  Intraventricular vector flow mapping (iVFM) is a technique for retrieving 2-D
velocity vector fields of blood flow in the left ventricle. This method is
based on conventional color Doppler imaging, which makes iVFM compatible with
the clinical setting. We have generalized the iVFM for a three-dimensional
reconstruction (3D-iVFM). 3D-iVFM is able to recover three-component velocity
vector fields in a full intraventricular volume by using a clinical
echocardiographic triplane mode. As with the 2-D version, the method is based
on the mass conservation, and free-slip boundary conditions on the endocardial
wall. These mechanical constraints were imposed in a least-squares minimization
problem that was solved through the method of Lagrange multipliers. We
validated 3D-iVFM in silico in a patient-specific CFD (computational fluid
dynamics) model of cardiac flow, and tested its feasibility in vivo on
volunteers. In both in silico and in vivo investigations, the dynamics of the
intraventricular vortex that forms during diastole was deciphered by 3D-iVFM.
Our results tend to indicate that 3D-iVFM could provide full-volume
echocardiographic information on left intraventricular hemodynamics from the
clinical modality of triplane color Doppler.
