Yuji Shen1, Ida M. Pu2
1Brain Research Imaging Centre, University of Edinburgh, Edinburgh, Scotland, United Kingdom; 2Department of Computing, Goldsmiths, University of London, London, United Kingdom
Hypercapnia and hyperoxia-induced BOLD contrasts were employed to measure the mean venous vessel size in human brain in response to hypercapnia and hyperoxia. A combined GE and SE sequence was used to acquire GE and SE signals simultaneously. The experimental paradigm consisted of two 3-minute blocks of breathing 6% CO2 or 100% O2 interleaved with three 2-minute blocks of breathing room air. The vessel size index q = R2*/R2 was calculated and then converted to the vessel radius. It was found that the mean venous vessel radii were larger in hypercapnia than in hyperoxia in both grey and white matter.