The effects of multi-echo fMRI combination and rapid T-2*-mapping on offline and real-time BOLD sensitivity

S. Heunis*, M. Breeuwer, C. Caballero-Gaudes, L. Hellrung, W. Huijbers, J.F. Jansen, R. Lamerichs, S. Zinger, A.P. Aldenkamp

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


A variety of strategies are used to combine multi-echo functional magnetic resonance imaging (fMRI) data, yet recent literature lacks a systematic comparison of the available options. Here we compare six different approaches derived from multi-echo data and evaluate their influences on BOLD sensitivity for offline and in particular realtime use cases: a single-echo time series (based on Echo 2), the real-time T 2 *-mapped time series ( T 2 * FIT ) and four combined time series ( T 2 *-weighted, tSNR-weighted, TE-weighted, and a new combination scheme termed T 2 * FIT-weighted). We compare the influences of these six multi-echo derived time series on BOLD sensitivity using a healthy participant dataset ( N = 28) with four task-based fMRI runs and two resting state runs. We show that the T 2 * FIT-weighted combination yields the largest increase in temporal signal-to-noise ratio across task and resting state runs. We demonstrate additionally for all tasks that the T 2 * FIT time series consistently yields the largest offline effect size measures and real-time region-of-interest based functional contrasts and temporal contrast-to noise ratios. These improvements show the promising utility of multi-echo fMRI for studies employing real-time paradigms, while further work is advised to mitigate the decreased tSNR of the T 2 * FIT time series. We recommend the use and continued exploration of T 2 * FIT for offline task-based and real-time region-based fMRI analysis. Supporting information includes: a data repository ( ), an interactive web-based application to explore the data ( ), and further materials and code for reproducibility ( me-fMRI ).
Original languageEnglish
Article number118244
Number of pages16
Publication statusPublished - 1 Sept 2021


  • Real-time
  • Multi-echo
  • Functional magnetic resonance imaging
  • Neurofeedback
  • Adaptive paradigms
  • Methods development
  • Finger tapping
  • Motor
  • Emotion processing
  • Amygdala
  • Task
  • Resting state
  • EPI

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