title: Multimodal MR imaging of acute and subacute experimental traumatic brain injury: Time course and correlation with cerebral energy metabolites.
abstract: BACKGROUND
  Traumatic brain injury (TBI) is one of the leading causes of death and permanent disability world-wide. The predominant cause of death after TBI is brain edema which can be quantified by non-invasive diffusion-weighted magnetic resonance imaging (DWI).
  
  
  OBJECTIVE
  To provide a better understanding of the early onset, time course, spatial development, and type of brain edema after TBI and to correlate MRI data and the cerebral energy state reflected by the metabolite adenosine triphosphate (ATP).
  
  
  METHODS
  The spontaneous development of lateral fluid percussion-induced TBI was investigated in the acute (6 h), subacute (48 h), and chronic (7 days) phase in rats by MRI of quantitative T2 and apparent diffusion coefficient (ADC) mapping as well as perfusion was combined with ATP-specific bioluminescence imaging and histology.
  
  
  RESULTS
  An induced TBI led to moderate to mild brain damages, reflected by transient, pronounced development of vasogenic edema and perfusion reduction. Heterogeneous ADC patterns indicated a parallel, but mixed expression of vasogenic and cytotoxic edema. Cortical ATP levels were reduced in the acute and subacute phase by 13% and 27%, respectively, but were completely normalized at 7 days after injury.
  
  
  CONCLUSIONS
  The partial ATP reduction was interpreted to be partially caused by a loss of neurons in parallel with transient dilution of the regional ATP concentration by pronounced vasogenic edema. The normalization of energy metabolism after 7 days was likely due to infiltrating glia and not to recovery. The MRI combined with metabolite measurement further improves the understanding and evaluation of brain damages after TBI.
authors.affiliation: Department of Traumatology, Orthopedic Surgery and Sporttraumatology, Cologne-Merheim Medical Center (CMMC), University of Witten-Herdecke, Campus Cologne-Merheim, Germany ; Institute of Research in Operative Medicine, University of Witten-Herdecke, Campus Cologne-Merheim, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Maegele
authors.affiliation: Institute of Research in Operative Medicine, University of Witten-Herdecke, Campus Cologne-Merheim, Germany.
authors.forename: Ewa K
authors.initials: EK
authors.lastname: Stuermer
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, Hospital Gummerbach, Gummersbach, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Hoeffgen
authors.affiliation: In-vivo-NMR Laboratory, Max-Planck-Institute for Neurological Research, Cologne, Germany.
authors.forename: Ulla
authors.initials: U
authors.lastname: Uhlenkueken
authors.affiliation: Institute for Neurosurgical Research, Department of Neurosurgery, University of Saarland, Homburg, Germany.
authors.forename: Angelika
authors.initials: A
authors.lastname: Mautes
authors.affiliation: Institute of Research in Operative Medicine, University of Witten-Herdecke, Campus Cologne-Merheim, Germany.
authors.forename: Nadine
authors.initials: N
authors.lastname: Schaefer
authors.affiliation: Center for Neurosurgery, University of Cologne, Cologne, Germany.
authors.forename: Marcela
authors.initials: M
authors.lastname: Lippert-Gruener
authors.affiliation: FE Experimental Neurotraumatology, Department of Neurosurgery, Medical University Graz, Graz, Austria.
authors.forename: Ute
authors.initials: U
authors.lastname: Schaefer
authors.affiliation: In-vivo-NMR Laboratory, Max-Planck-Institute for Neurological Research, Cologne, Germany ; Department of Radiology, Leiden University Medical Center, Leiden, Netherlands.
authors.forename: Mathias
authors.initials: M
authors.lastname: Hoehn
keywords: ATP imaging; Traumatic brain injury; cytotoxic edema; magnetic resonance imaging (MRI); transient reduction of energy metabolism; vasogenic edema