title: Post-stenotic plug-like jet with a vortex ring demonstrated by 4D flow MRI.
abstract: OBJECTIVE
  To investigate the details of the flow structure of a plug-like jet that had a vortex ring in pulsatile stenotic phantoms using 4D flow MRI.
  
  
  METHODS
  Pulsatile Newtonian flows in two stenotic phantoms with 50% and 75% reductions in area were scanned by 4D flow MRI. Blood analog working fluid was circulated via the stenotic phantom using a pulsatile pump at a constant pulsating frequency of 1Hz. The velocity and vorticity fields of the plug-like jet with a vortex ring were quantitatively analyzed in the spatial and temporal domains.
  
  
  RESULTS
  Pulsatile stenotic flow showed a plug-like jet at the specific stenotic degree of 50% in our pulsatile waveform design. This plug-like jet was found at the decelerating period in the post-stenotic region of 26.4mm (1.2 D). It revealed a vortex ring structure with vorticity strength in the range of ±100s(-1).
  
  
  CONCLUSIONS
  We observed a plug-like jet with a vortex ring in pulsatile stenotic flow by in vitro visualization using 4D flow MRI. In this plug-like jet, the local fastest flow region occurred at the post-systole phase in the post-stenotic region, which was distinguishable from a typical stenotic jet flow at systole phase.
authors.affiliation: Biomedical Engineering Research Center, Asan Institute of Life Science, Asan Medical Center, Seoul, Republic of Korea.
authors.forename: Guk Bae
authors.initials: GB
authors.lastname: Kim
authors.affiliation: POSTECH Biotech Center, Pohang University of Science and Technology, Pohang, Republic of Korea.
authors.forename: Hojin
authors.initials: H
authors.lastname: Ha
authors.affiliation: Biomedical Engineering Research Center, Asan Institute of Life Science, Asan Medical Center, Seoul, Republic of Korea.
authors.forename: Jihoon
authors.initials: J
authors.lastname: Kweon
authors.affiliation: Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, Republic of Korea.
authors.forename: Sang Joon
authors.initials: SJ
authors.lastname: Lee
authors.affiliation: Department of Cardiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea.
authors.forename: Young-Hak
authors.initials: YH
authors.lastname: Kim
authors.affiliation: Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea. Electronic address: donghyun.yang@gmail.com.
authors.forename: Dong Hyun
authors.initials: DH
authors.lastname: Yang
authors.affiliation: Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea; Department of Convergence Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea. Electronic address: namkugkim@gmail.com.
authors.forename: Namkug
authors.initials: N
authors.lastname: Kim
mesh_terms: D003251:Constriction, Pathologic; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D011673:Pulsatile Flow; D063177:Pulse Wave Analysis; D013599:Systole
keywords: 4D flow MRI; Plug-like jet; Pulsatile stenotic flow; Vortex ring