title: Combined parallel and partial fourier MR reconstruction for accelerated 8-channel hyperpolarized carbon-13 in vivo magnetic resonance Spectroscopic imaging (MRSI).
abstract: OBJECTIVE
  To implement and evaluate combined parallel magnetic resonance imaging (MRI) and partial Fourier acquisition and reconstruction for rapid hyperpolarized carbon-13 ((13) C) spectroscopic imaging. Short acquisition times mitigate hyperpolarized signal losses that occur due to T1 decay, metabolism, and radiofrequency (RF) saturation. Human applications additionally require rapid imaging to permit breath-holding and to minimize the effects of physiologic motion.
  
  
  METHODS
  Numerical simulations were employed to validate and characterize the reconstruction. In vivo MR spectroscopic images were obtained from a rat following injection of hyperpolarized (13) C pyruvate using an 8-channel array of carbon-tuned receive elements.
  
  
  RESULTS
  For small spectroscopic matrix sizes, combined parallel imaging and partial Fourier undersampling resulted primarily in decreased spatial resolution, with relatively less visible spatial aliasing. Parallel reconstruction qualitatively restored lost image detail, although some pixel spectra had persistent numerical error. With this technique, a 30 × 10 × 16 matrix of 4800 3D MR spectroscopy imaging voxels from a whole rat with isotropic 8 mm(3) resolution was acquired within 11 seconds.
  
  
  CONCLUSIONS
  Parallel MRI and partial Fourier acquisitions can provide the shorter imaging times and wider spatial coverage that will be necessary as hyperpolarized (13) C techniques move toward human clinical applications.
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA 94143, USA. Michael.ohliger@ucsf.edu
authors.forename: Michael A
authors.initials: MA
authors.lastname: Ohliger
authors.forename: Peder E Z
authors.initials: PE
authors.lastname: Larson
authors.forename: Robert A
authors.initials: RA
authors.lastname: Bok
authors.forename: Peter
authors.initials: P
authors.lastname: Shin
authors.forename: Simon
authors.initials: S
authors.lastname: Hu
authors.forename: James
authors.initials: J
authors.lastname: Tropp
authors.forename: Fraser
authors.initials: F
authors.lastname: Robb
authors.forename: Lucas
authors.initials: L
authors.lastname: Carvajal
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Nelson
authors.forename: John
authors.initials: J
authors.lastname: Kurhanewicz
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Vigneron
mesh_terms: D000465:Algorithms; D000818:Animals; D002244:Carbon / Q000378:metabolism*; D002247:Carbon Isotopes / Q000493:pharmacokinetics*; D005583:Fourier Analysis; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D057054:Molecular Imaging / Q000379:methods*; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D002247:Carbon Isotopes; D002244:Carbon
keywords: carbon-13; hyperpolarized; parallel imaging; spectroscopy