The effects of multi-echo fMRI combination and rapid T2*-mapping on offline and real-time BOLD sensitivity
Stephan Heunis,
Marcel Breeuwer,
César Caballero-Gaudes,
Lydia Hellrung,
Willem Huijbers,
Jacobus FA Jansen,
Rolf Lamerichs,
Svitlana Zinger,
Albert P Aldenkamp
Affiliations
Stephan Heunis
Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands; Department of Research and Development, Epilepsy Centre Kempenhaeghe, Heeze, the Netherlands; Institute of Neuroscience and Medicine, Brain & Behaviour (INM-7), Research Center Jülich, Germany; Department of Psychology, Education and Child studies, Erasmus School of Social and Behavioral Sciences, Erasmus University Rotterdam, the Netherlands; Corresponding author.
Marcel Breeuwer
Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands; Philips Healthcare, Best, the Netherlands
César Caballero-Gaudes
Basque Center on Cognition, Brain and Language, San Sebastian, Spain
Lydia Hellrung
Zurich Center for Neuroeconomics, Department of Economics, University of Zurich, Switzerland
Willem Huijbers
Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands; Philips Research, Eindhoven, the Netherlands
Jacobus FA Jansen
Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands; Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands; School for Mental Health and Neuroscience, Maastricht, the Netherlands
Rolf Lamerichs
Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands; Department of Research and Development, Epilepsy Centre Kempenhaeghe, Heeze, the Netherlands; Philips Research, Eindhoven, the Netherlands
Svitlana Zinger
Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands; Department of Research and Development, Epilepsy Centre Kempenhaeghe, Heeze, the Netherlands
Albert P Aldenkamp
Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands; Department of Research and Development, Epilepsy Centre Kempenhaeghe, Heeze, the Netherlands; School for Mental Health and Neuroscience, Maastricht, the Netherlands; Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology, Ghent University Hospital, Ghent, Belgium; Department of Neurology, Maastricht University Medical Center, Maastricht, the Netherlands
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 real-time use cases: a single-echo time series (based on Echo 2), the real-time T2*-mapped time series (T2*FIT) and four combined time series (T2*-weighted, tSNR-weighted, TE-weighted, and a new combination scheme termed T2*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 T2*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 T2*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 T2*FIT time series. We recommend the use and continued exploration of T2*FIT for offline task-based and real-time region-based fMRI analysis. Supporting information includes: a data repository (https://dataverse.nl/dataverse/rt-me-fmri), an interactive web-based application to explore the data (https://rt-me-fmri.herokuapp.com/), and further materials and code for reproducibility (https://github.com/jsheunis/rt-me-fMRI).
