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Model-based analysis of multishell diffusion MR data for tractography: how to get over fitting problems

Jbabdi, Saad; Sotiropoulos, Stamatios N.; Savio, Alexander M.; Graña, Manuel; Behrens, Timothy E.J.

Authors

Saad Jbabdi

Stamatios N. Sotiropoulos

Alexander M. Savio

Manuel Graña

Timothy E.J. Behrens



Abstract

In this article, we highlight an issue that arises when using multiple b‐values in a model‐based analysis of diffusion MR data for tractography. The non‐monoexponential decay, commonly observed in experimental data, is shown to induce overfitting in the distribution of fiber orientations when not considered in the model. Extra fiber orientations perpendicular to the main orientation arise to compensate for the slower apparent signal decay at higher b‐values. We propose a simple extension to the ball and stick model based on a continuous gamma distribution of diffusivities, which significantly improves the fitting and reduces the overfitting. Using in vivo experimental data, we show that this model outperforms a simpler, noise floor model, especially at the interfaces between brain tissues, suggesting that partial volume effects are a major cause of the observed non‐monoexponential decay. This model may be helpful for future data acquisition strategies that may attempt to combine multiple shells to improve estimates of fiber orientations in white matter and near the cortex.

Citation

Jbabdi, S., Sotiropoulos, S. N., Savio, A. M., Graña, M., & Behrens, T. E. (2012). Model-based analysis of multishell diffusion MR data for tractography: how to get over fitting problems. Magnetic Resonance in Medicine, 68(6), https://doi.org/10.1002/mrm.24204

Journal Article Type Article
Acceptance Date Jan 17, 2012
Online Publication Date Feb 14, 2012
Publication Date Nov 21, 2012
Deposit Date Jul 12, 2018
Publicly Available Date Jul 12, 2018
Journal Magnetic Resonance in Medicine
Print ISSN 0740-3194
Electronic ISSN 1522-2594
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 68
Issue 6
DOI https://doi.org/10.1002/mrm.24204
Public URL http://eprints.nottingham.ac.uk/id/eprint/52902
Publisher URL https://onlinelibrary.wiley.com/doi/abs/10.1002/mrm.24204
Copyright Statement Copyright information regarding this work can be found at the following address: http://eprints.nottingham.ac.uk/end_user_agreement.pdf

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://eprints.nottingham.ac.uk/end_user_agreement.pdf





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