The topography of brain microstructural damage in amyotrophic lateral sclerosis assessed using diffusion tensor MR...

Area of Science:

• Neuroimaging
• Neurology
• Biomedical Engineering

Background:

• Amyotrophic Lateral Sclerosis (ALS) is characterized by central nervous system abnormalities, including macrostructural changes like cortical atrophy and microstructural damage.
• Assessing microstructural damage independently of macrostructural volume loss is crucial for understanding ALS progression.

Purpose of the Study:

• To investigate microstructural central nervous system changes in ALS patients compared to healthy controls (HCs) using a multimodal voxelwise imaging approach.
• To identify diffusion tensor imaging (DTI) alterations independent of macrostructural volume loss.

Main Methods:

• Studied 23 ALS patients and 14 HCs using conventional imaging and DTI.
• Processed images with SPM5 to assess gray and white matter atrophy and microstructural damage (mean diffusivity [MD] and fractional anisotropy [FA]).
• Investigated DTI alterations independent of volume loss.

Main Results:

• ALS patients showed increased MD in orbitofrontal and frontotemporal regions, corpus callosum, and internal capsule when accounting for gray and white matter atrophy.
• ALS patients exhibited decreased FA along the corticospinal tract and in the inferior frontal lobe when accounting for white matter loss.
• Increased MD in orbitofrontal regions correlated with disease duration.

Conclusions:

• DTI can detect microstructural changes in ALS independent of brain tissue loss.
• Affected regions in ALS include both motor and extramotor areas.
• DTI reveals a greater extent of abnormalities than volumetric analysis alone.