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Intra-voxel and inter-voxel coherence in patients with multiple sclerosis assessed using diffusion tensor MRI
M Cercignani1, M Bozzali, G Iannucci
1Neuroimaging Research Unit, Dept. of Neuroscience, Scientific Institute and University, Ospedale San Raffaele, via Olgettina 60, 20132 Milan, Italy.
Journal of Neurology
|July 26, 2002
Summary
Inter-voxel coherence (C) analysis in diffusion tensor imaging (DT-MRI) reveals additional information on multiple sclerosis (MS) tissue damage. This DT-MRI metric complements mean diffusivity and fractional anisotropy in quantifying MS-related changes.
Area of Science:
- Neuroimaging
- Biomedical Engineering
- Radiology
Background:
- Previous diffusion tensor magnetic resonance imaging (DT-MRI) studies in multiple sclerosis (MS) primarily focused on mean diffusivity (MD) and fractional anisotropy (FA).
- These studies often overlooked the potential diagnostic value of inter-voxel coherence (C) in assessing MS-related tissue damage.
- Understanding diffuse changes in normal-appearing white matter (NAWM) and characterizing lesion heterogeneity remain critical challenges in MS research.
Purpose of the Study:
- To evaluate the role of inter-voxel coherence (C) in quantifying tissue damage in T2-visible lesions and normal-appearing white matter (NAWM) in patients with MS.
- To compare DT-MRI metrics (MD, FA, and C) across different MS subtypes (relapsing-remitting, secondary progressive, primary progressive) and healthy controls.
- To investigate the correlation between DT-MRI metrics, particularly C, and clinical disability in MS patients.
Main Methods:
- Acquisition of dual-echo, T1-weighted, and DT-MRI scans from 78 MS patients and 26 healthy volunteers.
- Calculation of mean diffusivity (MD), fractional anisotropy (FA), and inter-voxel coherence (C) for various lesion types (T2-hyperintense, T1-isointense, T1-hypointense) and NAWM regions.
- Statistical comparison of DT-MRI metrics between MS patient groups, lesion types, and controls, and correlation analysis with disability scores.
Main Results:
- Significant differences in MD and FA were observed in most NAWM regions between MS patients and controls.
- Lower NAWM C was found in MS patients compared to controls only in parietal pericallosal areas.
- Secondary progressive MS (SPMS) patients exhibited distinct corpus callosum MD, FA, and C compared to RRMS and PPMS patients; SPMS also showed higher average lesion load.
Conclusions:
- DT-MRI metrics, including MD and FA, effectively identify MS lesions and detect diffuse changes in NAWM.
- Inter-voxel coherence (C) provides complementary information to MD and FA, enhancing the quantification of MS-related tissue damage.
- C analysis holds potential for improved characterization of MS pathology and its correlation with clinical disability.