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The impact of geometric distortions and their correction on fMRI data analyses
Rodolfo Abreu1, Miguel Castelo-Branco1,2, and João Valente Duarte1,2
1Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Coimbra, Portugal, 2Faculty of Medicine, University of Coimbra, Coimbra, Portugal
Correction of geometric distortions on fMRI data from phase-reversed images or field map images improves the quality of different fMRI data analyses, with the latter yielding the best results at the cost of longer scanning times.
Fig. 1: Schematic diagram of the processing pipeline. The fMRI data of each functional run is first submitted to motion and slice timing correction. Then, geometric distortions are corrected using AP-PA or FM approaches. Subsequently, additional pre-processing steps are performed on the corrected and uncorrected data, followed by the three different data analyses: 1) registration into structural data, 2) identification of resting-state networks, and 3) mapping of task-related brain regions of interest.
Fig. 3: Ten group RSNs identified on (left) uncorrected, (middle) AP-PA corrected, and (right) FM-corrected fMRI data for the first run of the biological motion perception task. The RSN templates (in red-yellow) from 8 are superimposed with the spatial independent components (in blue-light blue) selected for each RSN template, according to their Dice coefficient (also shown above each RSN).