title: Time-resolved magnetic resonance angiography and flow-sensitive 4-dimensional magnetic resonance imaging at 3 Tesla for blood flow and wall shear stress analysis.
abstract: OBJECTIVE
  In light of the ongoing discussion about flow-mediated arterial remodeling, it was the aim of this report to demonstrate the detailed assessment of 3-dimensional vascular hemodynamics by high-field magnetic resonance imaging in healthy volunteers and to illustrate its potential in comparison with results in a patient with stenosis.
  
  
  METHODS
  All examinations consisted of flow-sensitive 4-dimensional magnetic resonance imaging at 3 Tesla. Retrospective blood flow visualization and segmental quantification of wall shear stress and oscillatory shear index were performed. The results from 11 healthy individuals were compared with a 13-year-old patient with aortic stenosis who received a combined protocol with time-resolved 3-dimensional magnetic resonance angiography before and 5 and 9 months after intervention.
  
  
  RESULTS
  Evaluation of normal blood flow characteristics demonstrated predominantly right-handed helical flow in the ascending aorta. Vortex formation was observed in 1 of 11 volunteers. Consistently high segmental wall shear stress was found along the circumference of the ascending aorta (average wall shear stress = 0.191 +/- 0.06 N/m(2)) and descending aorta (average 0.191 +/- 0.06 N/m(2)). Compared with volunteers, the patient revealed substantial flow changes proximal and distal to the stenosis. Blood flow alterations in the ascending aorta were also observed associated with changes in velocities and wall shear stress that gradually normalized after intervention.
  
  
  CONCLUSIONS
  Flow-sensitive 4-dimensional magnetic resonance imaging at 3 Tesla can provide deeper insights into hemodynamic alterations in the diagnosis and follow-up of aortic pathologies. These findings indicate the potential of the methodology for the evaluation of effects of localized pathologies on the entire vascular system, which will have to be confirmed in future studies.
authors.affiliation: Department of Diagnostic Radiology and Medical Physics, University Hospital Freiburg, Freiburg, Germany. alex.frydrychowicz@uniklinik-freiburg.de
authors.forename: Alex
authors.initials: A
authors.lastname: Frydrychowicz
authors.forename: Alexander
authors.initials: A
authors.lastname: Berger
authors.forename: Maximilan F
authors.initials: MF
authors.lastname: Russe
authors.forename: Aurélien F
authors.initials: AF
authors.lastname: Stalder
authors.forename: Andreas
authors.initials: A
authors.lastname: Harloff
authors.forename: Sven
authors.initials: S
authors.lastname: Dittrich
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hennig
authors.forename: Mathias
authors.initials: M
authors.lastname: Langer
authors.forename: Michael
authors.initials: M
authors.lastname: Markl
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001011:Aorta / Q000502:physiology* / Q000503:physiopathology; D001024:Aortic Valve Stenosis / Q000503:physiopathology / Q000601:surgery; D001783:Blood Flow Velocity; D003287:Contrast Media; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D018810:Magnetic Resonance Angiography; D008297:Male; D033081:Shear Strength
chemical_list: D003287:Contrast Media