title: Compressed sensing reconstruction improves sensitivity of variable density spiral fMRI.
abstract: OBJECTIVE
  Functional MRI (fMRI) techniques that can provide excellent blood oxygen level dependent contrast, rapid whole brain imaging, and minimal spatial distortion are in demand. This study explored whether fMRI sensitivity can be improved through the use of compressed sensing (CS) reconstruction of variable density spiral fMRI.
  
  
  METHODS
  Three different CS-reconstructed 1-shot variable density spirals were explored (corresponding to 28%, 35%, and 46% under-sampling), and compared with conventional 1-shot and 2-shot Archimedean spirals acquired using matched echo time and volume repetition time. fMRI maps were reconstructed with or without CS MRI and sensitivity was compared using identically matched voxels.
  
  
  RESULTS
  The results demonstrated that an l1 -norm based CS reconstruction only led to an increase in functional contrast when applied to 28% under-sampled data. A whole brain t-contrast map revealed that 2-shot uniformly sampled spiral and 28% under-sampled spiral data reconstructed with CS yield equivalent sensitivity, even with matched echo time and volume repetition time
  
  
  CONCLUSIONS
  VD spiral exhibits a useful operating range, in the region of 25-30% under-sampling, for which CS reconstruction can be used to increase the sensitivity of fMRI to brain activity. Using CS, VD acquisitions achieve the same sensitivity as 2-shot Archimedean acquisitions, but require only a single shot.
authors: Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK.
authors: D J
authors: DJ
authors: Holland
authors: C
authors: C
authors: Liu
authors: X
authors: X
authors: Song
authors: E L
authors: EL
authors: Mazerolle
authors: M T
authors: MT
authors: Stevens
authors: A J
authors: AJ
authors: Sederman
authors: L F
authors: LF
authors: Gladden
authors: R C N
authors: RC
authors: D'Arcy
authors: C V
authors: CV
authors: Bowen
authors: S D
authors: SD
authors: Beyea
mesh_terms: D000465:Algorithms; D001931:Brain Mapping / Q000379:methods*; D002540:Cerebral Cortex / Q000502:physiology*; D044962:Data Compression / Q000379:methods*; D005071:Evoked Potentials / Q000502:physiology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: compressed sensing; fMRI; spiral; variable-density