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.
Wu
Hsiao-Ming
HM
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
Huang
Sung-Cheng
SC
Hattori
Naoya
N
Glenn
Thomas C
TC
Vespa
Paul M
PM
Yu
Chin-Lung
CL
Hovda
David A
DA
Phelps
Michael E
ME
Bergsneider
Marvin
M
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