Abstract #1149

Low spatial-frequency ripple artifacts in layer-fMRI EPI: Identification, cause, and mitigation strategies with Dual-polarity readout

Renzo Huber¹, Rüdiger Stirnberg², David A Feinberg^1,3,4, Samantha J Ma⁵, Philipp Ehses², Omer Faruk Gulban^1,6, Jonathan R Polimeni⁷, Kenshu Koiso^1,8, Emily Ma¹, Alexander JS Beckett^3,4, Tony Stöcker², Peter Bandettini⁹, and Benedikt A Poser¹

¹Maastricht University, Maastricht, Netherlands, ²German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany, ³Helen Wills Neuroscience Institute, University of California, Berkeley, CA, United States, ⁴Advanced MRI Technologies, Sebastopol, CA, United States, ⁵Siemens Medical Solutions USA, Inc., Berkeley, CA, United States, ⁶Brain Innovation, Maastricht, Netherlands, ⁷Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, ⁸Graduate School of Informatics and Engineering, The University of Electro-Communications, Tokyo, Japan, ⁹National institutes of HEalth, Bethesda, MD, United States

Synopsis

Keywords: Artifacts, fMRI, layer-fMRI, UHF, EPIHigh-resolution layer-fMRI has great potential to inform network-neuroscience. However, it is limited by EPI artifacts. Here, we discuss a class of fuzzy EPI ghosts arising from asymmetric trapezoidal gradients with ramp sampling. A meta analysis across layer-fMRI datasets finds this artifact everywhere, without exceptions. We believe that this artifact is constraining spatiotemporal resolutions more than SNR. In this abstract we aim to raise awareness for this artifact and evaluate mitigation strategies: dual-polarity EPI. We show that dual-polarity EPI allows layer-fMRI to break the barriers of current resolution limits: It allows 0.53mm imaging at 3T, and whole-brain 0.6mm fMRI at 7T.

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