title: Chemical Exchange Saturation Transfer (CEST) MR Technique for Liver Imaging at 3.0 Tesla: an Evaluation of Different Offset Number and an After-Meal and Over-Night-Fast Comparison.
abstract: OBJECTIVE
  This study seeks to explore whether chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) can detect liver composition changes between after-meal and over-night-fast statuses.
  
  
  METHODS
  Fifteen healthy volunteers were scanned on a 3.0-T human MRI scanner in the evening 1.5-2 h after dinner and in the morning after over-night (12-h) fasting. Among them, seven volunteers were scanned twice to assess the scan-rescan reproducibility. Images were acquired at offsets (n = 41, increment = 0.25 ppm) from -5 to 5 ppm using a turbo spin echo (TSE) sequence with a continuous rectangular saturation pulse. Amide proton transfer-weighted (APTw) and GlycoCEST signals were quantified with the asymmetric magnetization transfer ratio (MTRasym) at 3.5 ppm and the total MTRasym integrated from 0.5 to 1.5 ppm from the corrected Z-spectrum, respectively. To explore scan time reduction, CEST images were reconstructed using 31 offsets (with 20% time reduction) and 21 offsets (with 40% time reduction), respectively.
  
  
  RESULTS
  For reproducibility, GlycoCEST measurements in 41 offsets showed the smallest scan-rescan mean measurements variability, indicated by the lowest mean difference of -0.049% (95% limits of agreement, -0.209 to 0.111%); for APTw, the smallest mean difference was found to be 0.112% (95% limits of agreement, -0.698 to 0.921%) in 41 offsets. Compared with after-meal, both GlycoCEST measurement and APTw measurement under different offset number decreased after 12-h fasting. However, as the offsets number decreased (41 offsets vs. 31 offsets vs. 21 offsets), GlycoCEST map and APTw map became more heterogeneous and noisier.
  
  
  CONCLUSIONS
  Our results show that CEST liver imaging at 3.0 T has high sensitivity for fasting.
authors.affiliation: Department of Imaging and Interventional Radiology, Faculty of Medicine, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR.
authors.forename: Min
authors.initials: M
authors.lastname: Deng
authors.affiliation: Department of Imaging and Interventional Radiology, Faculty of Medicine, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR.
authors.forename: Shu-Zhong
authors.initials: SZ
authors.lastname: Chen
authors.affiliation: Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Happy Valley, Hong Kong SAR.
authors.forename: Jing
authors.initials: J
authors.lastname: Yuan
authors.affiliation: MR Clinical Science, Philips Healthcare Greater China, Shanghai, China.
authors.forename: Queenie
authors.initials: Q
authors.lastname: Chan
authors.affiliation: Department of Radiology, Johns Hopkins University, Baltimore, MD, USA.|F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA.
authors.forename: Jinyuan
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Department of Imaging and Interventional Radiology, Faculty of Medicine, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR. yixiang_wang@cuhk.edu.hk.
authors.forename: Yì-Xiáng J
authors.initials: YX
authors.lastname: Wáng
mesh_terms: D000328:Adult; D005215:Fasting; D005260:Female; D006801:Humans; D008099:Liver / Q000737:chemistry / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D062407:Meals; D008875:Middle Aged; D015203:Reproducibility of Results
keywords: Amide proton transfer (APT); Chemical exchange saturation transfer (CEST); Glycogen; Liver; Magnetic resonance imaging