title: Dependence of amygdala activation on echo time: results from olfactory fMRI experiments.
abstract: Echo time dependence of the BOLD sensitivity is an important topic in fMRI whenever brain regions are considered where the EPI data quality suffers from susceptibility gradients. Here, an fMRI study is presented showing that a reduced echo time EPI sequence significantly enhances the statistical inference in subcortical (limbic) brain regions, with special focus on the amygdala. As a consequence, to facilitate whole-brain fMRI with optimal echo times, a sequence with slice-dependent echo time is demonstrated with a focus on structures suffering from susceptibility changes. The applicability of this method is shown in a second fMRI study aimed at both, cortical, and limbic brain regions. The results are in good agreement with theoretical descriptions of the BOLD sensitivity under the influence of susceptibility gradients.
authors.affiliation: Institut für Medizin, Forschungszentrum Jülich, 52425 Jülich, Germany.
authors.forename: Tony
authors.initials: T
authors.lastname: Stöcker
authors.forename: Thilo
authors.initials: T
authors.lastname: Kellermann
authors.forename: Frank
authors.initials: F
authors.lastname: Schneider
authors.forename: Ute
authors.initials: U
authors.lastname: Habel
authors.forename: Katrin
authors.initials: K
authors.lastname: Amunts
authors.forename: Peter
authors.initials: P
authors.lastname: Pieperhoff
authors.forename: Karl
authors.initials: K
authors.lastname: Zilles
authors.forename: N Jon
authors.initials: NJ
authors.lastname: Shah
mesh_terms: D000328:Adult; D000679:Amygdala / Q000502:physiology*; D016477:Artifacts; D001921:Brain / Q000502:physiology; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology; D017352:Echo-Planar Imaging; D004644:Emotions / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008432:Mathematical Computing; D008570:Memory, Short-Term / Q000502:physiology; D015233:Models, Statistical; D010100:Oxygen / Q000097:blood; D012016:Reference Values; D012680:Sensitivity and Specificity; D012903:Smell / Q000502:physiology*; D013997:Time Factors
chemical_list: D010100:Oxygen