title: Time-resolved three-dimensional magnetic resonance velocity mapping of aortic flow in healthy volunteers and patients after valve-sparing aortic root replacement.
abstract: OBJECTIVE
  To provide more complete characterization of ascending aortic blood flow, including vortex formation behind the valve cusps, in healthy subjects and patients after valve-sparing aortic root replacement (David reimplantation).
  
  
  METHODS
  Time-resolved 3-dimensional magnetic resonance imaging velocity mapping was performed to analyze pulsatile blood flow by using encoded 3-directional vector fields in the thoracic aortas of 10 volunteers and 12 patients after David reimplantation using a cylindrical tube graft (T. David I) and two versions of neosinus recreation (T. David-V and T. David-V-S mod ). Aortic flow was evaluated by using 3-dimensional time-resolved particle traces and velocity vector fields reformatted onto 2-dimensional planes. Semiquantitative data were derived by using a blinded grading system (0-3: 0, none; 1, minimal; 2, medium; 3, prominent) to analyze the systolic vortex formation behind the cusps, as well as retrograde and helical flow in the ascending aorta.
  
  
  RESULTS
  Systolic vortices were seen in both coronary sinuses of all volunteers (greater in the left sinus [2.5 +/- 0.5] than the right [1.8 +/- 0.8]) but in only 4 of 10 noncoronary sinuses (0.7 +/- 0.9). Comparable coronary vortices were detected in all operated patients. Vorticity was minimal in the noncoronary cusp in T. David-I repairs (0.7 +/- 0.7) but was prominent in T. David-V noncoronary graft pseudosinuses (1.5 +/- 0.6; P = .035). Retrograde flow (P = .001) and helicity (P = .028) were found in all patients but were not distinguishable from normal values in the T. David-V-S mod patients.
  
  
  CONCLUSIONS
  Coronary cusp vorticity was preserved after David reimplantation, regardless of neosinus creation. Increased retrograde flow and helicity were more prominent in T. David-V patients. These novel magnetic resonance imaging methods can assess the clinical implications of altered aortic flow dynamics in patients undergoing various types of valve-sparing aortic root replacement.
authors.affiliation: Department of Radiology, Stanford University, CA 94304, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Markl
authors.forename: Mary T
authors.initials: MT
authors.lastname: Draney
authors.forename: D Craig
authors.initials: DC
authors.lastname: Miller
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Levin
authors.forename: Eric E
authors.initials: EE
authors.lastname: Williamson
authors.forename: Norbert J
authors.initials: NJ
authors.lastname: Pelc
authors.forename: David H
authors.initials: DH
authors.lastname: Liang
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Herfkens
mesh_terms: D000328:Adult; D001011:Aorta / Q000502:physiology*; D001018:Aortic Diseases / Q000175:diagnosis* / Q000503:physiopathology* / Q000601:surgery; D001783:Blood Flow Velocity / Q000502:physiology; D019917:Blood Vessel Prosthesis Implantation; D005260:Female; D006439:Hemodynamics; D006801:Humans; D021621:Imaging, Three-Dimensional; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D011673:Pulsatile Flow / Q000502:physiology; D013997:Time Factors