A multi-compartmental SE-BOLD interpretation for stimulus-related signal changes in diffusion-weighted functional MRI. Kershaw, J., Tomiyasu, M., Kashikura, K., Hirano, Y., Nonaka, H., Hirano, M., Ikehira, H., Kanno, I., & Obata, T. NMR in Biomedicine, 9999(9999):n/a, 2009.
A multi-compartmental SE-BOLD interpretation for stimulus-related signal changes in diffusion-weighted functional MRI [link]Paper  doi  abstract   bibtex   
A new interpretation is proposed for stimulus-induced signal changes in diffusion-weighted functional MRI. T2-weighted spin-echo echo-planar images were acquired at different diffusion-weightings while visual stimulation was presented to human volunteers. The amplitudes of the positive stimulus-correlated response and post-stimulus undershoot (PSU) in the functional time-courses were found to follow different trends as a function of b-value. Data were analysed using a three-compartment signal model, with one compartment being purely vascular and the other two dominated by fast- and slow-diffusing molecules in the brain tissue. The diffusion coefficients of the tissue were assumed to be constant throughout the experiments. It is shown that the stimulus-induced signal changes can be decomposed into independent contributions originating from each of the three compartments. After decomposition, the fast-diffusion phase displays a substantial PSU, while the slow-diffusion phase demonstrates a highly reproducible and stimulus-correlated time-course with minimal undershoot. The decomposed responses are interpreted in terms of the spin-echo blood oxygenation level dependent (SE-BOLD) effect, and it is proposed that the signal produced by fast- and slow-diffusing molecules reflect a sensitivity to susceptibility changes in arteriole/venule- and capillary-sized vessels, respectively. This interpretation suggests that diffusion-weighted SE-BOLD imaging may provide subtle information about the haemodynamic and neuronal responses. Copyright � 2009 John Wiley & Sons, Ltd.
@article{kershaw_multi-compartmental_2009,
	title = {A multi-compartmental {SE}-{BOLD} interpretation for stimulus-related signal changes in diffusion-weighted functional {MRI}},
	volume = {9999},
	url = {http://dx.doi.org/10.1002/nbm.1391},
	doi = {10.1002/nbm.1391},
	abstract = {A new interpretation is proposed for stimulus-induced signal changes in diffusion-weighted functional MRI. T2-weighted spin-echo echo-planar images were acquired at different diffusion-weightings while visual stimulation was presented to human volunteers. The amplitudes of the positive stimulus-correlated response and post-stimulus undershoot (PSU) in the functional time-courses were found to follow different trends as a function of b-value. Data were analysed using a three-compartment signal model, with one compartment being purely vascular and the other two dominated by fast- and slow-diffusing molecules in the brain tissue. The diffusion coefficients of the tissue were assumed to be constant throughout the experiments. It is shown that the stimulus-induced signal changes can be decomposed into independent contributions originating from each of the three compartments. After decomposition, the fast-diffusion phase displays a substantial PSU, while the slow-diffusion phase demonstrates a highly reproducible and stimulus-correlated time-course with minimal undershoot. The decomposed responses are interpreted in terms of the spin-echo blood oxygenation level dependent (SE-BOLD) effect, and it is proposed that the signal produced by fast- and slow-diffusing molecules reflect a sensitivity to susceptibility changes in arteriole/venule- and capillary-sized vessels, respectively. This interpretation suggests that diffusion-weighted SE-BOLD imaging may provide subtle information about the haemodynamic and neuronal responses. Copyright � 2009 John Wiley \& Sons, Ltd.},
	number = {9999},
	urldate = {2009-05-06},
	journal = {NMR in Biomedicine},
	author = {Kershaw, Jeff and Tomiyasu, Moyoko and Kashikura, Kenichi and Hirano, Yoshiyuki and Nonaka, Hiroi and Hirano, Masaya and Ikehira, Hiroo and Kanno, Iwao and Obata, Takayuki},
	year = {2009},
	keywords = {theory, BOLD, balloonmodel, diffusion},
	pages = {n/a},
	file = {kershaw2009.pdf:/Users/nickb/Zotero/storage/C7WPPUQQ/kershaw2009.pdf:application/pdf;Wiley InterScience \:\: JOURNALS \:\: NMR in Biomedicine:/Users/nickb/Zotero/storage/UH2G9DGF/abstract.html:text/html}
}

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