Multi-probe Vector Velocity Estimation in Deep and Large Regions of Interest: a Simulation Study

Objective: The current vector velocity measurement techniques are typically limited by probe apertures, which restrict their use to superficial vessels. This work introduces a high frame rate method based on the use of multiple array probes transmitting defocused beams and shows that such a method permits accurate and precise measurements of blood velocities in deep and large regions/volumes of interest. Methods: Multiple probes are positioned to investigate a common region of interest and activated in a sequence. The corresponding phase shifts are estimated and combined through a least square error approach to derive the velocity vector. The method's performance has been quantitatively evaluated in both 2-D and 3-D scenarios through simulations based on either two linear- or three matrix sparsearray probes. Results: Good estimations of both module (average rmse(v) 11.9% of vmax) and direction (average rmse(α) 2.3° and rmse(β) 8.0°) of the velocity vectors have been obtained. The corresponding vector velocity frames cover wide areas or volumes even around depths as high as 80 mm. Conclusions: This simulation work demonstrates that multi-probe configurations can be exploited to measure the 2-D or 3-D flow velocity accurately and precisely in deep and large regions of interest. Significance: In a clinical scenario, for example, the method could be exploited for velocity estimation in the abdominal region where large and deep vessels, such as the aorta, are located.