Selective metabolic reduction in gray matter acutely following human traumatic brain injury.
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.
Department of Molecular and Medical Pharmacology, UCLA Brain Injury Research Center, David Geffen School of Medicine at UCLA, Los Angeles, California, USA. cwu@mednet.ucla.edu
Hsiao-Ming
HM
Wu
Sung-Cheng
SC
Huang
Naoya
N
Hattori
Thomas C
TC
Glenn
Paul M
PM
Vespa
Chin-Lung
CL
Yu
David A
DA
Hovda
Michael E
ME
Phelps
Marvin
M
Bergsneider
D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001930:Brain Injuries / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000473:pathology; D002540:Cerebral Cortex / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000473:pathology; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D019275:Radiopharmaceuticals; D014055:Tomography, Emission-Computed / Q000379:methods*
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18