Cerebral vascular response to hypercapnia: determination with perfusion MRI at 1.5 and 3.0 Tesla using a pulsed arterial spin labeling technique.
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.
Nöth
Ulrike
U
Wellcome Department of Imaging Neuroscience, Institute of Neurology, University College London, London, UK. noeth@gsf.de
Meadows
Guy E
GE
Kotajima
Futoshi
F
Deichmann
Ralf
R
Corfield
Douglas R
DR
Turner
Robert
R
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
D013113:Spin Labels