High field multi-echo fMRI in infants
Poster No:
1286
Submission Type:
Abstract Submission
Authors:
Julia Moser1,2, Kimberly Weldon1, Sooyeon Sung1,2, Alireza Sadeghi-Tarakameh3, Thomas Madison1, Hannah Pham1,4, Jacob Lundquist1, Edward Auerbach3, Gregor Adriany3, Yigitcan Eryaman3, Steve Nelson1,5, Jed Elison1,2,5, Damien Fair1,2,5, Essa Yacoub3
Institutions:
1Masonic Institute for the Developing Brain, University of Minnesota, Minneapolis, MN, 2Institute of Child Development, University of Minnesota, Minneapolis, MN, 3Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, 4Department of Neuroscience, University of Minnesota, Minneapolis, MN, 5Department of Pediatrics, University of Minnesota, Minneapolis, MN
First Author:
Julia Moser
Masonic Institute for the Developing Brain, University of Minnesota|Institute of Child Development, University of Minnesota
Minneapolis, MN|Minneapolis, MN
Masonic Institute for the Developing Brain, University of Minnesota|Institute of Child Development, University of Minnesota
Minneapolis, MN|Minneapolis, MN
Co-Author(s):
Sooyeon Sung
Masonic Institute for the Developing Brain, University of Minnesota|Institute of Child Development, University of Minnesota
Minneapolis, MN|Minneapolis, MN
Masonic Institute for the Developing Brain, University of Minnesota|Institute of Child Development, University of Minnesota
Minneapolis, MN|Minneapolis, MN
Alireza Sadeghi-Tarakameh
Center for Magnetic Resonance Research, University of Minnesota
Minneapolis, MN
Center for Magnetic Resonance Research, University of Minnesota
Minneapolis, MN
Hannah Pham
Masonic Institute for the Developing Brain, University of Minnesota|Department of Neuroscience, University of Minnesota
Minneapolis, MN|Minneapolis, MN
Masonic Institute for the Developing Brain, University of Minnesota|Department of Neuroscience, University of Minnesota
Minneapolis, MN|Minneapolis, MN
Steve Nelson
Masonic Institute for the Developing Brain, University of Minnesota|Department of Pediatrics, University of Minnesota
Minneapolis, MN|Minneapolis, MN
Masonic Institute for the Developing Brain, University of Minnesota|Department of Pediatrics, University of Minnesota
Minneapolis, MN|Minneapolis, MN
Jed Elison
Masonic Institute for the Developing Brain, University of Minnesota|Institute of Child Development, University of Minnesota|Department of Pediatrics, University of Minnesota
Minneapolis, MN|Minneapolis, MN|Minneapolis, MN
Masonic Institute for the Developing Brain, University of Minnesota|Institute of Child Development, University of Minnesota|Department of Pediatrics, University of Minnesota
Minneapolis, MN|Minneapolis, MN|Minneapolis, MN
Damien Fair
Masonic Institute for the Developing Brain, University of Minnesota|Institute of Child Development, University of Minnesota|Department of Pediatrics, University of Minnesota
Minneapolis, MN|Minneapolis, MN|Minneapolis, MN
Masonic Institute for the Developing Brain, University of Minnesota|Institute of Child Development, University of Minnesota|Department of Pediatrics, University of Minnesota
Minneapolis, MN|Minneapolis, MN|Minneapolis, MN
Introduction:
Important insight into brain structure and function during early development can be gained from fMRI in infants. However, a number of methodological challenges arise when working with this age group that go beyond practical considerations. Lacking commercially available head coils optimized for developmental populations, the use of head coils designed for adults results in sub-optimal signal-to-noise ratios and increases in partial voluming because of the smaller brain sizes relative to the standard voxel sizes [1]. Higher spatial resolutions can be achieved by moving to higher field strengths (i.e. > 3T). However, despite the availability of FDA approved 7T MRI scanners, they are rarely used in infants because it requires additional safety considerations [2]. Further, the most popular 7T system, the Siemens Magnetom Terra, is currently not FDA-approved for subjects as light as infants (<30kg). Independent of field strength, finding optimal acquisition protocols, which consider the tissue properties of the developing brain, is an additional challenge. We recently showed that multi-echo (ME) fMRI at 3T could be a promising tool to account for this in a developmental population [3]. Up to now, the application of ME fMRI sequences have not been tested in infants at 7T. We show initial results from a high resolution 7T ME-fMRI acquisition and compare them to an adult as a reference.
Methods:
The example infant presented here was a healthy full-term infant, seven weeks old from whom we acquired 3T and 7T data within a four day period. To make 7T acquisition possible, we developed an in-house system to assess the safe operating power limits for a newborn infant. Functional data at 3T was acquired using a four-echo sequence (14ms, 39ms, 64ms, 88ms, TR = 1.761s, 2mm res). Functional data at 7T was acquired using a three-echo sequence (14ms, 35ms, 57ms, TR = 1.768s, 1.6mm res). T2w and T1w anatomical references were acquired at 3T. All data acquisitions were performed during natural sleep. We preprocessed data using NORDIC [4] for thermal denoising, BIBSnet [5] for creating segmentations of the anatomical data, Nibabies [6] with its multi-echo preprocessing workflow and XCP-D [7] for functional connectivity processing. Functional connectivity matrices were calculated using low motion data (framewise displacement < 0.3mm) only.
Results:
All ME data acquired at 3T and 7T showed high functional tissue contrast, indicating that despite halving the voxel volume at 7T, sensitivity was still not limited (Figure 1). As expected, T2* relaxation times for the same infant across both field strengths were shorter in 7T compared to 3T, to a similar extent than in the adult (Figure 2A). At both field strengths, T2* across the cortex revealed a similar variance and showed similar areas with shorter T2*s due to susceptibility artifacts, highlighting the benefits of ME imaging. Functional connectivity matrices showed similar correlation patterns between brain regions for data acquired at 3T and 7T. However, the absolute magnitude of functional connections was higher in data acquired at 7T (Figure 2B).
·Figure 1: Multi-echo fMRI data of same infant acquired at 3T and 7T.
·Figure 2: A) T2* relaxation times. Histograms show distribution across the surface. B) Example functional connectivity seedmap showing increase in magnitude of functional connections.
Conclusions:
Our initial results show that ME fMRI in infants at 7T is not only feasible but feasible with much higher resolutions, resulting in data with high specificity and sensitivity. Investigation of T2* relaxation times points towards similar advantages of ME fMRI in infants in 7T as previously shown in 3T [3]. The observed increase in functional connectivity strength is consistent with the adult literature [8] and our example adult subject. Given careful safety considerations and suitable acquisition protocols, 7T imaging could be established as a promising tool for developmental neuroimaging as the smaller voxel size achievable at 7T is more suitable for the size of an infant brain. Moving forward, further benefits for functional connectivity research that go beyond the absolute strength of connections can be explored as well as even smaller voxel sizes.
Lifespan Development:
Early life, Adolescence, Aging
Normal Brain Development: Fetus to Adolescence 1
Modeling and Analysis Methods:
fMRI Connectivity and Network Modeling
Methods Development
Novel Imaging Acquisition Methods:
BOLD fMRI 2
Keywords:
Development
FUNCTIONAL MRI
HIGH FIELD MR
PEDIATRIC
1|2Indicates the priority used for review
Provide references using author date format
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