101. Optimizing the intrinsic parallel diffusivity in NODDI: An extensive empirical evaluation.
- Author
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Guerrero, Jose M., Adluru, Nagesh, Bendlin, Barbara B., Goldsmith, H. Hill, Schaefer, Stacey M., Davidson, Richard J., Kecskemeti, Steven R., Zhang, Hui, and Alexander, Andrew L.
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OLDER people , *AGE groups , *DIFFUSION magnetic resonance imaging , *DEVELOPMENTAL biology , *CYTOLOGY - Abstract
Purpose: NODDI is widely used in parameterizing microstructural brain properties. The model includes three signal compartments: intracellular, extracellular, and free water. The neurite compartment intrinsic parallel diffusivity (d∥) is set to 1.7 μm2⋅ms−1, though the effects of this assumption have not been extensively explored. This work investigates the optimality of d∥ = 1.7 μm2⋅ms−1 under varying imaging protocol, age groups, sex, and tissue type in comparison to other biologically plausible values of d∥. Methods: Model residuals were used as the optimality criterion. The model residuals were evaluated in function of d∥ over the range from 0.5 to 3.0 μm2⋅ms−1. This was done with respect to tissue type (i.e., white matter versus gray matter), sex, age (infancy to late adulthood), and diffusion-weighting protocol (maximum b-value). Variation in the estimated parameters with respect to d∥ was also explored. Results: Results show d∥ = 1.7 μm2⋅ms−1 is appropriate for adult brain white matter but it is suboptimal for gray matter with optimal values being significantly lower. d∥ = 1.7 μm2⋅ms−1 was also suboptimal in the infant brain for both white and gray matter with optimal values being significantly lower. Minor optimum d∥ differences were observed versus diffusion protocol. No significant sex effects were observed. Additionally, changes in d∥ resulted in significant changes to the estimated NODDI parameters. Conclusion: The default (d∥) of 1.7 μm2⋅ms−1 is suboptimal in gray matter and infant brains. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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