Method for estimating uncertainty in individual vector-flow-mapping measurements

An experimental validation system for vector-flow-mapping (VFM) has been developed to verify the VFM accuracy. A VFM measured by ultrasound is a mapping of 2D flow vector fields in the human heart. The validation system consists of a left ventricle (LV) phantom, a stereo particle image velocimetry (stereo-PIV), and an ultrasound scanner. The LV phantom is pulsated by controlling the external pressure. The optically transparent LV phantom enables the PIV to obtain velocity fields. To evaluate the degradation of VFM accuracy in a 3D flow, the VFM results are compared with those obtained from the stereo-PIV, which provides accurate 3D velocity components in a plane. Preliminary results suggest that the VFM and PIV vector fields are in good agreement. However, 3D flow, which resulted from the VFM errors, are also observed in the phantom. A novel method for estimating uncertainty in individual VFM measurements was proposed by considering the velocity discrepancy between VFM and tissue tracking at the LV wall. The VFM error estimated with the proposed method was validated by comparing it with that measured using the PIV. The estimated errors agreed with the measured error from the PIV. The mean difference was about 8% in the experiments.