title: Brain tissue water uptake after middle cerebral artery occlusion assessed with CT.
abstract: OBJECTIVE
  To study whether computed tomography (CT) can measure the water content of early ischemic edema.
  
  
  METHODS
  The authors obtained cranial CT in 5 groups of rats subjected to 1 hour (n = 8), 2 hours (n = 11), 3 hours (n = 13), 4 hours (n = 13), or 6 hours (n = 14) of right middle cerebral artery (MCA) occlusion. Immediately after CT, the authors removed the rats' brains and determined tissue water content by the dry-wet weight method. They correlated brain x-ray attenuation with brain tissue water content.
  
  
  RESULTS
  Mean brain tissue water content remained constant in the nonischemic left hemispheres at 77.9% +/- 0.6% and increased up to 79.3% +/- 1.0% in the right hemispheres after 6 hours of permanent right MCA occlusion. X-ray attenuation remained constant in the left hemispheres at 75.6 + 2.2 Hounsfield units (HU) and decreased to 71.7 +/- 3.4 HU in the right hemispheres after 6 hours of right MCA occlusion. The decrease in x-ray attenuation correlated significantly with the increase in ischemic brain tissue water content (y = 217.3 - 1.8x x; r = .55, P < .0001). That means that a 1% increase in hemispheric tissue water content causes a decrease in x-ray attenuation of 1.8 HU.
  
  
  CONCLUSIONS
  After MCA occlusion, immediate brain tissue net water uptake is associated with a decrease in x-ray attenuation. CT can monitor ischemic edema in an acute stroke.
authors.affiliation: Department of Neuroradiology, University of Dresden, Dresden, Germany.
authors.forename: Imanuel
authors.initials: I
authors.lastname: Dzialowski
authors.forename: Johannes
authors.initials: J
authors.lastname: Weber
authors.forename: Arnd
authors.initials: A
authors.lastname: Doerfler
authors.forename: Michael
authors.initials: M
authors.lastname: Forsting
authors.forename: Rüdiger
authors.initials: R
authors.lastname: von Kummer
mesh_terms: D000818:Animals; D001834:Body Water / Q000378:metabolism*; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism*; D002545:Brain Ischemia / Q000000981:diagnostic imaging / Q000209:etiology / Q000378:metabolism; D020244:Infarction, Middle Cerebral Artery / Q000000981:diagnostic imaging* / Q000378:metabolism; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D014057:Tomography, X-Ray Computed