title: Spiral-in/out BOLD fMRI for increased SNR and reduced susceptibility artifacts.
abstract: BOLD fMRI is hampered by dropout of signal in the orbitofrontal and parietal brain regions due to magnetic field gradients near air-tissue interfaces. This work reports the use of spiral-in trajectories that begin at the edge of k-space and end at the origin, and spiral in/out trajectories in which a spiral-in readout is followed by a conventional spiral-out trajectory. The spiral-in trajectory reduces the dropout and increases the BOLD contrast. The spiral-in and spiral-out images can be combined in several ways to simultaneously achieve increased signal-to-noise ratio (SNR) and reduced dropout artifacts. Activation experiments employing an olfaction task demonstrate significantly increased activation volumes due to reduced dropout, and overall increased SNR in all regions.
authors.affiliation: Department of Radiology, Center for Advanced MR Technology, Stanford University School of Medicine, Stanford, California 94305-5488, USA. gary@s-world.stanford.edu
authors.forename: G H
authors.initials: GH
authors.lastname: Glover
authors.forename: C S
authors.initials: CS
authors.lastname: Law
mesh_terms: D000679:Amygdala / Q000033:anatomy & histology / Q000502:physiology*; D016477:Artifacts; D001931:Brain Mapping; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D009833:Olfactory Pathways / Q000033:anatomy & histology / Q000502:physiology*; D012016:Reference Values; D012903:Smell / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology