Characteristics of abnormal diffusivity in normal-appearing white matter investigated with diffusion tensor MR...

Area of Science:

• Neuroimaging
• White Matter Microstructure
• Diffusion Tensor Imaging

Background:

• Tuberous sclerosis complex (TSC) is associated with various structural abnormalities.
• White matter (WM) changes may exist in TSC even when appearing normal on conventional MRI.

Purpose of the Study:

• To investigate in vivo microstructural changes in normal-appearing white matter (NAWM) in children with TSC using diffusion tensor imaging (DTI).
• To determine if DTI abnormalities in NAWM of TSC patients differ across diffusion directions.

Main Methods:

• DTI was used to assess diffusivity and anisotropy in NAWM of 6 children with TSC and 12 controls.
• Specific WM regions analyzed included the internal capsule, external capsule, and corpus callosum.
• Analysis focused on major, middle, and minor eigenvalues to evaluate directional diffusion differences.

Main Results:

• NAWM in TSC patients showed significantly increased mean diffusivity and decreased anisotropy compared to controls.
• The increase in diffusivity was more pronounced in directions perpendicular to axons (minor and middle eigenvalues).

Conclusions:

• Microstructural changes, including decreased anisotropy and increased radial/longitudinal diffusivities, were found in NAWM of TSC patients.
• These axonal changes likely relate to myelin packing alterations, gliosis, and myelination defects characteristic of TSC.