title: Real-time phase-contrast flow MRI of the ascending aorta and superior vena cava as a function of intrathoracic pressure (Valsalva manoeuvre).
abstract: OBJECTIVE
  Real-time phase-contrast flow MRI at high spatiotemporal resolution was applied to simultaneously evaluate haemodynamic functions in the ascending aorta (AA) and superior vena cava (SVC) during elevated intrathoracic pressure (Valsalva manoeuvre).
  
  
  METHODS
  Real-time phase-contrast flow MRI at 3 T was based on highly undersampled radial gradient-echo acquisitions and phase-sensitive image reconstructions by regularized non-linear inversion. Dynamic alterations of flow parameters were obtained for 19 subjects at 40-ms temporal resolution, 1.33-mm in-plane resolution and 6-mm section thickness. Real-time measurements were performed during normal breathing (10 s), increased intrathoracic pressure (10 s) and recovery (20 s).
  
  
  RESULTS
  Real-time measurements were technically successful in all volunteers. During the Valsalva manoeuvre (late strain) and relative to values during normal breathing, the mean peak flow velocity and flow volume decreased significantly in both vessels (p < 0.001) followed by a return to normal parameters within the first 10 s of recovery in the AA. By contrast, flow in the SVC presented with a brief (1-2 heartbeats) but strong overshoot of both the peak velocity and blood volume immediately after pressure release followed by rapid normalization.
  
  
  CONCLUSIONS
  Real-time phase-contrast flow MRI may assess cardiac haemodynamics non-invasively, in multiple vessels, across the entire luminal area and at high temporal and spatial resolution.
  
  
  CONCLUSIONS
  Future clinical applications of this technique promise new insights into haemodynamic alterations associated with pre-clinical congestive heart failure or diastolic dysfunction, especially in cases where echocardiography is technically compromised.
authors: 1 Institute for Diagnostic and Interventional Radiology, Heart Center, University Medical Center Göttingen, Göttingen, Germany.
authors: J T
authors: JT
authors: Kowallick
authors: A A
authors: AA
authors: Joseph
authors: C
authors: C
authors: Unterberg-Buchwald
authors: M
authors: M
authors: Fasshauer
authors: K
authors: K
authors: van Wijk
authors: K D
authors: KD
authors: Merboldt
authors: D
authors: D
authors: Voit
authors: J
authors: J
authors: Frahm
authors: J
authors: J
authors: Lotz
authors: J M
authors: JM
authors: Sohns
mesh_terms: D000328:Adult; D001011:Aorta / Q000502:physiology*; D001783:Blood Flow Velocity; D001794:Blood Pressure; D001810:Blood Volume; D005260:Female; D006321:Heart / Q000503:physiopathology; D006439:Hemodynamics; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014636:Valsalva Maneuver; D014683:Vena Cava, Superior / Q000502:physiology*; D055815:Young Adult