title: Altered Right Ventricular Kinetic Energy Work Density and Viscous Energy Dissipation in Patients with Pulmonary Arterial Hypertension: A Pilot Study Using 4D Flow MRI.
abstract: BACKGROUND
  Right ventricular (RV) function has increasingly being recognized as an important predictor for morbidity and mortality in patients with pulmonary arterial hypertension (PAH). The increased RV after-load increase RV work in PAH. We used time-resolved 3D phase contrast MRI (4D flow MRI) to derive RV kinetic energy (KE) work density and energy loss in the pulmonary artery (PA) to better characterize RV work in PAH patients.
  
  
  METHODS
  4D flow and standard cardiac cine images were obtained in ten functional class I/II patients with PAH and nine healthy subjects. For each individual, we calculated the RV KE work density and the amount of viscous dissipation in the PA.
  
  
  RESULTS
  PAH patients had alterations in flow patterns in both the RV and the PA compared to healthy subjects. PAH subjects had significantly higher RV KE work density than healthy subjects (94.7±33.7 mJ/mL vs. 61.7±14.8 mJ/mL, p = 0.007) as well as a much greater percent PA energy loss (21.1±6.4% vs. 2.2±1.3%, p = 0.0001) throughout the cardiac cycle. RV KE work density and percent PA energy loss had mild and moderate correlations with RV ejection fraction.
  
  
  CONCLUSIONS
  This study has quantified two kinetic energy metrics to assess RV function using 4D flow. RV KE work density and PA viscous energy loss not only distinguished healthy subjects from patients, but also provided distinction amongst PAH patients. These metrics hold promise as imaging markers for RV function.
authors.affiliation: Cardiovascular Division, University of Pennsylvania, Philadelphia, PA, United States of America.
authors.forename: Q Joyce
authors.initials: QJ
authors.lastname: Han
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States of America.
authors.forename: Walter R T
authors.initials: WR
authors.lastname: Witschey
authors.affiliation: Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, United States of America.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Fang-Yen
authors.affiliation: Cardiovascular Division, Temple University, Philadelphia, PA, United States of America.
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Arkles
authors.affiliation: Department of Radiology, Northwestern University, Chicago, IL, United States of America.
authors.forename: Alex J
authors.initials: AJ
authors.lastname: Barker
authors.affiliation: Cardiovascular Division, Temple University, Philadelphia, PA, United States of America.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Forfia
authors.affiliation: Cardiovascular Division, University of Pennsylvania, Philadelphia, PA, United States of America.
authors.forename: Yuchi
authors.initials: Y
authors.lastname: Han
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology*; D005260:Female; D006352:Heart Ventricles / Q000378:metabolism / Q000503:physiopathology*; D006801:Humans; D006976:Hypertension, Pulmonary / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011651:Pulmonary Artery / Q000503:physiopathology; D018497:Ventricular Dysfunction, Right / Q000503:physiopathology*; D016278:Ventricular Function, Right / Q000502:physiology*; D055815:Young Adult