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Updated: May 5, 2026
Co-analysis of Brain Structure and Function using fMRI and Diffusion-weighted Imaging
Published on: November 8, 2012
Spurious group differences due to head motion in a diffusion MRI study
Anastasia Yendiki1, Kami Koldewyn2, Sita Kakunoori1
1Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
Abstract:
Diffusion-weighted MRI (DW-MRI) has become a popular imaging modality for probing the microstructural properties of white matter and comparing them between populations in vivo. However, the contrast in DW-MRI arises from the microscopic random motion of water molecules in brain tissues, which makes it particularly sensitive to macroscopic head motion. Although this has been known since the introduction of DW-MRI, most studies that use this modality for group comparisons do not report measures of head motion for each group and rely on registration-based correction methods that cannot eliminate the full effects of head motion on the DW-MRI contrast. In this work we use data from children with autism and typically developing children to investigate the effects of head motion on differences in anisotropy and diffusivity measures between groups. We show that group differences in head motion can induce group differences in DW-MRI measures, and that this is the case even when comparing groups that include control subjects only, where no anisotropy or diffusivity differences are expected. We also show that such effects can be more prominent in some white-matter pathways than others, and that they can be ameliorated by including motion as a nuisance regressor in the analyses. Our results demonstrate the importance of taking head motion into account in any population study where one group might exhibit more head motion than the other.
Insights
Head motion significantly impacts diffusion-weighted MRI (DW-MRI) findings in group studies. Accounting for head motion is crucial for accurate comparisons of white matter microstructure, especially in pediatric populations.
Area of Science:
- Neuroimaging
- Biomedical Engineering
- Developmental Neuroscience
Background:
- Diffusion-weighted MRI (DW-MRI) is vital for assessing white matter microstructure in vivo.
- DW-MRI's sensitivity to water molecule motion makes it vulnerable to head motion artifacts.
- Existing correction methods often fail to fully address head motion's impact on DW-MRI contrast.
Purpose of the Study:
- To investigate the influence of head motion on diffusion MRI measures in children with autism versus typically developing children.
- To determine if group differences in head motion can create spurious group differences in diffusion MRI metrics.
- To evaluate strategies for mitigating head motion effects in population-based DW-MRI studies.
Main Methods:
- Utilized DW-MRI data from pediatric cohorts (autism and typically developing).
- Analyzed anisotropy and diffusivity measures, correlating them with head motion.
- Employed statistical models including motion as a nuisance regressor.
Main Results:
- Group differences in head motion were shown to induce artificial group differences in DW-MRI measures.
- These motion-induced effects were observed even in control-only comparisons.
- Motion effects varied across white matter pathways and could be reduced by including motion as a covariate.
Conclusions:
- Head motion is a critical confounder in population-based DW-MRI studies.
- Failure to account for differential head motion can lead to erroneous conclusions about white matter differences.
- Future DW-MRI research must incorporate robust motion assessment and correction strategies.
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