In vivo out-of-plane Doppler imaging based on ultrafast plane wave imaging

Retrieving the blood flow velocity vector on 2D acquisitions transverse to the vessel could improve the quantification of flow rate in large vessels. The in plane component is easily computed using the Doppler frequency shift. The main problem is to retrieve the angle between the probe imaging plane and the vessel axis to compute the out of plane component. Here, we study the case where the speed vector can be decomposed on two directions: the out of plane direction and the depth direction. We explore the combination of a technique called spectral broadening with ultrafast plane wave imaging. Due to its high spatio temporal sampling, ultrafast plane wave imaging permits to quantify the Doppler spectrum of flows in each pixel. Moreover, ultrafast plane wave imaging permits a fast calibration method of Doppler spectra spectral broadening avoiding approximations of a complex theoretical analysis. An experimental demonstration of the method is performed in vivo on healthy human carotid artery.