Longitudinal motion of the carotid artery wall and speckle decorrelation issue: Accurate estimation using a Kalman-based speckle tracking method

This work presents an original 2D motion estimation framework, applied to the carotid artery in ultrasound B mode sequences. Our method is based on a specific block matching approach, in which the reference block is updated in each frame by a Kalman filtering scheme. Applied in vivo to a cohort of 28 subjects, our method showed a high robustness and accuracy, with a mean absolute error of 47 ± 39 μm and 18 ± 14 μm for the trajectory estimation, and 55 ± 55 μm and 26 ± 22 μm for the amplitude estimation, in the longitudinal and radial directions, respectively. This corresponded to the magnitude of the inter- and intra-observers variability, and was significantly inferior in comparison with two other methods, i.e. a classical block matching implementation, and the Velocity Vector Imaging commercial software. Our method was also fully reproducible as the resulting variability was null. The proposed framework may constitute a reliable method to assess the arterial stiffness.