Advances in resting state fMRI acquisitions for functional connectomics

• Published in: NeuroImage (Orlando, Fla.) Vol. 243; p. 118503
• Main Authors: Raimondo, Luisa, Oliveira, ĺcaro A.F., Heij, Jurjen, Priovoulos, Nikos, Kundu, Prantik, Leoni, Renata Ferranti, van der Zwaag, Wietske
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.11.2021; Elsevier Limited; Elsevier
• Subjects: Blood flow; Brain - diagnostic imaging; Brain architecture; Brain mapping; Brain Mapping - methods; Cerebral blood flow; Cerebrovascular Circulation; Connectome; Echo planar imaging; Functional connectome; Functional magnetic resonance imaging; High field; Humans; Magnetic Resonance Imaging - methods; ME-EPI; Neocortex; Nerve Net - physiology; Neuroimaging; Oscillations; Oxygen Saturation - physiology; Physiology; Rest - physiology; Resting state; Scanners; Substantia alba; High field; Resting state; Functional connectome; Echo planar imaging; ME-EPI
• ISSN: 1053-8119; 1095-9572; 1095-9572
• DOI: 10.1016/j.neuroimage.2021.118503

•Most rs-fMRI is done at 3T with T2*w-EPI of moderate spatiotemporal resolution.•7T rs-fMRI offers higher spatial resolution, for example to study cortical depths.•Multiband EPI and other undersampling schemes are used to increase the sampling rate.•Multi-echo EPI allows measurement of connectivity of deep gray matter structures.•Alternative contrasts include VASO-CBV and T2-weighting (for spatial specificity).•Another alternative contrast, CBF, is often used for connectivity measures in clinical populations. Resting state functional magnetic resonance imaging (rs-fMRI) is based on spontaneous fluctuations in the blood oxygen level dependent (BOLD) signal, which occur simultaneously in different brain regions, without the subject performing an explicit task. The low-frequency oscillations of the rs-fMRI signal demonstrate an intrinsic spatiotemporal organization in the brain (brain networks) that may relate to the underlying neural activity. In this review article, we briefly describe the current acquisition techniques for rs-fMRI data, from the most common approaches for resting state acquisition strategies, to more recent investigations with dedicated hardware and ultra-high fields. Specific sequences that allow very fast acquisitions, or multiple echoes, are discussed next. We then consider how acquisition methods weighted towards specific parts of the BOLD signal, like the Cerebral Blood Flow (CBF) or Volume (CBV), can provide more spatially specific network information. These approaches are being developed alongside the commonly used BOLD-weighted acquisitions. Finally, specific applications of rs-fMRI to challenging regions such as the laminae in the neocortex, and the networks within the large areas of subcortical white matter regions are discussed. We finish the review with recommendations for acquisition strategies for a range of typical applications of resting state fMRI.