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An exploration of diffusion tensor eigenvector variability within human calf muscles.
- Source :
- Journal of Magnetic Resonance Imaging; Jan2016, Vol. 43 Issue 1, p190-202, 13p, 3 Color Photographs, 1 Diagram, 2 Charts, 4 Graphs
- Publication Year :
- 2016
-
Abstract
- <bold>Purpose: </bold>To explore the effect of diffusion tensor imaging (DTI) acquisition parameters on principal and minor eigenvector stability within human lower leg skeletal muscles.<bold>Materials and Methods: </bold>Lower leg muscles were evaluated in seven healthy subjects at 3T using an 8-channel transmit/receive coil. Diffusion-encoding was performed with nine signal averages (NSA) using 6, 15, and 25 directions (NDD). Individual DTI volumes were combined into aggregate volumes of 3, 2, and 1 NSA according to number of directions. Tensor eigenvalues (λ1 , λ2 , λ3 ), eigenvectors (ε1 , ε2 , ε3 ), and DTI metrics (fractional anisotropy [FA] and mean diffusivity [MD]) were calculated for each combination of NSA and NDD. Spatial maps of signal-to-noise ratio (SNR), λ3 :λ2 ratio, and zenith angle were also calculated for region of interest (ROI) analysis of vector orientation consistency.<bold>Results: </bold>ε1 variability was only moderately related to ε2 variability (r = 0.4045). Variation of ε1 was affected by NDD, not NSA (P < 0.0002), while variation of ε2 was affected by NSA, not NDD (P < 0.0003). In terms of tensor shape, vector variability was weakly related to FA (ε1 :r = -0.1854, ε2 : ns), but had a stronger relation to the λ3 :λ2 ratio (ε1 :r = -0.5221, ε2 :r = -0.1771). Vector variability was also weakly related to SNR (ε1 :r = -0.2873, ε2 :r = -0.3483). Zenith angle was found to be strongly associated with variability of ε1 (r = 0.8048) but only weakly with that of ε2 (r = 0.2135).<bold>Conclusion: </bold>The second eigenvector (ε2 ) displayed higher directional variability relative to ε1 , and was only marginally affected by experimental conditions that impacted ε1 variability. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 10531807
- Volume :
- 43
- Issue :
- 1
- Database :
- Complementary Index
- Journal :
- Journal of Magnetic Resonance Imaging
- Publication Type :
- Academic Journal
- Accession number :
- 112015244
- Full Text :
- https://doi.org/10.1002/jmri.24957