A hypercapnia-based normalization method for improved spatial localization of human brain activation with fMRI.
An issue in blood oxygenation level dependent contrast-based functional MRI is the accurate interpretation of the activation-induced signal changes. Hemodynamic factors other than activation-induced changes in blood oxygenation are known to contribute to the signal change magnitudes and dynamics, and therefore need to be accounted for or removed. In this paper, a general method for removal of effects other than activation-induced blood oxygenation changes from fMRI brain activation maps by the use of hypercapnic stress normalization is introduced. First, the effects of resting blood volume distribution across voxels on activation-induced BOLD-based fMRI signal changes are shown to be significant. Second, the effects of hypercapnia and hypoxia on resting and activation-induced signal changes are demonstrated. These results suggest that global hemodynamic stresses may be useful for non-invasive mapping of blood volume. Third, the normalization technique is demonstrated.
Bandettini
P A
PA
Medical College of Wisconsin, Biophysics Research Institute, Milwaukee 53226, USA. pab@post.its.mcw.edu
Wong
E C
EC
D001921:Brain / Q000033:anatomy & histology* / Q000098:blood supply / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D002245:Carbon Dioxide / Q000097:blood*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D010100:Oxygen / Q000097:blood
D002245:Carbon Dioxide; D010100:Oxygen