A combined microdialysis and FDG-PET study of glucose metabolism in head injury
Microdialysis continuously monitors the chemistry of a small focal volume of the cerebral extracellular space. Positron emission tomography (PET) establishes metabolism of the whole brain but only for the scan’s duration. This study’s objective was to apply these techniques together, in patients with traumatic brain injury, to assess the relationship between microdialysis (extracellular glucose, lactate, pyruvate, and the lactate/pyruvate (L/P) ratio as a marker of anaerobic metabolism) and PET parameters of glucose metabolism using the glucose analogue [18F]-fluorodeoxyglucose (FDG). In particular, we aimed to determine the fate of glucose in terms of differential metabolism to pyruvate and lactate.
Materials and methods
Microdialysis catheters (CMA70 or CMA71) were inserted into the cerebral cortex of 17 patients with major head injury. Microdialysis was performed during FDG-PET scans with regions of interest for PET analysis defined by the location of the gold-tipped microdialysis catheter. Microdialysate analysis was performed on a CMA600 analyser.
There was significant linear relationship between the PET-derived parameter of glucose metabolism (regional cerebral metabolic rate of glucose; CMRglc) and levels of lactate (r = 0.778, p < 0.0001) and pyruvate (r = 0.799, p < 0.0001), but not with the L/P ratio.
The results suggest that in this population of patients, glucose was metabolised to both lactate and pyruvate, but was not associated with an increase in the L/P ratio. This suggests an increase in glucose metabolism to both lactate and pyruvate, as opposed to a shift towards anaerobic metabolism.
KeywordsMicrodialysis Positron emission tomography Cerebral metabolism Glucose Glycolysis Traumatic brain injury
- 8.Coles JP, Fryer TD, Smielewski P, Chatfield DA, Steiner LA, Johnston AJ, Downey SP, Williams GB, Aigbirhio F, Hutchinson PJ, Rice K, Carpenter TA, Clark JC, Pickard JD, Menon DK (2004) Incidence and mechanisms of cerebral ischemia in early clinical head injury. J Cereb Blood Flow Metab 24:202–211PubMedCrossRefGoogle Scholar
- 12.Enblad P, Valtysson J, Andersson J, Lilja A, Valind S, Antoni G, Langstrom B, Hillered L, Persson L (1996) Simultaneous intracerebral microdialysis and positron emission tomography in the detection of ischemia in patients with subarachnoid hemorrhage. J Cereb Blood Flow Metab 16:637–644PubMedCrossRefGoogle Scholar
- 21.Hutchinson PJ, Gupta AK, Fryer TF, Al-Rawi PG, Chatfield DA, Coles JP, O’Connell MT, Kett-White R, Minhas PS, Aigbirhio FI, Clark JC, Kirkpatrick PJ, Menon DK, Pickard JD (2002) Correlation between cerebral blood flow, substrate delivery, and metabolism in head injury: a combined microdialysis and triple oxygen positron emission tomography study. J Cereb Blood Flow Metab 22:735–745PubMedCrossRefGoogle Scholar
- 25.Lee JY, Kim YH, Koh JY (2001) Protection by pyruvate against transient forebrain ischemia in rats. J Neurosci 21:RC71Google Scholar
- 31.O’Connell MT, Seal A, Nortje J, Al-Rawi PG, Coles JP, Fryer TD, Menon DK, Pickard JD, Hutchinson PJ (2005) Glucose metabolism in traumatic brain injury: a combined microdialysis and [18F]-2-fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) study. Acta Neurochir Suppl 95:165–168PubMedCrossRefGoogle Scholar
- 38.Samuelsson C, Hillered L, Zetterling M, Enblad P, Hesselager G, Ryttlefors M, Kumlien E, Lewén A, Marklund N, Nilsson P, Salci K, Ronne-Engström E (2007) Cerebral glutamine and glutamate levels in relation to compromised energy metabolism: a microdialysis study in subarachnoid hemorrhage patients. J Cereb Blood Flow Metab 27:1309–1317PubMedCrossRefGoogle Scholar
- 43.Vespa P, Bergsneider M, Hattori N, Wu HM, Huang SC, Martin NA, Glenn TC, McArthur DL, Hovda DA (2005) Metabolic crisis without brain ischemia is common after traumatic brain injury: a combined microdialysis and positron emission tomography study. J Cereb Blood Flow Metab 25:763–774PubMedCrossRefGoogle Scholar