Robotic ultrasound has the potential to assist and guide physicians during interventions. In this work, we present a set of methods and a workflow to enable autonomous MRI-guided ultrasound acquisitions. Our approach uses a structured-light 3D scanner for patient-to-robot and image-to-patient calibration, which in turn is used to plan 3D ultrasound trajectories. These MRI-based trajectories are followed autonomously by the robot and are further refined online using automatic MRI/US registration. Despite the low spatial resolution of structured light scanners, the initial planned acquisition path can be followed with an accuracy of 2.46 +/- 0.96 mm. This leads to a good initialization of the MRI/US registration: the 3D-scan-based alignment for planning and acquisition shows an accuracy (distance between planned ultrasound and MRI) of 4.47 mm, and 0.97 mm after an online-update of the calibration based on a closed loop registration.
@article{arxiv.1607.08371,
title = {Towards MRI-Based Autonomous Robotic US Acquisitions: A First Feasibility Study},
author = {Christoph Hennersperger and Bernhard Fuerst and Salvatore Virga and Oliver Zettinig and Benjamin Frisch and Thomas Neff and Nassir Navab},
journal= {arXiv preprint arXiv:1607.08371},
year = {2016}
}