title: A magnetic resonance imaging grading system for subarachnoid hemorrhage severity in a rat model.
abstract: BACKGROUND
  The endovascular perforation model of subarachnoid hemorrhage (SAH) has a large variation in outcomes. This may reflect differences in the SAH size.
  
  
  METHODS
  Magnetic resonance imaging (MRI) was performed 24h after endovascular perforation in adult male (n=58) and female (n=58) rats. Rats were divided into five grades according to MRI characteristics: grade 0: no SAH or intraventricular hemorrhage (IVH); grade 1: minimal or thin SAH without IVH; grade 2: minimal or thin SAH with IVH; grade 3: thick SAH without IVH; grade 4: thick SAH with IVH. We investigated whether MRI grading scale reflected severity of SAH (determined post mortem) and neurological score.
  
  
  RESULTS
  There was a strong correlation between MRI grading scale and current SAH grading scale (P<0.01) and neurological score (P<0.01) in male rats. In female rats, there was also a strong correlation between MRI grading scale and SAH grading scale (P<0.01) but not with neurological score (P=0.24).
  
  
  METHODS
  The current grading system is based on the amount of SAH and needs animal euthanasia to evaluate SAH severity. There is no useful grading system to classify severity of SAH without decapitating animals.
  
  
  CONCLUSIONS
  We demonstrated a correlation between the MRI grading scale and the current SAH grading scale in an endovascular perforation rat model. The MRI grading scale allows evaluation of SAH severity without euthanizing animals.
authors: Department of Neurosurgery, University of Michigan, Ann Arbor, MI, USA.
authors: Hajime
authors: H
authors: Shishido
authors: Department of Neurosurgery, University of Michigan, Ann Arbor, MI, USA.
authors: Yusuke
authors: Y
authors: Egashira
authors: Department of Neurosurgery, University of Michigan, Ann Arbor, MI, USA.
authors: Shuichi
authors: S
authors: Okubo
authors: Department of Neurosurgery, University of Michigan, Ann Arbor, MI, USA.
authors: Haining
authors: H
authors: Zhang
authors: Department of Neurosurgery, University of Michigan, Ann Arbor, MI, USA.
authors: Ya
authors: Y
authors: Hua
authors: Department of Neurosurgery, University of Michigan, Ann Arbor, MI, USA.
authors: Richard F
authors: RF
authors: Keep
authors: Department of Neurosurgery, University of Michigan, Ann Arbor, MI, USA. Electronic address: guohuaxi@umich.edu.
authors: Guohua
authors: G
authors: Xi
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009460:Neurologic Examination; D051381:Rats; D017207:Rats, Sprague-Dawley; D012720:Severity of Illness Index; D013345:Subarachnoid Hemorrhage / Q000175:diagnosis / Q000401:mortality / Q000473:pathology*
keywords: Endovascular perforation; Magnetic resonance imaging; Rat; Subarachnoid hemorrhage