Accurate and Reproducible Mitral Valvular Blood Flow Measurement with Three?Directional Velocity?Encoded Magnetic Resonance Imaging

Abstract

A new method for quantifying the transvalvular flow through the mitral valve (MV) based on three-directional velocity-encoded magnetic resonance imaging (MRI) is presented. For thirty time phases during one cardiac cycle, the three-dimensional (3D) velocity vector field of the blood flow is reconstructed from the MRI measurement. Retrospectively, for each time phase, the MV-plane is indicated manually in the velocity data and the flow through this plane is determined, representing the MV flow. Measurements are performed in 10 healthy volunteers. The new method is compared to the conventional, one-directional velocity-encoded MRI method for which an acquisition plane is positioned at the mitral valve at end-systole and remains fixed during the acquisition. The flow measurements with the new method correlate very well with the flow measured in the aorta (r(p)=0.92, p<0.01), whereas the conventional method shows no statistically significant correlation (r(p)=0.15, p=0.68). The low differences between the flow measured at the MV and the flow in the aorta proves high accuracy of the new method. Also, the new method shows very low intra- and interobserver variation, proving the high reproducibility. Three-directional velocity-encoded MRI is a patient-friendly and easy-to-use method suitable for quantifying accurately and reproducibly the transvalvular MV flow.

Quantification of Functional Mitral Regurgitation by Real-Time 3D Echocardiography

“…However, conventional single-slice 1-directional VE-CMR showed some limitations (21), in particular because the acquisition plane cannot be adapted to the motion of the valve, and currently the most accurate approach is considered the 3D 3-directional VE-CMR with retrospective valve tracking. This technique is able to cover the complete velocity vector field of the blood flow and to correct for the through-plane myocardial motion in the apical-basal direction (22,23). Furthermore, it has been validated in vitro with flow phantoms and in vivo and showed excellent reproducibility (24).…”

“…Recently, velocity-encoded cardiac magnetic resonance (VE-CMR) has been proposed as a reference method for transvalvular flow quantification (19,20); in particular, the use of a 3-dimensional (3D) 3-directional acquisition has been shown to be able to optimize the conventional 2D 1-directional acquisition (21)(22)(23)(24), providing independent MR flow quantification. Therefore, the aim of the current study was to explore in patients with functional MR, the feasibility and accuracy of direct measurement of EROA and quantification of Rvol with RT3DE, in a head-to-head comparison with VE-CMR.…”

Quantitative Assessment of Mitral Regurgitation

“…The accuracy of flow measurement with MRI has been demonstrated in several in vitro studies and invasive in vivo measurements. 22,28 Therefore, although it may be debatable, MRI may be considered one of the reference methods to evaluate the accuracy of other imaging techniques in the assessment of regurgitant valvular lesions.…”

Flow Assessment Through Four Heart Valves Simultaneously Using 3-Dimensional 3-Directional Velocity-Encoded Magnetic Resonance Imaging With Retrospective Valve Tracking in Healthy Volunteers and Patients With Valvular Regurgitation

“…14 In fact, previous studies showed no conservation of mass and moderate correlations between stroke volume through the mitral valve (MV) and tricuspid valve (TV) and stroke volume measured in the ascending aorta. 15, 16 Kozerke et al 17 introduced the Slice Track-method where prior to VE MRI, the basal level of the left ventricle was labeled in the septum and the lateral wall and the excursion of the basal level determined the positioning and angulation of the acquisition. This technique makes use of navigator with prospective triggering for cardiac synchronization.…”