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Tract-based morphometry
Lauren J O'Donnell1, Carl-Fredrik Westin, Alexandra J Golby
1Golby Surgical Brain Mapping Laboratory, Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston MA, USA. odonnell@bwh.harvard.edu
Abstract:
Multisubject statistical analyses of diffusion tensor images in regions of specific white matter tracts have commonly measured only the mean value of a scalar invariant such as the fractional anisotropy (FA), ignoring the spatial variation of FA along the length of fiber tracts. We propose to instead perform tract-based morphometry (TBM), or the statistical analysis of diffusion MRI data in an anatomical tract-based coordinate system. We present a method for automatic generation of white matter tract arc length parameterizations, based on learning a fiber bundle model from tractography from multiple subjects. Our tract-based coordinate system enables TBM for the detection of white matter differences in groups of subjects. We present example TBM results from a study of interhemispheric differences in FA.
Insights
This study introduces tract-based morphometry (TBM) for analyzing diffusion MRI data, moving beyond mean fractional anisotropy (FA) values. TBM reveals spatial variations in white matter tracts, enhancing group comparison and detecting subtle differences.
Area of Science:
- Neuroimaging
- Diffusion MRI
- White Matter Analysis
Background:
- Traditional diffusion tensor imaging (DTI) analysis often uses mean fractional anisotropy (FA) values.
- This approach overlooks spatial variations in FA along white matter tracts.
- A more detailed analysis is needed to capture tract-specific morphometric differences.
Purpose of the Study:
- To introduce tract-based morphometry (TBM) for statistical analysis of diffusion MRI data.
- To develop an automated method for generating white matter tract arc length parameterizations.
- To enable the detection of group differences in white matter structure using an anatomical tract-based coordinate system.
Main Methods:
- Developed an automated method for white matter tract arc length parameterization.
- Created an anatomical tract-based coordinate system for statistical analysis.
- Applied TBM to analyze interhemispheric differences in fractional anisotropy (FA).
Main Results:
- Demonstrated the capability of TBM to perform statistical analyses along the entire length of white matter tracts.
- Successfully generated tract-based coordinate systems from multi-subject tractography data.
- Presented example TBM results highlighting interhemispheric differences in FA.
Conclusions:
- Tract-based morphometry (TBM) offers a more comprehensive approach to analyzing white matter structure compared to traditional methods.
- The automated tract parameterization and coordinate system facilitate robust group comparisons.
- TBM is effective in detecting subtle white matter differences, such as interhemispheric FA variations.
