Lirong Yan1, Yan Zhuo1, Bo Wang1,
Cheng Li2, Jiongjiong Wang2
1Institute of Biophysics, Chinese
Academy of Sciences, Beijing, China; 2Department of Radiology,
University of Pennsylvania, Philadelphia, PA, United States
We
investigated the relationship between in vivo measurement of venous blood T1
and BOLD signal changes during visual stimulation in two groups of young and
elderly subjects. There was a significant negative correlation between venous
blood T1 and BOLD activation across subjects. Upon including venous blood T1
as a covariate, the differences in BOLD activation between the two age groups
weakened, suggesting that aging effects on BOLD fMRI may be partly attributed
to baseline hematocrit variations.