title: Imaging of an inflammatory injury in the newborn rat brain with photoacoustic tomography.
abstract: BACKGROUND
  The precise assessment of cerebral saturation changes during an inflammatory injury in the developing brain, such as seen in periventricular leukomalacia, is not well defined. This study investigated the impact of inflammation on locoregional cerebral oxygen saturation in a newborn rodent model using photoacoustic imaging.
  
  
  METHODS
  1 mg/kg of lipopolysaccharide(LPS) diluted in saline or saline alone was injected under ultrasound guidance directly in the corpus callosum of P3 rat pups. Coronal photoacoustic images were carried out 24 h after LPS exposure. Locoregional oxygen saturation (SO2) and resting state connectivity were assessed in the cortex and the corpus callosum. Microvasculature was then evaluated on cryosection slices by lectin histochemistry.
  
  
  RESULTS
  Significant reduction of SO2 was found in the corpus callosum; reduced SO2 was also found in the cortex ipsilateral to the injection site. Seed-based functional connectivity analysis showed that bilateral connectivity was not affected by LPS exposure. Changes in locoregional oxygen saturation were accompanied by a significant reduction in the average length of microvessels in the left cortex but no differences were observed in the corpus callosum.
  
  
  CONCLUSIONS
  Inflammation in the developing brain induces marked reduction of locoregional oxygen saturation, predominantly in the white matter not explained by microvascular degeneration. The ability to examine regional saturation offers a new way to monitor injury and understand physiological disturbance non-invasively.
authors.affiliation: Department of Electrical Engineering, École Polytechnique de Montréal, Montréal, Québec, Canada ; Montreal Heart Institute, Montréal, Québec, Canada.
authors.forename: Edgar
authors.initials: E
authors.lastname: Guevara
authors.affiliation: Department of Electrical Engineering, École Polytechnique de Montréal, Montréal, Québec, Canada ; Montreal Heart Institute, Montréal, Québec, Canada.
authors.forename: Romain
authors.initials: R
authors.lastname: Berti
authors.affiliation: Research Center-CHU Ste-Justine, Department of Pediatrics, Université de Montréal, Montréal, Québec, Canada.
authors.forename: Irène
authors.initials: I
authors.lastname: Londono
authors.affiliation: Research Center-CHU Ste-Justine, Department of Pediatrics, Université de Montréal, Montréal, Québec, Canada.
authors.forename: Ningshi
authors.initials: N
authors.lastname: Xie
authors.affiliation: Geriatric Institute Research Center, Université de Montréal, Montréal, Québec, Canada ; Department of Computer Science and Operations Research (DIRO), Université de Montréal, Montréal, Québec, Canada.
authors.forename: Pierre
authors.initials: P
authors.lastname: Bellec
authors.affiliation: Department of Electrical Engineering, École Polytechnique de Montréal, Montréal, Québec, Canada ; Montreal Heart Institute, Montréal, Québec, Canada.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Lesage
authors.affiliation: Montreal Heart Institute, Montréal, Québec, Canada ; Research Center-CHU Ste-Justine, Department of Pediatrics, Université de Montréal, Montréal, Québec, Canada.
authors.forename: G A
authors.initials: GA
authors.lastname: Lodygensky
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001930:Brain Injuries / Q000473:pathology*; D061088:Photoacoustic Techniques / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014054:Tomography / Q000379:methods*