title: Fat-suppressed alternating-SSFP for whole-brain fMRI using breath-hold and visual stimulus paradigms.
abstract: OBJECTIVE
  To achieve artifact-suppressed whole-brain pass-band-balanced steady-state free precession functional MRI from a single functional magnetic resonance imaging (fMRI) scan.
  
  
  METHODS
  A complete and practical data acquisition sequence for alt-SSFP fMRI was developed. First, multishot flyback-echo-planar imaging (EPI) and echo-time shifting were used to achieve data acquisition that was robust against eddy currents, gradient delays, and ghosting artifacts. Second, a steady-state catalyzation scheme was implemented to reduce oscillations in the transient signal when catalyzing in and out of alternate steady states. Next, a short spatial-spectral radiofrequency (RF) pulse was designed to achieve excellent fat-suppression while maintaining a repetition time <15 ms to sensitize functional activation toward smaller vessels and capillaries. Lastly, parallel imaging was used to achieve whole-brain coverage and sufficiently high temporal resolution.
  
  
  RESULTS
  Breath-hold experiments showed excellent fat-suppression and alt-SSFP's capability to recover functional sensitivity from signal dropout regions of conventional gradient-echo and banding artifacts from conventional pass-band-balanced steady-state free precession. Applying fat-suppression resulted in improved activation maps and increased temporal SNR. Visual stimulus functional studies verify the proposed method's excellent functional sensitivity to neuronal activation.
  
  
  CONCLUSIONS
  Artifact-suppressed images are demonstrated, showing a practical pass-band-balanced steady-state free precession fMRI method that permits whole-brain imaging with excellent blood oxygen level-dependent sensitivity and fat suppression.
authors.affiliation: Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA.
authors.forename: Tiffany
authors.initials: T
authors.lastname: Jou
authors.affiliation: Biomedical Translational Imaging Centre, Halifax, Nova Scotia, Canada.
authors.forename: Steve
authors.initials: S
authors.lastname: Patterson
authors.affiliation: Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA.
authors.forename: John M
authors.initials: JM
authors.lastname: Pauly
authors.affiliation: Department of Radiology, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Chris V
authors.initials: CV
authors.lastname: Bowen
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging*; D016477:Artifacts; D001921:Brain / Q000000981:diagnostic imaging*; D062485:Breath Holding; D002138:Calibration; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging; D008297:Male; D009474:Neurons / Q000378:metabolism; D009991:Oscillometry; D010100:Oxygen / Q000737:chemistry; D010775:Photic Stimulation; D011846:Radio Waves; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D059629:Signal-To-Noise Ratio; D014785:Vision, Ocular
chemical_list: D010100:Oxygen
keywords: alternating-steady-state free precession; balanced steady-state free precession; blood oxygen level-dependent; fat-suppression; functional magnetic resonance imaging; whole-brain