Analysis of cortical dysplasias using b-tensor encoding diffusion MRI in an animal model

Area of Science:

• Neuroimaging
• Neuroscience
• Biomedical Engineering

Background:

• Cortical dysplasias are developmental brain malformations causing epilepsy.
• Conventional imaging struggles to diagnose these conditions, limiting surgical options.
• Diffusion-weighted magnetic resonance imaging (dMRI) offers microscopic tissue insights.

Purpose of the Study:

• To evaluate b-tensor encoded dMRI for assessing neocortical microarchitecture in a murine model of cortical dysplasia.
• To correlate dMRI findings with histological and immunofluorescence data.

Main Methods:

• A rat model of cortical dysplasia was induced using carmustine (BCNU).
• Offspring underwent 7-tesla dMRI with b-tensor encoding and Q-space trajectory imaging (QTI+).
• Brain tissue was analyzed via immunofluorescence and histology.

Main Results:

• BCNU-treated rats showed reduced microscopic fractional anisotropy (µFA) and anisotropic kurtosis (Kshear) in cortical layers.
• Histology revealed disorganized myelinated fibers and increased glial processes in treated animals.
• dMRI metrics correlated with observed microstructural changes.

Conclusions:

• B-tensor encoded dMRI can detect microarchitectural alterations in cortical dysplasia.
• This technique shows potential for improved clinical diagnosis of focal cortical dysplasias in epilepsy patients.
• The approach is compatible with clinical MRI scanners.