title: Diffusion magnetic resonance imaging study of a rat hippocampal slice model for acute brain injury.
abstract: Diffusion magnetic resonance imaging (MRI) provides a surrogate marker of acute brain pathology, yet few studies have resolved the evolution of water diffusion changes during the first 8 hours after acute injury, a critical period for therapeutic intervention. To characterize this early period, this study used a 17.6-T wide-bore magnet to measure multicomponent water diffusion at high b-values (7 to 8,080 s/mm(2)) for rat hippocampal slices at baseline and serially for 8 hours after treatment with the calcium ionophore A23187. The mean fast diffusing water fraction (Ffast) progressively decreased for slices treated with 10-microM/L A23187 (-20.9 +/- 6.3% at 8 hours). Slices treated with 50-micromol/L A23187 had significantly reduced Ffast 80 minutes earlier than slices treated with 10-microM/L A23187 (P < 0.05), but otherwise, the two doses had equivalent effects on the diffusion properties of tissue water. Correlative histologic analysis showed dose-related selective vulnerability of hippocampal pyramidal neurons (CA1 > CA3) to pathologic swelling induced by A23187, confirming that particular intravoxel cell populations may contribute disproportionately to water diffusion changes observed by MRI after acute brain injury. These data suggest diffusion-weighted images at high b-values and the diffusion parameter Ffast may be highly sensitive correlates of cell swelling in nervous issue after acute injury.
authors.affiliation: Department of Neuroscience, Evelyn F. and William McKnight Brain Institute, University of Florida, Gainesville, Florida 32610, USA. tms@mbi.ufl.edu
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Shepherd
authors.forename: Peter E
authors.initials: PE
authors.lastname: Thelwall
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Blackband
authors.forename: Brian R
authors.initials: BR
authors.lastname: Pike
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Hayes
authors.forename: Edward D
authors.initials: ED
authors.lastname: Wirth
mesh_terms: D000208:Acute Disease; D000818:Animals; D001930:Brain Injuries / Q000473:pathology*; D002545:Brain Ischemia / Q000473:pathology*; D000001:Calcimycin / Q000494:pharmacology; D004058:Diffusion; D038524:Diffusion Magnetic Resonance Imaging; D004195:Disease Models, Animal; D004487:Edema / Q000473:pathology; D006624:Hippocampus / Q000293:injuries* / Q000473:pathology*; D007476:Ionophores / Q000494:pharmacology; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000473:pathology; D009924:Organ Culture Techniques; D051381:Rats; D020318:Rats, Long-Evans
chemical_list: D007476:Ionophores; D000001:Calcimycin