Multi-band SWIFT enables quiet and artefact-free EEG-fMRI and awake fMRI studies in rat
Jaakko Paasonen,
Hanne Laakso,
Tiina Pirttimäki,
Petteri Stenroos,
Raimo A. Salo,
Ekaterina Zhurakovskaya,
Lauri J. Lehto,
Heikki Tanila,
Michael Garwood,
Shalom Michaeli,
Djaudat Idiyatullin,
Silvia Mangia,
Olli Gröhn
Affiliations
Jaakko Paasonen
A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
Hanne Laakso
A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland; Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA
Tiina Pirttimäki
A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland; Department of Psychology, University of Jyväskyla, Jyväskyla, Finland
Petteri Stenroos
A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
Raimo A. Salo
A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
Ekaterina Zhurakovskaya
A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland; Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA
Lauri J. Lehto
A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland; Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA
Heikki Tanila
A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
Michael Garwood
Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA
Shalom Michaeli
Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA
Djaudat Idiyatullin
Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA
Silvia Mangia
Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA
Olli Gröhn
A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland; Corresponding author. A.I.V. Institute for Molecular Sciences, University of Eastern Finland, P.O. Box 1627, FI-70211, Kuopio, Finland.
Functional magnetic resonance imaging (fMRI) studies in animal models provide invaluable information regarding normal and abnormal brain function, especially when combined with complementary stimulation and recording techniques. The echo planar imaging (EPI) pulse sequence is the most common choice for fMRI investigations, but it has several shortcomings. EPI is one of the loudest sequences and very prone to movement and susceptibility-induced artefacts, making it suboptimal for awake imaging. Additionally, the fast gradient-switching of EPI induces disrupting currents in simultaneous electrophysiological recordings. Therefore, we investigated whether the unique features of Multi-Band SWeep Imaging with Fourier Transformation (MB-SWIFT) overcome these issues at a high 9.4 T magnetic field, making it a potential alternative to EPI. MB-SWIFT had 32-dB and 20-dB lower peak and average sound pressure levels, respectively, than EPI with typical fMRI parameters. Body movements had little to no effect on MB-SWIFT images or functional connectivity analyses, whereas they severely affected EPI data. The minimal gradient steps of MB-SWIFT induced significantly lower currents in simultaneous electrophysiological recordings than EPI, and there were no electrode-induced distortions in MB-SWIFT images. An independent component analysis of the awake rat functional connectivity data obtained with MB-SWIFT resulted in near whole-brain level functional parcellation, and simultaneous electrophysiological and fMRI measurements in isoflurane-anesthetized rats indicated that MB-SWIFT signal is tightly linked to neuronal resting-state activity. Therefore, we conclude that the MB-SWIFT sequence is a robust preclinical brain mapping tool that can overcome many of the drawbacks of conventional EPI fMRI at high magnetic fields.
