Optical flow-based motion estimation of ultrasonic images for force estimation in percutaneous procedures: Theory and experimental validation

In recent years, there hass been a pronounced emphasis on percutaneous needle steering with the aid of advanced soft tissue modeling techniques. In this work an optical flow based motion estimation method is used to estimate the force applied to the needle by the soft tissue during percutaneous applications. The study considers Finite Element Model (FEM) of the tissue evaluated by the deformation data acquired through the optical flow method. To represent the soft tissue behavior, dynamic FEM with Rayleigh damping and viscoelastic models are used. The method is validated experimentally through offline evaluation of the ultrasonic images of the chicken breast punctured by a needle. The force applied to the needle is measured through a force sensor situated externally at the distal end of the needle shaft. Measured data from the force sensor is compared with the result of the proposed method. It is shown that both tissue models are effectively able to estimate the force.