title: Turbulent Kinetic Energy Measurement Using Phase Contrast MRI for Estimating the Post-Stenotic Pressure Drop: In Vitro Validation and Clinical Application.
abstract: BACKGROUND
  Although the measurement of turbulence kinetic energy (TKE) by using magnetic resonance imaging (MRI) has been introduced as an alternative index for quantifying energy loss through the cardiac valve, experimental verification and clinical application of this parameter are still required.
  
  
  OBJECTIVE
  The goal of this study is to verify MRI measurements of TKE by using a phantom stenosis with particle image velocimetry (PIV) as the reference standard. In addition, the feasibility of measuring TKE with MRI is explored.
  
  
  METHODS
  MRI measurements of TKE through a phantom stenosis was performed by using clinical 3T MRI scanner. The MRI measurements were verified experimentally by using PIV as the reference standard. In vivo application of MRI-driven TKE was explored in seven patients with aortic valve disease and one healthy volunteer. Transvalvular gradients measured by MRI and echocardiography were compared.
  
  
  RESULTS
  MRI and PIV measurements of TKE are consistent for turbulent flow (0.666 < R2 < 0.738) with a mean difference of -11.13 J/m3 (SD = 4.34 J/m3). Results of MRI and PIV measurements differ by 2.76 ± 0.82 cm/s (velocity) and -11.13 ± 4.34 J/m3 (TKE) for turbulent flow (Re > 400). The turbulence pressure drop correlates strongly with total TKE (R2 = 0.986). However, in vivo measurements of TKE are not consistent with the transvalvular pressure gradient estimated by echocardiography.
  
  
  CONCLUSIONS
  These results suggest that TKE measurement via MRI may provide a potential benefit as an energy-loss index to characterize blood flow through the aortic valve. However, further clinical studies are necessary to reach definitive conclusions regarding this technique.
authors.affiliation: POSTECH Biotech Center, Pohang University of Science and Technology, Pohang, South Korea.
authors.forename: Hojin
authors.initials: H
authors.lastname: Ha
authors.affiliation: Asan Institute of Life Science, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.
authors.forename: Guk Bae
authors.initials: GB
authors.lastname: Kim
authors.affiliation: Department of Cardiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea.
authors.forename: Jihoon
authors.initials: J
authors.lastname: Kweon
authors.affiliation: Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, South Korea.
authors.forename: Hyung Kyu
authors.initials: HK
authors.lastname: Huh
authors.affiliation: Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, South Korea.
authors.forename: Sang Joon
authors.initials: SJ
authors.lastname: Lee
authors.affiliation: Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea.
authors.forename: Hyun Jung
authors.initials: HJ
authors.lastname: Koo
authors.affiliation: Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea.
authors.forename: Joon-Won
authors.initials: JW
authors.lastname: Kang
authors.affiliation: Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea.
authors.forename: Tae-Hwan
authors.initials: TH
authors.lastname: Lim
authors.affiliation: Department of Cardiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea.
authors.forename: Dae-Hee
authors.initials: DH
authors.lastname: Kim
authors.affiliation: Department of Cardiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South 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, South Korea.|Department of Convergence Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea.
authors.forename: Namkug
authors.initials: N
authors.lastname: Kim
authors.affiliation: Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea.
authors.forename: Dong Hyun
authors.initials: DH
authors.lastname: Yang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019412:Anatomy, Cross-Sectional; D001022:Aortic Valve Insufficiency / Q000000981:diagnostic imaging / Q000503:physiopathology; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001783:Blood Flow Velocity; D001794:Blood Pressure; D015150:Echocardiography, Doppler; D005240:Feasibility Studies; D005260:Female; D005583:Fourier Analysis; D006350:Heart Valve Prosthesis; D018056:Hemorheology; D006801:Humans; D021621:Imaging, Three-Dimensional; D007700:Kinetics; D017078:Laser-Doppler Flowmetry / Q000379:methods / Q000592:standards; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D066330:Printing, Three-Dimensional