Tensor-valued diffusion MRI differentiates cortex and white matter in malformations of cortical development...

Area of Science:

• Neuroimaging
• Medical Physics
• Neurology

Background:

• Accurate delineation of malformations of cortical development (MCD) is crucial for epilepsy presurgical evaluation.
• Conventional MRI contrasts (T1/T2-weighted) rely on myelin, leading to ambiguity in differentiating cortical and white matter in MCD.
• Myelin variations can alter MCD appearance on MRI, potentially causing discrepancies with histopathology.

Purpose of the Study:

• To investigate the utility of novel tensor-valued diffusion MRI (dMRI) for improved differentiation of cortex and white matter in MCD.
• To assess if tensor-valued dMRI can enhance the delineation of MCD in the context of epilepsy.

Main Methods:

• Tensor-valued dMRI was acquired using a 7 Tesla MRI scanner in 13 MCD patients.
• Patients presented with various MCD types including heterotopias, focal cortical dysplasia, and polymicrogyria.
• Microscopic anisotropy maps were generated and compared with conventional MRI (T1/T2) and diffusion tensor imaging (DTI).

Main Results:

• Microscopic anisotropy maps identified extensive white matter-like regions within MCD that appeared cortex-like on conventional MRI.
• These discrepancies were particularly noted in deep white matter of subcortical heterotopias and near gray-white matter boundaries in other MCD types.
• Tensor-valued dMRI revealed distinct patterns not apparent with standard MRI contrasts.

Conclusions:

• Tensor-valued dMRI, by mapping microscopic anisotropy sensitive to axons, provides more robust differentiation of cortex and white matter in MCD.
• This improved differentiation holds promise for enhancing MCD delineation in presurgical evaluations for drug-resistant epilepsy.
• The findings suggest tensor-valued dMRI as a valuable tool for complex neurodevelopmental disorder imaging.