title: Feasibility and reproducibility of echo planar spectroscopic imaging on the quantification of hepatic fat.
abstract: OBJECTIVE
  1H-MRS is widely regarded as the most accurate noninvasive method to quantify hepatic fat content (HFC). When practical period of breath holding, and acquisition of HFC over multiple liver areas is considered, a fast MR spectroscopic imaging technique is desired. The aim of this study is to examine the feasibility and reproducibility of echo planar spectroscopic imaging (EPSI) on the quantification of HFC in subject with various HFCs.
  
  
  METHODS
  Twenty two volunteers were examined in a 3T MR system. The acquisition time of proposed EPSI protocol was 18 seconds. The EPSI scans were repeated 8 times for each subject to test reproducibility. The peak of water and individual peaks of fat including methyl, methylene, and allylic peaks at 0.9, 1.3, and 2.0 ppm were fitted. Calculated amount of water and fat content were corrected for T2 relaxation. The total HFC was defined as the combination of individual peaks. Standard deviation (SD), coefficient of variance (COV) and fitting reliability of HFC quantified by LCModel were calculated.
  
  
  RESULTS
  Our results show that the SDs of total HFC for all subjects are less than 2.5%. Fitting reliability is mostly under 10% and positively correlates with COV. Subjects separated into three subgroups according to quantified total HFC show that improved fitting reliability and reproducibility can be achieved on subjects with higher total HFC.
  
  
  CONCLUSIONS
  We have demonstrated feasibility of the proposed EPSI protocols on the quantification of HFC over a whole slice of liver with scan time in a single breath hold.
authors.affiliation: Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan.
authors.forename: Yi-Ru
authors.initials: YR
authors.lastname: Lin
authors.affiliation: Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan.
authors.forename: Jian-Jia
authors.initials: JJ
authors.lastname: Chiu
authors.affiliation: Graduate Institute of Applied Physics, National Chengchi University, Taipei, Taiwan.
authors.forename: Shang-Yueh
authors.initials: SY
authors.lastname: Tsai
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology*; D000704:Analysis of Variance; D017352:Echo-Planar Imaging / Q000379:methods*; D005240:Feasibility Studies; D006801:Humans; D008099:Liver / Q000033:anatomy & histology*; D015203:Reproducibility of Results; D013997:Time Factors