Comparison of the effects of independently-controlled end-tidal PCO2 and PO2 on blood oxygen level–dependent (BOLD) MRI
✍ Scribed by Eitan Prisman; Marat Slessarev; Jay Han; Julien Poublanc; Alexandra Mardimae; Adrian Crawley; Joseph Fisher; David Mikulis
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 258 KB
- Volume
- 27
- Category
- Article
- ISSN
- 1053-1807
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✦ Synopsis
Abstract
Purpose
To assess the effect of changes in end‐tidal partial pressure of O~2~ (PETO~2~) on cerebrovascular reactivity (CVR) estimated from changes in blood oxygen level–dependent (BOLD) signal during cyclic changes in end‐tidal partial pressure of CO~2~ (PETCO~2~).
Materials and Methods
BOLD response to fixed cyclic step changes in PETCO~2~ (range = 30.4–48.8 mmHg) and PETO~2~ (range = 100.6–444.0 mmHg) was studied in four healthy volunteers.
Results
The BOLD reactivity to PETCO~2~ and PETO~2~ were 0.283 (0.188–0.379) (median, range) and 0.004 (0.003–0.006)%/mmHg, respectively, in the whole brain; 0.438 (0.382–0.614) vs. 0.006 (0.004–0.009)%/mmHg, respectively, in the gray matter; and 0.075 (0.065–0.093) vs. 0.002 (0.001–0.002)%/mmHg, respectively, in the white matter.
Conclusion
The BOLD reactivity to PETO~2~ was much smaller than that to PETCO~2~. However, BOLD reactivity can be significantly distorted by CO~2~‐induced changes in PETO~2~. We conclude that PETO~2~ should be carefully controlled during studies that use BOLD reactivity as an indicator of CVR. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.