Optimal echo time for functional MRI of the infant brain identified in response to noxious stimulation.
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ABSTRACT: Purpose
Blood oxygen level dependent (BOLD) brain activity, measured using functional MRI (fMRI), is dependent on the echo time (TE) and the reversible spin-spin relaxation time constant ( T2*) that describes the decay of transverse magnetization. Use of the optimal TE during fMRI experiments allows maximal sensitivity to BOLD to be achieved. Reports that T2* values are longer in infants (due to higher water concentrations and lower lipid content) have led to the use of longer TEs during infant fMRI experiments; however, the optimal TE has not been established.Methods
In this study, acute experimental mildly noxious stimuli were applied to the heel in 12 term infants (mean gestational age?=?40 weeks, mean postnatal age?=?3 days); and the percentage change in BOLD activity was calculated across a range of TEs, from 30 to 70 ms, at 3 Tesla. In addition, T2* maps of the whole brain were collected in seven infants.Results
The maximal change in BOLD occurred at a TE of 52 ms, and the average T2* across the whole brain was 99 ms.Conclusion
A TE of approximately 50 ms is recommended for use in 3T fMRI investigations in term infants. Magn Reson Med 78:625-631, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.
SUBMITTER: Goksan S
PROVIDER: S-EPMC5516146 | biostudies-literature | 2017 Aug
REPOSITORIES: biostudies-literature
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