title: Magnetic resonance imaging 4-D flow-based analysis of aortic hemodynamics in Turner syndrome.
abstract: BACKGROUND
  Cardiovascular surveillance is important in Turner syndrome because of the increased risk of aortic dilation and dissection with consecutively increased mortality.
  
  
  OBJECTIVE
  To compare 4-D flow MRI for the characterization of aortic 3-D flow patterns, dimensions and vessel wall parameters in pediatric patients with Turner syndrome and age-matched controls.
  
  
  METHODS
  We performed 4-D flow MRI measuring in vivo 3-D blood flow with coverage of the thoracic aorta in 25 patients with Turner syndrome and in 16 female healthy controls (age mean ± standard deviation were 16 ± 5 years and 17 ± 4 years, respectively). Blood flow was visualized by time-resolved 3-D path lines. Visual grading of aortic flow in terms of helices and vortices was performed by two independent observers. Quantitative analysis included measurement of aortic diameters, quantification of peak systolic wall shear stress, pulsatility index and oscillatory shear index at eight defined sites.
  
  
  RESULTS
  Patients with Turner syndrome had significantly larger aortic diameters normalized to BSA, increased vortices in the ascending aorta and elevated helix flow in the ascending and descending aorta compared to controls (all P<0.03). Patients with abnormal helical or vortical flow in the ascending aorta had significantly larger diameters of the ascending aorta (P<0.03). Peak systolic wall shear stress, pulsatility index and oscillatory shear index were significantly lower in Turner patients compared to controls (p=0.02, p=0.002 and p=0.01 respectively).
  
  
  CONCLUSIONS
  Four-dimensional flow MRI provides new insights into the altered aortic hemodynamics and wall shear stress that could have an impact on the development of aortic dissections.
authors.affiliation: Department of Congenital Heart Disease and Pediatric Cardiology, University Medical Center Heidelberg, Im Neuenheimer Feld 430, D-69120, Heidelberg, Germany. raoul.arnold@med.uni-heidelberg.de.
authors.forename: Raoul
authors.identifier: http://orcid.org/0000-0002-7107-8046
authors.initials: R
authors.lastname: Arnold
authors.affiliation: Department of Pediatric Hematology/Oncology/Hemostaseology, University Medical Center, Mainz, Germany.
authors.forename: Marie
authors.initials: M
authors.lastname: Neu
authors.affiliation: Department of Congenital Heart Defects and Pediatric Cardiology, Heart Center, University of Freiburg, Freiburg im Breisgau, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hirtler
authors.affiliation: Department of General Pediatrics, Adolescent Medicine and Neonatology, Center for Pediatrics, Medical Center - University of Freiburg, Freiburg im Breisgau, Germany.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Gimpel
authors.affiliation: Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.|Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Chicago, IL, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Markl
authors.affiliation: Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.|Department of Radiology, University Children's Hospital, Zürich, Switzerland.
authors.forename: Julia
authors.initials: J
authors.lastname: Geiger
mesh_terms: D000293:Adolescent; D000328:Adult; D001013:Aorta, Thoracic / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D001783:Blood Flow Velocity / Q000502:physiology; D002648:Child; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D011446:Prospective Studies; D014424:Turner Syndrome / Q000503:physiopathology*; D055815:Young Adult
keywords: 4-D flow; Adolescents; Aorta; Hemodynamics; Magnetic resonance imaging; Turner syndrome; Wall shear stress