title: Accelerated model-based proton resonance frequency shift temperature mapping using echo-based GRAPPA reconstruction.
abstract: OBJECTIVE
  To develop an acceleration method for MR temperature estimation using model-based proton resonance frequency (PRF) shift method.
  
  
  METHODS
  Images of 16 different echo times (TE) were acquired in one RF excitation using a multi-echo gradient-recalled echo (GRE) sequence. Fully sampled k-space data were retrospectively under-sampled at a net reduction factor between two and three using the proposed under-sampling strategy. K-spaces of three different TEs were combined together to perform the proposed reconstruction method called Echo-based GRAPPA. Ex vivo goose liver cooling experiment and in vivo breast imaging experiment were performed to investigate the accuracy of Echo-based GRAPPA. Conventional GRAPPA reconstruction was implemented for comparison using the same sampling pattern.
  
  
  RESULTS
  The goose liver imaging experiment shows that the reconstruction-induced temperature RMSE of a selected region of interest (ROI) is less than 1.4 °C for Echo-based GRAPPA at a net reduction factor of 2.3. The breast imaging experiment shows that the mean temperature error of water-fat mixed ROIs is 2.3 °C at a net reduction factor of 2.7. Conventional GRAPPA shows larger temperature RMSE than Echo-based GRAPPA.
  
  
  CONCLUSIONS
  The proposed method can accelerate the MR temperature estimation using model-based PRF at a net reduction factor between two and three with a reconstruction-induced temperature error less than 3°C in water-fat mixed ROIs.
authors.affiliation: Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China; Department of Electrical Engineering, Stanford University, CA, USA.
authors.forename: Feiyu
authors.initials: F
authors.lastname: Chen
authors.affiliation: Department of Electrical Engineering, Stanford University, CA, USA.
authors.forename: Xinwei
authors.initials: X
authors.lastname: Shi
authors.affiliation: Key Laboratory of Particle and Radiation Imaging, Ministry of Education, Department of Engineering Physics, Tsinghua University, Beijing, China.
authors.forename: Shuo
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of Electrical Engineering, Stanford University, CA, USA.
authors.forename: Ethan M
authors.initials: EM
authors.lastname: Johnson
authors.affiliation: Department of Orthopedics, First Affiliated Hospital of PLA General Hospital, Beijing, China.
authors.forename: Bingyao
authors.initials: B
authors.lastname: Chen
authors.affiliation: Department of Orthopedics, First Affiliated Hospital of PLA General Hospital, Beijing, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Ren
authors.affiliation: Department of Orthopedics, First Affiliated Hospital of PLA General Hospital, Beijing, China.
authors.forename: Xing
authors.initials: X
authors.lastname: Wei
authors.affiliation: Key Laboratory of Particle and Radiation Imaging, Ministry of Education, Department of Engineering Physics, Tsinghua University, Beijing, China.
authors.forename: Shi
authors.initials: S
authors.lastname: Wang
authors.affiliation: Key Laboratory of Particle and Radiation Imaging, Ministry of Education, Department of Engineering Physics, Tsinghua University, Beijing, China. Electronic address: kuiying2012@gmail.com.
authors.forename: Kui
authors.initials: K
authors.lastname: Ying
mesh_terms: D000273:Adipose Tissue / Q000473:pathology; D000818:Animals; D001940:Breast / Q000473:pathology; D005260:Female; D005777:Geese; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008099:Liver / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008962:Models, Theoretical; D011522:Protons; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D011522:Protons; D014867:Water
keywords: Acceleration; GRAPPA; Model-based proton resonance frequency shift; Temperature mapping