title: Effects of variable blast pressures on blood flow and oxygen saturation in rat brain as evidenced using MRI.
abstract: It has been recognized that primary blast waves may result in neurotrauma in soldiers in theater. A new type of contrast used in magnetic resonance imaging (MRI), susceptibility-weighted imaging (SWI), has been developed that is based on the different susceptibility levels in diverse tissues and can detect decreases in cerebral blood flow (CBF) using inferred oxygen saturation changes in tissue. In addition, a continuous arterial spin-labeled (ASL) MRI sequence was used as a direct measure of regional CBF within the brain tissue. Animals were subjected to whole-body blast exposures of various overpressures within a gas-driven shock tube. When exposed to low levels of overpressure, most rats demonstrated no obvious changes between pre- and postexposure in the conventional MR images. CBF changes measured by SWI and ASL were significantly higher for the overpressure exposed groups as compared to the sham group and tended to increase with pressure increases at the highest two pressures. In the hippocampus, all blast animals had a reduction in the CBF consistently in the range of 0-27%. In summary, low levels of primary blast pressure exposure demonstrated a significant physiologic effect to the brain up to 72 h postexposure.
authors.affiliation: Department of Biomedical Engineering, Wayne State University, Detroit, MI 48201, USA. cbir@wayne.edu
authors.forename: Cynthia
authors.initials: C
authors.lastname: Bir
authors.forename: Pamela
authors.initials: P
authors.lastname: Vandevord
authors.forename: Yimin
authors.initials: Y
authors.lastname: Shen
authors.forename: Waqar
authors.initials: W
authors.lastname: Raza
authors.forename: E Mark
authors.initials: EM
authors.lastname: Haacke
mesh_terms: D000818:Animals; D001753:Blast Injuries; D001930:Brain Injuries / Q000175:diagnosis*; D002560:Cerebrovascular Circulation; D004195:Disease Models, Animal; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010100:Oxygen / Q000097:blood*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow; D013113:Spin Labels
chemical_list: D013113:Spin Labels; D010100:Oxygen