Contribution of the multi-echo approach in accelerated functional magnetic resonance imaging multiband acquisition

Kovářová A, Gajdoš M, Rektor I, Mikl M.

Hum Brain Mapp. 2022 Feb 15;43(3):955-973. doi: 10.1002/hbm.25698. Epub 2021 Oct 30. PMID: 34716738; PMCID: PMC8764472.


16 May 2022

We wanted to verify the effect of combining multi-echo (ME) functional magnetic resonance imaging (fMRI) with slice acceleration in simultaneous multi-slice acquisition. The aim was to shed light on the benefits of multiple echoes for various acquisition settings, especially for levels of slice acceleration and flip angle. Whole-brain ME fMRI data were obtained from 26 healthy volunteers (using three echoes; seven runs with slice acceleration 1, 4, 6, and 8; and two different flip angles for each of the first three acceleration factors) and processed as single-echo (SE) data and ME data based on optimal combinations weighted by the contrast-to-noise ratio. Global metrics (temporal signal-to-noise ratio, signal-to-noise separation, number of active voxels, etc.) and local characteristics in regions of interest were used to evaluate SE and ME data. ME results outperformed SE results in all runs; the differences became more apparent for higher acceleration, where a significant decrease in data quality is observed. ME fMRI can improve the observed data quality metrics over SE fMRI for a wide range of accelerated fMRI acquisitions.

Keywords: BOLD; TE dependence; acquisition acceleration; multi-echo fMRI; simultaneous multi-slice imaging.

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