Evaluation of Left Ventricular Flow Propagation Velocity from Multi-Dimensional Cardiac Imaging*

We introduce a new method to evaluate the left ventricular (LV) diastolic flow propagation from cardiac flow imaging. The proposed method estimates the local and instantaneous flow propagation velocity (V_prop) by fitting the first order wave equation to the velocity gradients with weighted least-squares. The proposed method was validated using the synthetic vortex ring flow data. The V_prop estimated from multi-dimensional data has about 50% less error than the V_prop from one-dimensional data. The method was first applied to the velocity fields acquired with two-dimensional phase-contrast magnetic resonance imaging (pc-MRI) and 4D flow MRI and provided the spatial distribution and the temporal evolution of V_prop during the LV diastole. During early diastole, the timing of peak flow propagation coincides with the peak intraventricular pressure difference. The flow propagation towards the apex is mainly located at the front of the inflow jet and downstream of the vortex ring formed near mitral valve tips. The proposed method provides a more comprehensive investigation and potentially improves the evaluation of LV diastolic function.