title: Stimulated echo diffusion weighted imaging of the liver at 3 Tesla.
abstract: Diffusion time (Δ) effect in diffusion measurements has been validated as a sensitive biomarker in liver fibrosis by rat models. To extend this finding to clinical study, a reliable imaging technique is highly desirable. This study aimed to develop an optimal stimulated echo acquisition mode (STEAM) diffusion-weighted imaging (DWI) method dedicated to human liver imaging on 3 Tesla (T) and preliminarily investigate the dependence effect in healthy volunteers.
  
  
  
  STEAM DWI with single-shot echo planar imaging readout was used as it provided better signal-to-noise ratio (SNR) than spin echo DWI methods when a long Δ was needed for liver imaging. Additionally, a slice-selection gradient reversal method was used for fat suppression. Motion compensation and SNR improvement strategies were used to further improve the image quality. Five b-values with three Δs were tested in 10 volunteers.
  
  
  
  Effective fat suppression and motion compensation were reproducibly achieved in the optimized sequence. The signal decay generally became slower when the Δs increased. Obvious reduction of diffusion coefficients was observed with increasing Δs in the liver.
  
  
  
  The results verified the Δ dependence in diffusion measurements, indicating restricted diffusion in healthy human livers for the first time at 3T. This prepared STEAM DWI a potential technique for liver fibrotic studies in clinical practice. Magn Reson Med 77:300-309, 2017. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, Beijing, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, Beijing, China.
authors.forename: Aiqi
authors.initials: A
authors.lastname: Sun
authors.affiliation: Department of Medical Imaging Center, Beijing You An Hospital, Capital Medical University, Beijing, China.
authors.forename: Hongjun
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Radiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Pairash
authors.initials: P
authors.lastname: Saiviroonporn
authors.affiliation: Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong SAR, China.|Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Ed X
authors.initials: EX
authors.lastname: Wu
authors.affiliation: Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, Beijing, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Guo
mesh_terms: D062485:Breath Holding; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008099:Liver / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results
keywords: STEAM DWI; diffusion time dependence; liver DWI; restricted diffusion