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Improving the sensitivity of spin‐echo fMRI at 3T by highly accelerated acquisitions
Author(s) -
Barghoorn Antonia,
Riemenschneider Bruno,
Hennig Jürgen,
LeVan Pierre
Publication year - 2021
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.28715
Subject(s) - resting state fmri , echo time , nuclear magnetic resonance , spin echo , functional magnetic resonance imaging , pulse sequence , sensitivity (control systems) , multislice , gradient echo , pulse (music) , magnetic resonance imaging , blood oxygenation , physics , neuroscience , medicine , optics , psychology , electronic engineering , detector , engineering , radiology
Purpose Spin‐echo (SE) functional MRI (fMRI) can be highly advantageous compared to gradient‐echo (GE) fMRI with respect to magnetic field‐inhomogeneity artifacts. However, at 3T, the majority of blood oxygenation level‐dependent (BOLD) fMRI experiments are performed using T 2 ∗ ‐weighted GE sequences because of their superior sensitivity compared to SE‐fMRI. The presented SE implementation of a highly accelerated GE pulse sequence therefore aims to improve the sensitivity of SE‐fMRI while profiting from a reduction of susceptibility‐induced signal dropout. Methods Spin‐echo MR encephalography (SE‐MREG) is compared with the more conventionally used spin‐echo echo‐planar imaging (SE‐EPI) and spin‐echo simultaneous multislice (SE‐SMS) at 3T in terms of capability to detect neuronal activations and resting‐state functional connectivity. For activation analysis, healthy subjects underwent consecutive SE‐MREG (pulse repetition time [TR] = 0.25 seconds), SE‐SMS (TR = 1.3 seconds), and SE‐EPI (TR = 4.4 seconds) scans in pseudorandomized order applied to a visual block design paradigm for generation of t ‐statistics maps. For the investigation of functional connectivity, additional resting‐state data were acquired for 5 minutes and a seed‐based correlation analysis using Stanford’s FIND (Functional Imaging in Neuropsychiatric Disorders) atlas was performed. Results The increased sampling rate of SE‐MREG relative to SE‐SMS and SE‐EPI improves the sensitivity to detect BOLD activation by 33% and 54%, respectively, and increases the capability to extract resting‐state networks. Compared with a brain region that is not affected by magnetic field inhomogeneities, SE‐MREG shows 2.5 times higher relative signal strength than GE‐MREG in mesial temporal structures. Conclusion SE‐MREG offers a viable possibility for whole‐brain fMRI with consideration of brain regions that are affected by strong susceptibility‐induced magnetic field gradients.