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Updated: Jul 9, 2026
Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
Published on: July 28, 2013
Can we differentiate true white matter fibers from pseudofibers inside a brain abscess cavity using geometrical
Manoj Kumar1, Rakesh K Gupta, Kavindra Nath
1Department of Radiodiagnosis, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, UP, India.
Abstract:
High fractional anisotropy (FA) usually reflects the orientation and integrity of white matter (WM) fibers. Other regions of increased FA have been described, such as brain abscesses, developing cortex, and areas of hemorrhage. It may not be possible to differentiate true fibers from the pseudofibers found inside an abscess cavity on the basis of FA and mean diffusivity (MD). The aim of this study was to differentiate true WM fibers from pseudo WM tracts inside the abscess cavity using geometrical diffusion tensor imaging metrics [linear anisotropy (CL), planar anisotropy (CP), and spherical anisotropy (CS)]. Diffusion tensor imaging was performed in 42 patients with brain abscess and 10 age/sex-matched controls. Automated segmentation using Java-based software divided the abscess cavity into two sub-regions with FA < 0.20 and FA > or = 0.20. Quantitation was carried out on the sub-regions of the abscess cavity with FA > or = 0.20. In healthy controls, regions of interest were placed on the corpus callosum, posterior limb of the internal capsule, and periventricular and subcortical WM. Significantly increased CP values were observed inside the abscess cavity compared with various normal WM regions. Significantly increased FA and CL values were observed in the abscess cavity compared with subcortical WM only. However decreased FA and CL values were observed in the cavity compared with the corpus callosum, posterior limb of the internal capsule, and periventricular WM. The 95% confidence intervals of means for the abscess cavity were well separated from those for WM in the case of CL and CP; however, they overlapped in the case of FA, MD, and CS. High CP with low CL inside the abscess cavity suggests that the shape of the diffusion tensor is predominantly planar, whereas it is linear in WM tracts. These geometrical indices may have advantages over FA for differentiating true from pseudo WM tracts inside the abscess cavity.
Insights
New diffusion tensor imaging metrics can distinguish true white matter (WM) fibers from pseudofibers in brain abscesses. Geometrical indices like planar anisotropy (CP) offer better differentiation than fractional anisotropy (FA).
Area of Science:
- Neuroimaging
- Radiology
- Biomedical Engineering
Background:
- High fractional anisotropy (FA) typically indicates white matter (WM) integrity but can also be elevated in brain abscesses, hindering differentiation from true fibers.
- Distinguishing true WM fibers from pseudofibers within abscess cavities using conventional diffusion tensor imaging (DTI) metrics like FA and mean diffusivity (MD) is challenging.
Purpose of the Study:
- To differentiate true WM fibers from pseudo WM tracts within brain abscess cavities using geometrical DTI metrics.
- To evaluate the utility of linear anisotropy (CL), planar anisotropy (CP), and spherical anisotropy (CS) in distinguishing these structures.
Main Methods:
- Diffusion tensor imaging (DTI) was performed on 42 patients with brain abscesses and 10 age/sex-matched controls.
- Automated segmentation divided abscess cavities into sub-regions based on FA values (<0.20 and >=0.20).
- Geometrical DTI metrics (CL, CP, CS) were quantified in abscess sub-regions and compared to normal WM regions (corpus callosum, internal capsule, periventricular, subcortical WM).
Main Results:
- Significantly increased planar anisotropy (CP) was observed within abscess cavities compared to normal WM.
- Fractional anisotropy (FA) and linear anisotropy (CL) were higher in abscess cavities than subcortical WM but lower than other normal WM regions.
- Confidence intervals for CL and CP were well-separated between abscess cavities and WM, unlike FA, MD, and CS, suggesting better discriminative power.
Conclusions:
- High CP with low CL in abscess cavities indicates a predominantly planar diffusion tensor shape, contrasting with the linear shape in true WM tracts.
- Geometrical DTI indices, particularly CP and CL, show promise for differentiating true WM fibers from pseudofibers within brain abscesses, outperforming FA and MD.
