title: Magnetic resonance imaging studies of age-dependent responses to scaled focal brain injury in the piglet.
abstract: OBJECTIVE
  Whether the brain differs in its response to traumatic injury as a function of age remains unclear. To further investigate the age-dependent response of the brain to mechanical trauma, a cortical contusion model scaled for brain growth during maturation was used to study the evolution of injury over time as demonstrated on serial magnetic resonance (MR) imaging studies in piglets of different ages.
  
  
  METHODS
  Sixteen Yorkshire piglets received scaled cortical contusions. Animals were either 5 days (six animals), 1 month (five animals), or 4 months (five animals) of age at injury. These ages correspond developmentally to human infants, toddlers, and early adolescents, respectively. Serial MR imaging examinations, including fluid-attenuated inversion-recovery and T1-, T2-, and diffusion-weighted sequences were performed at 24 hours, 1 week, and 1 month after injury. Lesions were quantified and expressed as a ratio of the lesion volume divided by the volume of the uninjured hemisphere for each animal and each MR sequencing. Differences in relative lesion volume among the varied ages at a single time point and in lesion volume over time at each age were compared. In addition, the relationship between age and evolution of injury were analyzed using a two-compartment mathematical model. Histological features were examined at 1 month postinjury. Despite comparable injury inputs, the youngest animals had lesions whose volumes peaked earlier and resolved more quickly than those in older animals. The intermediate-age piglets (toddler) had the most pronounced swelling of any age group, and the oldest piglets (adolescent) had the latest peak in lesion volume.
  
  
  CONCLUSIONS
  Scaled cortical contusions in piglets demonstrated age-dependent differences in injury response, both in magnitude and time course. These observations may shed light on development-related trauma response in the gyrencephalic brain.
authors.affiliation: Department of Neurosurgery, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03756, USA. Ann-Christine.Duhaime@Hitchcock.org
authors.forename: Ann-Christine
authors.initials: AC
authors.lastname: Duhaime
authors.forename: Jill V
authors.initials: JV
authors.lastname: Hunter
authors.forename: Loretta L
authors.initials: LL
authors.lastname: Grate
authors.forename: Anje
authors.initials: A
authors.lastname: Kim
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Golden
authors.forename: Eugene
authors.initials: E
authors.lastname: Demidenko
authors.forename: Christine
authors.initials: C
authors.lastname: Harris
mesh_terms: D000367:Age Factors; D000818:Animals; D001930:Brain Injuries / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging; D023421:Models, Animal; D013552:Swine