title: Fast measurements of flow through mitral regurgitant orifices with magnetic resonance phase velocity mapping.
abstract: Magnetic-resonance (MR) phase velocity mapping (PVM) shows promise in measuring the mitral regurgitant volume. However, in its conventional nonsegmented form, MR-PVM is slow and impractical for clinical use. The aim of this study was to evaluate the accuracy of rapid, segmented k-space MR-PVM in quantifying the mitral regurgitant flow through a control volume (CV) method. Two segmented MR-PVM schemes, one with seven (seg-7) and one with nine (seg-9) lines per segment, were evaluated in acrylic regurgitant mitral valve models under steady and pulsatile flow. A nonsegmented (nonseg) MR-PVM acquisition was also performed for reference. The segmented acquisitions were considerably faster (<10 min) than the nonsegmented (>45 min). The regurgitant flow rates and volumes measured with segmented MR-PVM agreed closely with those measured with nonsegmented MR-PVM (differences <5%, p > 0.05), when the CV was large enough to exclude the region of flow acceleration and aliasing from its boundaries. The regurgitant orifice shape (circular vs. slit-like) and the presence of aortic outflow did not significantly affect the accuracy of the results under both steady and pulsatile flow (p > 0.05). This study shows that segmented k-space MR-PVM can accurately quantify the flow through regurgitant orifices using the CV method and demonstrates great clinical potential.
authors.affiliation: Laboratory of Biofluid Mechanics and Cardiovascular Imaging, Department of Chemical and Biomedical Engineering, Cleveland State University, Cleveland, OH 44115-2425, USA.
authors.forename: Haosen
authors.initials: H
authors.lastname: Zhang
authors.forename: Sandra S
authors.initials: SS
authors.lastname: Halliburton
authors.forename: Richard D
authors.initials: RD
authors.lastname: White
authors.forename: George P
authors.initials: GP
authors.lastname: Chatzimavroudis
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008943:Mitral Valve; D008955:Models, Cardiovascular; D011673:Pulsatile Flow; D015203:Reproducibility of Results