Test-Retest Stability of Calibrated BOLD-fMRI in HIV- and HIV+ Subjects. Ances, B., Vaida, F., Ellis, R., & Buxton, R. NeuroImage.
Test-Retest Stability of Calibrated BOLD-fMRI in HIV- and HIV+ Subjects [link]Paper  doi  abstract   bibtex   
Subject performance, scanner hardware, or biological factors can affect single session neuroimaging measures. Stability studies using calibrated blood oxygenation level dependent functional magnetic resonance imaging (BOLD-fMRI) have been performed in health but not disease. We utilized calibrated BOLD-fMRI to determine the effects of HIV on neurovascular coupling. 6 clinically stable HIV-infected patients (HIV+) and 10 seronegative controls (HIV-) were scanned at two separate sessions approximately 3 months apart. Both mild hypercapnia (5% CO2) exposure and a visual functional activation task were performed. Intra-class correlation coefficients (ICC) and inter-subject variance were determined for calibrated BOLD-fMRI measures (baseline cerebral blood flow (CBF), functional CBF, BOLD, and cerebral metabolic rate of oxygen consumption (CMRO2) changes) for HIV+ and HIV- subjects. The two groups did not differ in age, sex, or education. HIV+ subjects had lower mean baseline CBF (p \textless 0.04, Cohen's d = -1.07) and functional BOLD responses (p \textless 0.001, Cohen's d = -2.47) and a trend towards a decrease in mean functional CBF responses (p = 0.07, Cohen's d = -0.92) despite similar mean functional CMRO2 changes (p = 0.71, Cohen's d = 0.19). The stability of each calibrated BOLD-fMRI measure, as assessed by ICC, was significantly lower for HIV+ subjects. In addition, HIV+ participants had greater inter-subject variability for baseline CBF (p \textless 0.02), functional BOLD (p \textless 0.001), CBF (p \textless 0.001), and CMRO2 (p \textless 0.002) responses. Our results demonstrate that calibrated BOLD-fMRI measures have excellent stability within healthy controls. In contrast, these values have greater variability in clinically stable HIV+ subjects and may reflect alterations in coupling between CBF and CMRO2 with disease.
@article{ances_test-retest_nodate,
	title = {Test-{Retest} {Stability} of {Calibrated} {BOLD}-{fMRI} in {HIV}- and {HIV}+ {Subjects}},
	volume = {In Press, Accepted Manuscript},
	issn = {1053-8119},
	url = {http://www.sciencedirect.com/science/article/B6WNP-515SRFP-8/2/dc42524aacbbe6d4195604113ff26087},
	doi = {10.1016/j.neuroimage.2010.09.081},
	abstract = {Subject performance, scanner hardware, or biological factors can affect single session neuroimaging measures. Stability studies using calibrated blood oxygenation level dependent functional magnetic resonance imaging (BOLD-fMRI) have been performed in health but not disease. We utilized calibrated BOLD-fMRI to determine the effects of HIV on neurovascular coupling. 6 clinically stable HIV-infected patients (HIV+) and 10 seronegative controls (HIV-) were scanned at two separate sessions approximately 3 months apart. Both mild hypercapnia (5\% CO2) exposure and a visual functional activation task were performed. Intra-class correlation coefficients (ICC) and inter-subject variance were determined for calibrated BOLD-fMRI measures (baseline cerebral blood flow (CBF), functional CBF, BOLD, and cerebral metabolic rate of oxygen consumption (CMRO2) changes) for HIV+ and HIV- subjects. The two groups did not differ in age, sex, or education. HIV+ subjects had lower mean baseline CBF (p {\textless} 0.04, Cohen's d = -1.07) and functional BOLD responses (p {\textless} 0.001, Cohen's d = -2.47) and a trend towards a decrease in mean functional CBF responses (p = 0.07, Cohen's d = -0.92) despite similar mean functional CMRO2 changes (p = 0.71, Cohen's d = 0.19). The stability of each calibrated BOLD-fMRI measure, as assessed by ICC, was significantly lower for HIV+ subjects. In addition, HIV+ participants had greater inter-subject variability for baseline CBF (p {\textless} 0.02), functional BOLD (p {\textless} 0.001), CBF (p {\textless} 0.001), and CMRO2 (p {\textless} 0.002) responses. Our results demonstrate that calibrated BOLD-fMRI measures have excellent stability within healthy controls. In contrast, these values have greater variability in clinically stable HIV+ subjects and may reflect alterations in coupling between CBF and CMRO2 with disease.},
	urldate = {2010-10-07},
	journal = {NeuroImage},
	author = {Ances, Beau and Vaida, Florin and Ellis, Ronald and Buxton, Richard},
	keywords = {calibratedBOLD},
	file = {ances2010.pdf:/Users/nickb/Zotero/storage/9I3ZM6E2/ances2010.pdf:application/pdf;ScienceDirect Snapshot:/Users/nickb/Zotero/storage/3CS7JTSN/science.html:text/html}
}

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