title: Non-invasive assessment of cardiac function and pulmonary vascular resistance in an canine model of acute thromboembolic pulmonary hypertension using 4D flow cardiovascular magnetic resonance.
abstract: BACKGROUND
  The purpose of this study was to quantify right (RV) and left (LV) ventricular function, pulmonary artery flow (QP), tricuspid valve regurgitation velocity (TRV), and aorta flow (QS) from a single 4D flow cardiovascular magnetic resonance (CMR) (time-resolved three-directionally motion encoded CMR) sequence in a canine model of acute thromboembolic pulmonary hypertension (PH).
  
  
  METHODS
  Acute PH was induced in six female beagles by microbead injection into the right atrium. Pulmonary arterial (PAP) and pulmonary capillary wedge (PCWP) pressures and cardiac output (CO) were measured by right heart catheterization (RHC) at baseline and following induction of acute PH. Pulmonary vascular resistance (PVRRHC) was calculated from RHC values of PAP, PCWP and CO (PVRRHC = (PAP-PCWP)/CO). Cardiac magnetic resonance (CMR) was performed on a 3 T scanner at baseline and following induction of acute PH. RV and LV end-diastolic (EDV) and end-systolic (ESV) volumes were determined from both CINE balanced steady-state free precession (bSSFP) and 4D flow CMR magnitude images. QP, TRV, and QS were determined from manually placed cutplanes in the 4D flow CMR flow-sensitive images in the main (MPA), right (RPA), and left (LPA) pulmonary arteries, the tricuspid valve (TRV), and aorta respectively. MPA, RPA, and LPA flow was also measured using two-dimensional flow-sensitive (2D flow) CMR.
  
  
  RESULTS
  Biases between 4D flow CMR and bSSFP were 0.8 mL and 1.6 mL for RV EDV and RV ESV, respectively, and 0.8 mL and 4 mL for LV EDV and LV ESV, respectively. Flow in the MPA, RPA, and LPA did not change after induction of acute PAH (p = 0.42-0.81). MPA, RPA, and LPA flow determined with 4D flow CMR was significantly lower than with 2D flow (p < 0.05). The correlation between QP/TRV and PVRRHC was 0.95. The average QP/QS was 0.96 ± 0.11.
  
  
  CONCLUSIONS
  Using both magnitude and flow-sensitive data from a single 4D flow CMR acquisition permits simultaneous quantification of cardiac function and cardiopulmonary hemodynamic parameters important in the assessment of PH.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Roldán-Alzate
authors.forename: Alex
authors.initials: A
authors.lastname: Frydrychowicz
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Johnson
authors.forename: Heidi
authors.initials: H
authors.lastname: Kellihan
authors.forename: Naomi C
authors.initials: NC
authors.lastname: Chesler
authors.forename: Oliver
authors.initials: O
authors.lastname: Wieben
authors.affiliation: Department of Radiology, Clinical Science Center, University of Wisconsin - Madison, 600 Highland Avenue, Madison, Wisconsin 53792-3252, USA. cfrancois@uwhealth.org.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: François
mesh_terms: D000208:Acute Disease; D000818:Animals; D001011:Aorta / Q000503:physiopathology; D001783:Blood Flow Velocity; D006328:Cardiac Catheterization; D004195:Disease Models, Animal; D004285:Dogs; D005240:Feasibility Studies; D005260:Female; D006976:Hypertension, Pulmonary / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging; D011237:Predictive Value of Tests; D011651:Pulmonary Artery / Q000503:physiopathology*; D011652:Pulmonary Circulation; D011655:Pulmonary Embolism / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D012039:Regional Blood Flow; D014261:Tricuspid Valve / Q000503:physiopathology; D014262:Tricuspid Valve Insufficiency / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D014655:Vascular Resistance; D018497:Ventricular Dysfunction, Right / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D016277:Ventricular Function, Left; D016278:Ventricular Function, Right