title: Inlet and outlet valve flow and regurgitant volume may be directly and reliably quantified with accelerated, volumetric phase-contrast MRI.
abstract: OBJECTIVE
  To determine whether it is feasible to use solely an accelerated 4D phase-contrast magnetic resonance imaging (4D-PC MRI) acquisition to quantify net and regurgitant flow volume through each of the cardiac valves.
  
  
  METHODS
  Accelerated, 4D-PC MRI examinations performed between March 2010 through June 2011 as part of routine MRI examinations for congenital, structural heart disease were retrospectively reviewed and analyzed using valve-tracking visualization and quantification algorithms developed in Java and OpenGL. Excluding patients with transposition or single ventricle physiology, a total of 34 consecutive pediatric patients (19 male, 15 female; mean age 6.9 years; age range 10 months to 15 years) were identified. 4D-PC flow measurements were compared at each valve and against routine measurements from conventional cardiac MRI using Bland-Altman and Pearson correlation analysis.
  
  
  RESULTS
  Inlet and outlet valve net flow were highly correlated between all valves (P = 0.940-0.985). The sum of forward flow at the outlet valve and regurgitant flow at the inlet valve were consistent with volumetric displacements in each ventricle (P = 0.939-0.948). These were also highly consistent with conventional planar MRI measurements with net flow (P = 0.923-0.935) and regurgitant fractions (P = 0.917-0.972) at the outlet valve and ventricular volumes (P = 0.925-0.965).
  
  
  CONCLUSIONS
  It is possible to obtain consistent measurements of net and regurgitant blood flow across the inlet and outlet valves relying solely on accelerated 4D-PC. This may facilitate more efficient clinical quantification of valvular regurgitation.
authors.affiliation: Department of Radiology, Stanford University, Stanford, California, USA.
authors.forename: Albert
authors.initials: A
authors.lastname: Hsiao
authors.forename: Umar
authors.initials: U
authors.lastname: Tariq
authors.forename: Marcus T
authors.initials: MT
authors.lastname: Alley
authors.forename: Michael
authors.initials: M
authors.lastname: Lustig
authors.forename: Shreyas S
authors.initials: SS
authors.lastname: Vasanawala
mesh_terms: D000293:Adolescent; D000465:Algorithms; D002648:Child; D002675:Child, Preschool; D005240:Feasibility Studies; D005260:Female; D006330:Heart Defects, Congenital / Q000503:physiopathology*; D006349:Heart Valve Diseases / Q000151:congenital* / Q000503:physiopathology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007223:Infant; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D012189:Retrospective Studies
keywords: flow; mitral; regurgitation; structural; tricuspid