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. 2017 Aug;78(2):625-631.
doi: 10.1002/mrm.26455. Epub 2016 Sep 21.

Optimal echo time for functional MRI of the infant brain identified in response to noxious stimulation

Sezgi Goksan  1 , Caroline Hartley  1 , Samuel A Hurley  2 , Anderson M Winkler  2 , Eugene P Duff  2 , Mark Jenkinson  2 , Richard Rogers  3 , Stuart Clare  2 , Rebeccah Slater  1
Affiliations

Optimal echo time for functional MRI of the infant brain identified in response to noxious stimulation

Sezgi Goksan et al. Magn Reson Med. 2017 Aug.

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.

Keywords: BOLD; T  2*; brain; echo time; imaging; infants; pain.

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Figures

Figure 1
Figure 1
Calculation of the optimal TE across the whole brain. (a) Mean percentage change in BOLD was calculated from EPI data collected at five different echo times (n = 23, TE range: 30–70 ms). The mean (crosses) and standard error of the mean are indicated at each TE. A second‐order polynomial was fitted to the data (black line). An asterisk (red) identifies the TE at which the fitted curve is maximal (TE = 52 ms). The circles (light blue) represent the mean percentage change in BOLD in individual infants. (b) Histogram of the optimal TE calculated for each voxel (range: 30–70 ms). The average optimal TE = 52 ms. BOLD, blood oxygen level dependent; EPI, echo planar imaging; TE, echo time.
Figure 2
Figure 2
Optimal TE investigated within four ROIs. The mean percentage change in BOLD at different TEs are reported in the bilateral (a) ACC, (b) insula, (c) postcentral gyrus, and (d) thalamus. The mean (crosses) and standard error of the mean are indicated at each TE. A second‐order polynomial was fitted to the data (black line). In each ROI, an asterisk (red) identifies the TE at which the fitted curve is maximal. The TE that generates the maximal mean percentage changes in BOLD signal is given in Table 2. The circles (light blue) represent the mean percentage change in BOLD in individual infants. ACC, anterior cingulate cortex; BOLD, blood oxygen level dependent; EPI, echo planar imaging; ROI, region of interest; TE, echo time.
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References

    1. Menon RS, Ogawa S, Tank DW, Uǧurbil K. 4 Tesla gradient recalled echo characteristics of photic stimulation‐induced signal changes in the human primary visual cortex. Magn Reson Med 1993;30:380–386. - PubMed
    1. Bandettini PA, Wong EC, Jesmanowicz A, Hinks RS, Hyde JS. Spin‐echo and gradient‐echo EPI of human brain activation using BOLD contrast: a comparative study at 1.5 T. NMR Biomed 1994;7:12–20. - PubMed
    1. van Gelderen P, Duyn JH, Liu G, Moonen CTW. Optimal T2* weighting for BOLD‐type functional MRI of the human brain. Proc Indian Acad Sci (Chem Sci) 1994;106:1617–1624.
    1. Fera F, Yongbi MN, van Gelderen P, Frank JA, Mattay VS, Duyn JH. EPI‐BOLD fMRI of human motor cortex at 1.5 T and 3.0 T: Sensitivity dependence on echo time and acquisition bandwidth. J Magn Reson Imaging 2003;19:19–26. - PubMed
    1. Wansapura JP, Holland SK, Dunn RS, Ball WS. NMR relaxation times in the human brain at 3.0 tesla. J Magn Reson Imaging 1999;9:531–538. - PubMed

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