title: Comparison of spiral imaging and SENSE-EPI at 1.5 and 3.0 T using a controlled cerebrovascular challenge.
abstract: OBJECTIVE
  To quantitatively compare spiral imaging and sensitivity-encoded-echo-planar-imaging (SENSE-EPI) methods for blood oxygen level-dependent (BOLD) imaging using controlled changes in the end-tidal partial pressure of CO(2) (PetCO(2)) to provide a global BOLD response. Specifically, we examined susceptibility-field-gradient effects on the BOLD sensitivity throughout the brain.
  
  
  METHODS
  We quantified cerebrovascular reactivity (CVR) using the BOLD response to cyclic changes in PetCO(2) in five healthy volunteers at 1.5 and 3.0 T using spiral imaging and SENSE-EPI. We compared the two techniques with respect to susceptibility-induced signal dropout and CVR t-statistic.
  
  
  RESULTS
  Compared to spiral imaging, SENSE-EPI significantly reduced the volume of signal dropout by 32 +/- 18% at 3.0 T. In regions with large susceptibility gradients, SENSE-EPI demonstrated a trend for a greater t-statistic than spiral imaging, particularly at 3.0 T. However, no statistically significant between-technique differences existed.
  
  
  CONCLUSIONS
  The results at 3.0 T suggest that, compared with spiral imaging, SENSE-EPI reduces signal loss associated with susceptibility field gradients in affected regions without affecting BOLD sensitivity. This study also demonstrates a unique application of controlled PetCO(2) changes to quantitatively compare BOLD techniques, which may be useful for the design of future fMRI studies.
authors.affiliation: Department of Physiology and Experimental Medicine, Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Jeff D
authors.initials: JD
authors.lastname: Winter
authors.forename: Julien
authors.initials: J
authors.lastname: Poublanc
authors.forename: Adrian P
authors.initials: AP
authors.lastname: Crawley
authors.forename: Andrea
authors.initials: A
authors.lastname: Kassner
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology*; D001921:Brain / Q000033:anatomy & histology* / Q000098:blood supply / Q000502:physiology*; D002245:Carbon Dioxide; D002560:Cerebrovascular Circulation / Q000502:physiology*; D017352:Echo-Planar Imaging / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008297:Male
chemical_list: D002245:Carbon Dioxide