title: Optimal echo time for functional MRI of the infant brain identified in response to noxious stimulation.
abstract: 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.
  
  
  
  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.
  
  
  
  The maximal change in BOLD occurred at a TE of 52 ms, and the average T2* across the whole brain was 99 ms.
  
  
  
  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.
authors.affiliation: Department of Paediatrics, University of Oxford, Oxford, United Kingdom.
authors.forename: Sezgi
authors.initials: S
authors.lastname: Goksan
authors.affiliation: Department of Paediatrics, University of Oxford, Oxford, United Kingdom.
authors.forename: Caroline
authors.initials: C
authors.lastname: Hartley
authors.affiliation: Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Hurley
authors.affiliation: Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.
authors.forename: Anderson M
authors.initials: AM
authors.lastname: Winkler
authors.affiliation: Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.
authors.forename: Eugene P
authors.initials: EP
authors.lastname: Duff
authors.affiliation: Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.
authors.forename: Mark
authors.initials: M
authors.lastname: Jenkinson
authors.affiliation: Nuffield Department of Anaesthetics, University of Oxford, Oxford, United Kingdom.
authors.forename: Richard
authors.initials: R
authors.lastname: Rogers
authors.affiliation: Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.
authors.forename: Stuart
authors.initials: S
authors.lastname: Clare
authors.affiliation: Department of Paediatrics, University of Oxford, Oxford, United Kingdom.
authors.forename: Rebeccah
authors.identifier: 0000-0003-1595-4846
authors.initials: R
authors.lastname: Slater
mesh_terms: D001921:Brain / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010812:Physical Stimulation
keywords: BOLD; T
   2*; brain; echo time; imaging; infants; pain