MRI model reveals microstructural brain changes linked to Huntington's disease

Researchers have demonstrated that a new MRI imaging model, known as SANDI, can detect subtle microstructural abnormalities within the brain linked to Huntington's disease. Published in eLife, this study represents a significant step forward in monitoring disease progression and evaluating potential treatments. The SANDI model, which stands for Soma and Neurite Density Imaging, analyzes how water molecules move inside cells to estimate their size and density, providing a more detailed picture of tissue changes than traditional MRI volume measurements.

Huntington's disease is a progressive neurodegenerative disorder that primarily affects the basal ganglia, a brain region responsible for movement, habit formation, and learning. While currently there are no disease-modifying therapies, clinical trials are underway, creating a need for sensitive imaging biomarkers to assess the impact of novel treatments.

SANDI can identify differences in the estimated density and size of neuronal bodies (somas) in the striatum, the brain region most affected by Huntington's disease. These differences, combined with age, could explain up to 63% of the brain tissue shrinkage observed in patients. Importantly, SANDI reveals these changes in the striatum but not in the thalamus, a finding that aligns with the known progression of neurodegeneration in Huntington's disease.

The study's senior author, Claudia Metzler-Baddeley, emphasizes that SANDI offers a complementary perspective to traditional volumetric measures, which are less sensitive to underlying neuropathological changes. The next steps include confirming these findings in larger, longitudinal studies and adapting the SANDI model for use in standard clinical MRI systems.

The researchers suggest that SANDI could also be applied to other neurodegenerative diseases such as Alzheimer's and Parkinson's.