Skeletal muscle

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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