Selective Metabolic Reduction in Gray Matter Acutely following Human Traumatic Brain Injury

Abstract

The aim of this study was to determine whether the apparent loss of overall gray-white matter contrast (GM/WM) seen on FDG-PET imaging reflects the differential changes of glucose metabolic rate (CMRglc) in cortical gray mater (GM) and subcortical white mater (WM) following TBI. The clinical significance of the CMRglc GM-to-WM ratio was also evaluated. Nineteen normal volunteers and 14 TBI patients were studied. Each subject had a quantitative FDG-PET, a quantitative H215O-PET and a MR scan acutely following TBI. Stabilities of the global and regional FDG lumped constants (LC) were studied. Parametric images (pixel unit: mg/min/100g) of FDG uptake rate (CURFDG) and CMRglc were generated. The changes of CMR(glc) in whole brain, GM and WM were studied separately by using a MRI-segmentation-based technique. The GM-to-WM ratios of both CURFDG and CMRglc images were significantly (p < 0.001) decreased (>31%) in TBI patients. The global LC value reduced significantly (p < 0.01) in TBI patients. The CMRglc decreased significantly (p < 0.001) in GM but not in WM (p > 0.1). Kinetic analysis revealed significant (p < 0.001) decrease of GM hexokinase activity in TBI patients. The GM-to-WM ratios of CMRglc correlated (r = 0.64) with the initial Glasgow Coma Score (GCS) of TBI patients. The patients with higher CMRglc GM-to-WM ratios (>1.54) showed good recovery 12 months after TBI. There was a selective CMRglc reduction in cortical GM following TBI. The pathophysiological basis for the reduction in GM-to-WM CMRglc ratio seen on FDG-PET imaging following TBI remains to be determined.

Metabolic Crisis without Brain Ischemia is Common after Traumatic Brain Injury: A Combined Microdialysis and Positron Emission Tomography Study

“…Both reductions and increases in the OGR have been shown to occur after TBI in the current study. This alteration of OGR was previously characterized by Wu et al (2004). OGR is the stochiometric relationship between oxidative to glucose metabolism, which is normally in a ratio of approximately 6.…”

“…Positron emission tomography was performed using a quantitative method previously described (Bergsneider et al, 2001;Wu et al, 2004). Patients were placed into the scanner and physiological monitoring of ICP, end-tidal CO 2 , arterial blood gases, arterial blood pressure, continuous electroencephalography, core temperature, and heart rate wes monitored using a portable intensive care unit (ICU) monitoring system.…”

Functionally-Detected Cognitive Impairment in High School Football Players without Clinically-Diagnosed Concussion

“…[43][44][45] To better evaluate the structure-function relationships that cause neurological damage, it will be essential to expand the range of neurological testing done within the MRI, and to add structural assessments such as diffusion tensor imaging, 46 and susceptibility-weighted imaging 47 modalities. In addition, better characterization of the mechanical insults, and the complex, heterogeneous effects they have on the brain itself, must be developed.…”

Common data elements in radiologic imaging of traumatic brain injury

“…These imaging modalities do not image the same physiology; SPECT images perfusion and PET images glucose metabolism. In normally functioning brain tissue, these processes are coupled; however, these processes may become uncoupled in TBI (92)(93)(94). Additionally, metabolic crisis following TBI is proposed to occur via mechanisms unrelated to brain ischemia (90).…”