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Co-analysis of Brain Structure and Function using fMRI and Diffusion-weighted Imaging
Published on: November 8, 2012
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Fiber orientation distribution from diffusion MRI: Effects of inaccurate response function calibration
Fenghua Guo1, Chantal M W Tax1,2, Alberto De Luca1
1Image Sciences Institute, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands.
Summary
Accurate response function shape is crucial for diffusion MRI analysis. Inaccurate shapes in spherical deconvolution can distort fiber orientation distributions (FODs) and lead to spurious peaks, impacting white matter tractography.
Area of Science:
- Neuroimaging
- Biomedical Engineering
- Computational Neuroscience
Background:
- Diffusion MRI noninvasively quantifies white matter fiber orientations.
- Spherical deconvolution is a key method for estimating fiber orientation distribution (FOD).
- Accurate response function definition is critical for FOD computation.
Purpose of the Study:
- To investigate the impact of response function shape inaccuracies on FOD characteristics.
- To understand how response function errors affect white matter tractography.
Main Methods:
- Simulations were used to model the effects of response function shape factor errors.
- In vivo diffusion MRI data were analyzed with modified response functions.
Main Results:
- Underestimated shape factors doubled apparent fiber density; overestimated factors caused spurious FOD peaks (SNR < 15).
- Fiber populations with <60° separation were more sensitive to response function inaccuracies.
- In vivo data showed FOD angular deviations and spurious peaks, but main fiber bundles were preserved.
Conclusions:
- Response function shape significantly influences FOD estimation in diffusion MRI.
- Proper calibration and definition of the response function are essential for reliable white matter analysis.
