title: Signal fluctuations in fMRI data acquired with 2D-EPI and 3D-EPI at 7 Tesla.
abstract: Segmented three-dimensional echo planar imaging (3D-EPI) provides higher image signal-to-noise ratio (SNR) than standard single-shot two-dimensional echo planar imaging (2D-EPI), but is more sensitive to physiological noise. The aim of this study was to compare physiological noise removal efficiency in single-shot 2D-EPI and segmented 3D-EPI acquired at 7 Tesla. Two approaches were investigated based either on physiological regressors (PR) derived from cardiac and respiratory phases, or on principal component analysis (PCA) using additional resting-state data. Results show that, prior to physiological noise removal, 2D-EPI data had higher temporal SNR (tSNR), while spatial SNR was higher in 3D-EPI. Blood oxygen level dependent (BOLD) sensitivity was similar for both methods. The PR-based approach allowed characterization of relative contributions from different noise sources, confirming significant increases in physiological noise from 2D to 3D prior to correction. Both physiological noise removal approaches produced significant increases in tSNR and BOLD sensitivity, and these increases were larger for 3D-EPI, resulting in higher BOLD sensitivity in the 3D-EPI than in the 2D-EPI data. The PCA-based approach was the most effective correction method, yielding higher tSNR values for 3D-EPI than for 2D-EPI postcorrection.
authors.affiliation: Department of Bioengineering, Instituto Superior Técnico, Technical University of Lisbon, Lisbon, Portugal.
authors.forename: João
authors.initials: J
authors.lastname: Jorge
authors.forename: Patrícia
authors.initials: P
authors.lastname: Figueiredo
authors.forename: Wietske
authors.initials: W
authors.lastname: van der Zwaag
authors.forename: José P
authors.initials: JP
authors.lastname: Marques
mesh_terms: D000328:Adult; D000465:Algorithms; D001921:Brain / Q000473:pathology; D001931:Brain Mapping / Q000379:methods; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015233:Models, Statistical; D010100:Oxygen / Q000378:metabolism; D025341:Principal Component Analysis; D015203:Reproducibility of Results; D059629:Signal-To-Noise Ratio; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D010100:Oxygen