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Abstract #5463

Improved detection of neuronal-related BOLD events of unknown timing with Multi-Echo Sparse Paradigm Free Mapping

Cesar Caballero-Gaudes1, Javier Gonzalez-Castillo2, and Peter A Bandettini2,3

1Basque Center on Cognition, Brain and Language, San Sebastian, Spain, 2Section on Functional Imaging Methods, National Institute of Mental Health, Bethesda, MD, United States, 3FMRI Core, National Institute of Mental Health, Bethesda, MD, United States

This work introduces an extension of sparse paradigm free mapping (SPFM) for multiecho (ME) fMRI: ME-SPFM. Based on the ME-fMRI signal model and L1-norm regularized estimators, ME-SPFM produces voxel-wise estimates of time-varying changes in the transverse relaxation ($$$R_2^*$$$) and the net magnetization ($$$S_0$$$) without prior information about experimental paradigms. Our evaluations demonstrate that ME-SPFM significantly outperforms its SE counterpart in terms of sensitivity and specificity, nearly matching that of traditional model-based analyses. ME-SPFM’s ability to blindly detect individual events at the single-subject level makes it an ideal candidate to explore the time-varying nature of brain activity in experimentally unconstrained paradigms (naturalistic, resting-state) or clinical applications (detection of inter-ictal epileptic events).

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