title: CT perfusion-derived mean transit time of cortical brain has a negative correlation with the plasma level of Nitric Oxide after subarachnoid hemorrhage.
abstract: BACKGROUND
  Vasospasm of both large and small parenchymal arteries may contribute to the occurrence of delayed ischemic neurological deficits, and nitric oxide(NO) is an important mediators in the development of cerebral vasospasm after subarachnoid hemorrhage (SAH). We used a rabbit two-hemorrhage model to investigate changes in plasma NO after SAH, and the relationship between NO and brain microcirculation.
  
  
  METHODS
  SAH was induced in rabbits and a control group was sham operated. There were 32 rabbits in each group that survived the second operation, and they were randomly assigned to four groups of eight rabbits each for follow-up assessments on Days 1, 4, 7, or 14, respectively. Cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) were calculated at six regions of interest (ROIs): symmetrical areas of the frontal, parietal-occipital, and temporal lobes. Before the contrast CT scan, blood was drawn from the central artery of the ear for measurement of plasma NO.
  
  
  RESULTS
  In the control group, there was no difference in CBV, CBF, and MTT in the six ROIs, and plasma NO was unchanged. Compared to controls, in the SAH group, CBV decreased slightly in the six ROIs (P > 0.05), frontal lobe CBF decreased, MTT increased (P < 0.05, for both), and NO plasma levels were significantly lower (P < 0.01).
  
  
  CONCLUSIONS
  There was a significant correlation between the increase in MTT and the decrease in plasma NO (P < 0.05), We hypothesized that normalization of NO might have a positive influence on brain microcirculation following SAH.
authors.affiliation: Departments of Radiology, First Affiliated Hospital of China Medical University, 155 Nanjing N St, Shenyang, 110001, Liaoning Province, People's Republic of China.
authors.forename: Ruibin
authors.initials: R
authors.lastname: Zheng
authors.forename: Lei
authors.initials: L
authors.lastname: Qin
authors.forename: Songbai
authors.initials: S
authors.lastname: Li
authors.forename: Ke
authors.initials: K
authors.lastname: Xu
authors.forename: Haiyang
authors.initials: H
authors.lastname: Geng
mesh_terms: D000792:Angiography; D000818:Animals; D015415:Biomarkers / Q000097:blood; D001810:Blood Volume; D001921:Brain / Q000098:blood supply; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology; D004195:Disease Models, Animal; D005260:Female; D006439:Hemodynamics; D008297:Male; D008833:Microcirculation; D009569:Nitric Oxide / Q000097:blood*; D010477:Perfusion; D011817:Rabbits; D011897:Random Allocation; D013345:Subarachnoid Hemorrhage / Q000097:blood* / Q000000981:diagnostic imaging* / Q000503:physiopathology; D014057:Tomography, X-Ray Computed; D020301:Vasospasm, Intracranial / Q000503:physiopathology
chemical_list: D015415:Biomarkers; D009569:Nitric Oxide