title: Four-dimensional velocity-encoded magnetic resonance imaging improves blood flow quantification in patients with complex accelerated flow.
abstract: OBJECTIVE
  To evaluate the use of four-dimensional (4D) velocity-encoded magnetic resonance imaging (VEC MRI) for blood flow quantification in patients with semilunar valve stenosis and complex accelerated flow.
  
  
  METHODS
  Peak velocities (Vmax) and stroke volumes (SV) were quantified by 2D and 4D VEC MRI in volunteers (n = 7) and patients with semilunar valve stenosis (n = 18). Measurements were performed above the aortic and pulmonary valve with both techniques and, additionally, at multiple predefined planes in the ascending aorta and in the pulmonary trunk within the 4D dataset. In patients, 4D VEC MRI streamline analysis identified flow patterns and regions of highest flow velocity (4D(max-targeted)) for further measurements and Vmax was also measured by Doppler-echocardiography.
  
  
  RESULTS
  In patients, 4D VEC MRI showed higher Vmax than 2D VEC MRI (2.7 ± 0.6 m/s vs. 2.4 ± 0.5 m/s, P < 0.03) and was more comparable to Doppler-echocardiography (2.8 ± 0.7 m/s). 4D(max-targeted) revealed highest Vmax values (3.1 ± 0.6 m/s). SV measurements showed significant differences between different anatomical levels in the ascending aorta in patients with complex accelerated flow, whereas differences in volunteers with laminar flow patterns were negligible (P = 0.004).
  
  
  CONCLUSIONS
  4D VEC MRI improves MRI-derived blood flow quantification in patients with semilunar valve stenosis and complex accelerated flow.
authors.affiliation: Deutsches Herzzentrum Berlin, Unit of Cardiovascular Imaging, Department of Congenital Heart Disease and Pediatric Cardiology, Berlin, Germany. snordmeyer@dhzb.de
authors.forename: Sarah
authors.initials: S
authors.lastname: Nordmeyer
authors.forename: Eugénie
authors.initials: E
authors.lastname: Riesenkampff
authors.forename: Daniel
authors.initials: D
authors.lastname: Messroghli
authors.forename: Siegfried
authors.initials: S
authors.lastname: Kropf
authors.forename: Johannes
authors.initials: J
authors.lastname: Nordmeyer
authors.forename: Felix
authors.initials: F
authors.lastname: Berger
authors.forename: Titus
authors.initials: T
authors.lastname: Kuehne
mesh_terms: D000328:Adult; D000368:Aged; D016880:Anisotropy; D001011:Aorta / Q000473:pathology; D001021:Aortic Valve / Q000473:pathology; D001783:Blood Flow Velocity; D003251:Constriction, Pathologic / Q000473:pathology; D015150:Echocardiography, Doppler / Q000379:methods; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000473:pathology; D011664:Pulmonary Valve / Q000473:pathology; D013318:Stroke Volume