Structural MRI profiles in chronic traumatic encephalopathy and Alzheimer's disease

Date
2022
DOI
Authors
Mosaheb, Sydney
Version
OA Version
Citation
Abstract
Chronic Traumatic Encephalopathy (CTE) is a neurodegenerative disease that cannot be diagnosed during life in part due to lack of validated biomarkers. Alzheimer’s disease (AD) is a similar neurodegenerative disease to CTE, which has validated biomarkers to diagnosis this disease during life. Structural magnetic resonance imaging (MRI) is an important tool in the clinical evaluation and diagnosis of neurodegenerative diseases, including AD. A previous study characterized the structural MRI patterns of CTE via comparison to participants with normal cognition. While that study was a key first step in establishing structural MRI patterns of CTE, the study however did not include a disease comparison group. The objective of this study was to establish specificity of MRI profiles in CTE by comparing structural MRI patterns between CTE and AD. MRI scans were accessed via medical record request for 63 brain donors with autopsy confirmed CTE, 7 brain donors with neuropathologically confirmed AD and 28 participants with AD dementia who did not have neuropathologically confirmed AD. These were combined to form the AD group. The participants were all male and >60 years. Three neuroradiologists performed visual ratings of MRIs, and these individuals were blinded to the diagnostic groups. To rate regional atrophy on T1 sequences, and microvascular disease on T2, FLAIR and SWI, an established 5-point scale (0=absent, 4=severe) was used. Presence of cavum septum pellucidum (CSP) was rated. Brain donors with CTE had significantly greater atrophy in the anterior temporal lobe lobes (mean diff= 1.01, 95% CI=0.08-1.94, p=0.04) and 5.2X increased odds for having a CSP compared to the AD group. There were no statistically significant differences in the orbito-frontal cortex, dorsolateral frontal cortex, superior frontal cortex, parietal-occipital lobes, and the MTL. Ventricular enlargement and microvascular disease were not significantly different. However, the CTE group had greater atrophy in the frontal regions, including an approx.1 unit (on the 0-5 scale) higher severity rating for dorsolateral frontal cortex, whereas the AD group had greater atrophy in the posterior regions. The estimated effects were in the hypothesized direction, however, to detect small to medium effect sizes a larger sample is needed. Structural MRI could potentially be used as a diagnostic tool for CTE during life.
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