A hypercapnia-based normalization method for improved spatial localization of human brain activation with fMRI. Bandettini, P A & Wong, E C NMR in Biomedicine, 10(4-5):197--203, June, 1997.
A hypercapnia-based normalization method for improved spatial localization of human brain activation with fMRI [link]Paper  abstract   bibtex   
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.
@article{bandettini_hypercapnia-based_1997,
	title = {A hypercapnia-based normalization method for improved spatial localization of human brain activation with {fMRI}},
	volume = {10},
	issn = {0952-3480},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/9430348},
	abstract = {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.},
	number = {4-5},
	urldate = {2009-02-13},
	journal = {NMR in Biomedicine},
	author = {Bandettini, P A and Wong, E C},
	month = jun,
	year = {1997},
	pmid = {9430348},
	keywords = {ASL, BOLD, hypercapnia, calibratedBOLD, CO2},
	pages = {197--203},
	file = {bandettini1997.pdf:/Users/nickb/Zotero/storage/TWGW8IWM/bandettini1997.pdf:application/pdf;PubMed Snapshot:/Users/nickb/Zotero/storage/AG78NKN3/entrez.html:text/html}
}

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