title: Cerebral vascular response to hypercapnia: determination with perfusion MRI at 1.5 and 3.0 Tesla using a pulsed arterial spin labeling technique.
abstract: OBJECTIVE
  To compare the quantification of cerebral blood flow (CBF) at 1.5 and 3.0 Tesla, under normo- and hypercapnia, and to determine the cerebral vascular response (CVR) of gray matter (GM) to hypercapnia, a pulsed arterial spin labeling technique was used. Additionally, to improve GM CBF quantification a high-resolution GM-mask was applied.
  
  
  METHODS
  CBF was determined with the QUIPSS II with thin slice TI1 periodic saturation (Q2TIPS) sequence at 1.5 and 3.0 Tesla in the same group of eight subjects, both under normocapnia and hypercapnia. Absolute GM-CBF maps were calculated using a GM-mask obtained from a high-resolution structural scan by segmentation. The CVR to hypercapnia was derived from the quantitative GM-CBF maps.
  
  
  RESULTS
  For both field strengths, the GM-CBF was significantly higher under hypercapnia compared to normocapnia. For both conditions, there was no significant difference of GM-CBF for 1.5 and 3.0 Tesla; the same applies to the CVR, which was 4.3 and 4.5%/mmHg at 1.5 and 3.0 Tesla, respectively.
  
  
  CONCLUSIONS
  The method presented allows for the quantification of CBF and CVR in GM at the common clinical field strengths of 1.5 and 3.0 Tesla and could therefore be a useful tool to study these parameters under physiological and pathophysiological conditions.
authors.affiliation: Wellcome Department of Imaging Neuroscience, Institute of Neurology, University College London, London, UK. noeth@gsf.de
authors.forename: Ulrike
authors.initials: U
authors.lastname: Nöth
authors.forename: Guy E
authors.initials: GE
authors.lastname: Meadows
authors.forename: Futoshi
authors.initials: F
authors.lastname: Kotajima
authors.forename: Ralf
authors.initials: R
authors.lastname: Deichmann
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Corfield
authors.forename: Robert
authors.initials: R
authors.lastname: Turner
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D001921:Brain / Q000098:blood supply* / Q000473:pathology / Q000503:physiopathology*; D002536:Cerebral Arteries / Q000503:physiopathology; D002560:Cerebrovascular Circulation; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D011673:Pulsatile Flow; D013113:Spin Labels
chemical_list: D013113:Spin Labels