18F-Fluorodeoxyglucose Positron Emission Tomography Findings Are Not Related to Cognitive Functioning in Service Members with Remote History of Traumatic Brain Injury

Abstract Objective: Determine whether glucose uptake as measured by 18F-Fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging is associated with cognitive performance and mild neurocognitive disorder (MNCD) in active-duty service members with a history of mild traumatic brain injury (mTBI). Method: 287 patients with a history of mTBI underwent FDG-PET scans at rest and neuropsychological testing at the National Intrepid Center of Excellence at Walter Reed National Military Medical Center. Glucose uptake in bilateral frontal, parietal, occipital, and temporal lobes, and 58 cortical/cerebellar regions were correlated with seven neuropsychological composite scores, with and without relevant covariates. Results: Prior to correction for multiple comparisons, perceptual reasoning correlated with bilateral hippocampi glucose uptake (rs:.141-.165, ps<.03), processing speed was inversely related to glucose uptake in the left temporal lobe (r=-.134, p=.034), working memory was related to glucose uptake in the left parietal, temporal, and occipital lobes (rs:.128-.140, ps<.05). Partial correlations between cognition and the 56 cortical/cerebellar regions of interest (ROIs) were not significant after correction for multiple comparisons. Increased glucose uptake in the bilateral pericalcarine, left superior temporal, and right occipital, superior parietal, transverse temporal, precuneus, and lingual cortices was related to increased likelihood of MNCD (ORs:41.02-2263.7, ps<.05); however, did not survive correction for multiple comparisons. Conclusions: After correction for multiple comparisons, there was no significant relationship between regional glucose uptake and neurocognitive performance or MNCD. Glucose uptake as measured by FDG-PET is not related to cognitive performance in active-duty service members with a remote history of mTBI and may have limited clinical utility for these individuals.