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Gray & white matter tissue contrast differentiates Mild Cognitive Impairment converters from non-converters
Angela L Jefferson1, Katherine A Gifford, Stephen Damon
1Vanderbilt Memory & Alzheimer's Center, Department of Neurology, Vanderbilt University Medical Center, 2525 West End Avenue, 12th Floor - Suite 1200, Nashville, TN, 37203, USA, angela.jefferson@vanderbilt.edu.
Abstract:
The clinical relevance of gray/white matter contrast ratio (GWR) in mild cognitive impairment (MCI) remains unknown. This study examined baseline GWR and 3-year follow-up diagnostic status in MCI. Alzheimer's Disease Neuroimaging Initiative MCI participants with baseline 1.5 T MRI and 3-year follow-up clinical data were included. Participants were categorized into two groups based on 3-year follow-up diagnoses: 1) non-converters (n = 69, 75 ± 7, 26 % female), and 2) converters (i.e., dementia at follow-up; n = 69, 75 ± 7, 30 % female) who were matched on baseline age and Mini-Mental State Examination scores. Groups were compared on FreeSurfer generated baseline GWR from structural images in which higher values represent greater tissue contrast. A general linear model, adjusting for APOE-status, scanner type, hippocampal volume, and cortical thickness, revealed that converters evidenced lower GWR values than non-converters (i.e., more degradation in tissue contrast; p = 0.03). Individuals with MCI who convert to dementia have lower baseline GWR values than individuals who remain diagnostically stable over a 3-year period, statistically independent of cortical thickness or hippocampal volume.
Insights
Gray/white matter contrast ratio (GWR) is a novel biomarker for mild cognitive impairment (MCI). Lower baseline GWR predicts conversion to dementia within three years, indicating significant neurodegeneration.
Area of Science:
- Neuroimaging
- Neurology
- Biomarkers
Background:
- The clinical significance of gray/white matter contrast ratio (GWR) in mild cognitive impairment (MCI) is not well understood.
- Investigating novel imaging biomarkers for predicting MCI progression is crucial for early diagnosis and intervention.
Purpose of the Study:
- To investigate the association between baseline gray/white matter contrast ratio (GWR) and the 3-year diagnostic conversion status in individuals with mild cognitive impairment (MCI).
Main Methods:
- Utilized baseline 1.5 T MRI data from Alzheimer's Disease Neuroimaging Initiative (ADNI) MCI participants with 3-year follow-up clinical data.
- Compared baseline GWR values between MCI participants who converted to dementia and those who remained stable, using a general linear model.
- Adjusted for covariates including APOE-status, scanner type, hippocampal volume, and cortical thickness.
Main Results:
- Individuals with MCI who converted to dementia within 3 years showed significantly lower baseline GWR values compared to non-converters (p=0.03).
- Lower GWR indicates greater degradation in tissue contrast, suggesting underlying neurodegeneration.
- This finding was statistically independent of cortical thickness and hippocampal volume.
Conclusions:
- Baseline gray/white matter contrast ratio (GWR) is a potential imaging biomarker for predicting the progression of mild cognitive impairment (MCI) to dementia.
- Lower GWR values in MCI patients may signify an increased risk of future dementia conversion.
- GWR offers valuable prognostic information beyond traditional volumetric measures like cortical thickness and hippocampal volume.
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