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Updated: Aug 9, 2026
Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
Published on: July 28, 2013
Diffusion tensor imaging in polymicrogyria: a report of three cases
R Trivedi1, R K Gupta, K M Hasan
1MR Section, Department of Radiodiagnosis, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, UP 226014, India.
Introduction:
Polymicrogyria (PMG), a neuronal migration disorder, commonly manifests as a seizure disorder. The aim of this study was to look for the abnormalities in the underlying white matter using diffusion tensor imaging (DTI) that appeared normal on conventional magnetic resonance imaging (MRI) in patients with PMG.
Methods:
DTI was performed in three patients with PMG and eight age- and sex-matched healthy controls. Fractional anisotropy (FA) and mean diffusivity (MD) values were calculated for the cortex and adjoining subcortical white matter in both controls and patients.
Results:
We observed a significantly decreased mean FA value with no significant change in the MD value in subcortical white matter underlying polymicrogyric cortex (FA = 0.23+/-0.04, MD = 1.0+/-0.05 x 10(-3) mm(2)/s) as compared to both contralateral (FA = 0.32+/-0.04, MD = 1.0+/-0.05 x 10(-3) mm(2)/s) and normal control (FA = 0.32+/-0.04, MD = 1.0+/-0.06 x 10(-3) mm(2)/s) white matter. Significantly increased MD and decreased FA values were also observed in the polymicrogyric cortex (FA = 0.08+/-0.01, MD = 1.2+/-0.10 x 10(-3) mm(2)/s) as compared to normal contralateral (FA = 0.12+/-0.04, MD = 1.1+/-0.09 x 10(-3) mm(2)/s) and normal control (FA = 0.12+/-0.01, MD = 1.1+/-0.09 x 10(-3) mm(2)/s) cortex.
Conclusion:
Significantly decreased FA values with no change in MD values in the subcortical white matter subjacent to polymicrogyric cortex reflect microstructural changes in the white matter probably due to the presence of ectopic neurons.
Insights
Diffusion tensor imaging (DTI) revealed microstructural white matter abnormalities in polymicrogyria (PMG) patients. These subtle changes, not visible on MRI, indicate underlying neuronal migration disorder issues.
Area of Science:
- Neuroimaging
- Neurology
- White Matter Disorders
Background:
- Polymicrogyria (PMG) is a neuronal migration disorder often presenting with seizures.
- Conventional MRI may not detect subtle white matter abnormalities in PMG.
- Diffusion Tensor Imaging (DTI) can reveal microstructural white matter changes.
Observation:
- DTI was performed on three PMG patients and eight healthy controls.
- Fractional Anisotropy (FA) and Mean Diffusivity (MD) values were analyzed in cortical and subcortical white matter.
- Analysis focused on white matter adjacent to polymicrogyric cortex.
Findings:
- Significantly reduced FA in subcortical white matter beneath PMG cortex compared to controls.
- No significant change in Mean Diffusivity (MD) in the subcortical white matter.
- Increased MD and decreased FA observed within the polymicrogyric cortex itself.
Implications:
- Decreased FA in subjacent white matter suggests microstructural alterations in PMG.
- These changes may be attributed to ectopic neurons within the white matter.
- DTI offers a sensitive method for detecting PMG-related white matter pathology.
