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Investigating the field-dependence of the Davis model: Calibrated fMRI at 1.5, 3 and 7 T

Hare, Hannah V.; Blockley, Nicholas P.; Gardener, Alexander G.; Clare, Stuart; Bulte, Daniel P.


Hannah V. Hare

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Assistant Professor

Alexander G. Gardener

Stuart Clare

Daniel P. Bulte


Gas calibrated fMRI in its most common form uses hypercapnia in conjunction with the Davis model to quantify relative changes in the cerebral rate of oxygen consumption (CMRO2) in response to a functional stimulus. It is most commonly carried out at 3 T but, as 7 T research scanners are becoming more widespread and the majority of clinical scanners are still 1.5 T systems, it is important to investigate whether the model used remains accurate across this range of field strengths. Ten subjects were scanned at 1.5, 3 and 7 T whilst performing a bilateral finger-tapping task as part of a calibrated fMRI protocol, and the results were compared to a detailed signal model. Simulations predicted an increase in value and variation in the calibration parameter M with field strength. Two methods of defining experimental regions of interest (ROIs) were investigated, based on (a) BOLD signal and (b) BOLD responses within grey matter only. M values from the latter ROI were in closer agreement with theoretical predictions; however, reassuringly, ROI choice had less impact on CMRO2 than on M estimates. Relative changes in CMRO2 during motor tasks at 3 and 7 T were in good agreement but were over-estimated at 1.5 T as a result of the lower signal to noise ratio. This result is encouraging for future studies at 7 T, but also highlights the impact of imaging and analysis choices (such as ASL sequence and ROI definition) on the calibration parameter M and on the calculation of CMRO2.


Hare, H. V., Blockley, N. P., Gardener, A. G., Clare, S., & Bulte, D. P. (2015). Investigating the field-dependence of the Davis model: Calibrated fMRI at 1.5, 3 and 7 T. NeuroImage, 112, 189-196.

Journal Article Type Article
Acceptance Date Feb 25, 2015
Online Publication Date Mar 14, 2015
Publication Date May 15, 2015
Deposit Date Dec 10, 2018
Publicly Available Date Feb 18, 2019
Journal NeuroImage
Print ISSN 1053-8119
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 112
Pages 189-196
Keywords Cognitive Neuroscience; Neurology
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Additional Information This article is maintained by: Elsevier; Article Title: Investigating the field-dependence of the Davis model: Calibrated fMRI at 1.5, 3 and 7T; Journal Title: NeuroImage; CrossRef DOI link to publisher maintained version:; Content Type: article; Copyright: Copyright © 2015 The Authors. Published by Elsevier Inc.


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