Computer-guided ultrasound probe realignment by optical tracking

Abstract

In longitudinal studies and localized therapies, tissue changes are commonly tracked by repeated ultrasound scans at a fixed location marked on the patient body. However, the accuracy of this probe realignment approach is sometimes inadequate, especially when maintaining the insonification angle is essential. This paper describes a system that provides real-time visual guidance for accurate realignment of the ultrasound probe in six degrees of freedom (6 DoF). This system uses a small camera rigidly mounted on the probe to track artificial skin features, from which the current probe pose relative to the target pose is estimated. A virtual pyramid is created in the skin map and shown in the camera frame to intuitively indicate the probe movement required to achieve the target pose. Performance of this system was examined in vivo, and it was shown that this system significantly improves alignment of tissue structures in repeated ultrasound scans.