Martin Barva, Jan Kybic, Vaclav Hlavac: Localizing Metal Electrode from 3D Ultrasound Data Using RANSAC and Intensity Priors

In surgical interventions, miniature metallic tools such as thin electrodes and needles are introduced in tissue. Tracking systems are used to estimate their precise position. In this paper we describe an algorithm that exploits a three-dimensional ultrasound image and raw radio-frequency (RF) signal to determine the position of a thin, metallic electrode in biological tissue. We assume that electrode appears in 3D ultrasound image as a bright, elongated region. To estimate its position, a mathematical model of the region was established. It approximates the electrode axis with a polynomial curve. The voxel intensity distribution near the ray axis was determined from acquired RF signals. The model parameters are estimated by the RANSAC estimator. Finally, the electrode endpoints are located. The method was tested on real ultrasound data of a phantom with a thin metal electrode inserted. The results of experiments show that the method is stable even if the data are noisy.