title: Short repetition time multiband echo-planar imaging with simultaneous pulse recording allows dynamic imaging of the cardiac pulsation signal.
abstract: OBJECTIVE
  Recently developed simultaneous multislice echo-planar imaging (EPI) sequences permit imaging of the whole brain at short repetition time (TR), allowing the cardiac fluctuations to be fully sampled in blood-oxygen-level dependent functional MRI (BOLD fMRI). A novel low computational analytical method was developed to dynamically map the passage of the pulsation signal through the brain and visualize the whole cerebral vasculature affected by the pulse signal. This algorithm is based on a simple combination of fast BOLD fMRI and the scanner's own built-in pulse oximeter.
  
  
  METHODS
  Multiple, temporally shifted copies of the pulse oximeter data (with 0.08 s shifting step and coverage of a 1-s span) were downsampled and used as cardiac pulsation regressors in a general linear model based analyses (FSL) of the fMRI data. The resulting concatenated z-statistics maps show the voxels that are affected as the cardiac signal travels through the brain.
  
  
  RESULTS
  Many voxels were highly correlated with the pulsation regressor or its temporally shifted version. The dynamic and static cardiac pulsation maps obtained from both the task and resting state scans, resembled cerebral vasculature.
  
  
  CONCLUSIONS
  The results demonstrated: (i) cardiac pulsation significantly affects most voxels in the brain; (ii) combining fast fMRI and this analytical method can reveal additional clinical information to functional studies.
authors.affiliation: Brain Imaging Center, McLean Hospital, Belmont, Massachusetts, USA; Department of Psychiatry, Harvard University Medical School, Boston, Massachusetts, USA.
authors.forename: Yunjie
authors.initials: Y
authors.lastname: Tong
authors.forename: Lia M
authors.initials: LM
authors.lastname: Hocke
authors.forename: Blaise deB
authors.initials: Bd
authors.lastname: Frederick
mesh_terms: D000328:Adult; D000465:Algorithms; D001921:Brain / Q000098:blood supply*; D001931:Brain Mapping / Q000379:methods*; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D064368:Healthy Volunteers; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010092:Oximetry
keywords: BOLD fMRI; cardiac pulsation; cerebral vasculature; correlation analysis; multiband EPI