O. Zettinig, B. Frisch, S. Virga, M. Esposito, A. Rienmüller, B. Meyer, C. Hennersperger, Y.-M. Ryang , N. Navab 3D Ultrasound Registration-based Visual Servoing for Neurosurgical Navigation International Journal of Computer Assisted Radiology and Surgery, Volume 12, Issue 9, pp 1607–1619, 2017. The original publication is available online at link.springer.com (bib)
	Purpose We present a fully image-based visual servoing framework for neurosurgical navigation and needle guidance. The proposed servo-control scheme allows for compensation of target anatomy movements, maintaining high navigational accuracy over time, and automatic needle guide alignment for accurate manual insertions. Method: Our system comprises a motorized 3D ultrasound (US) transducer mounted on a robotic arm and equipped with a needle guide. It continuously registers US sweeps in real-time with a pre-interventional plan based on CT or MR images and annotations. While a visual control law maintains anatomy visibility and alignment of the needle guide, a force controller is employed for acoustic coupling and tissue pressure. We validate the servoing capabilities of our method on a geometric gel phantom and real human anatomy, and the needle targeting accuracy using CT images on a lumbar spine gel phantom under neurosurgery conditions. Results: Despite the varying resolution of the acquired 3D sweeps, we achieved direction-independent positioning errors of 0.35+/-0.19mm and 0.61+/-0.45deg, respectively. Our method is capable of compensating movements of around 25mm/s and works reliably on human anatomy with errors of 1.45+/-0.78mm. In all four manual insertions by an expert surgeon, a needle could be successfully inserted into the facet joint, with an estimated targeting accuracy of 1.33+/-0.33mm, superior to the gold standard. Conclusion: The experiments demonstrated the feasibility of robotic ultrasound-based navigation and needle guidance for neurosurgical applications such as lumbar spine injections.
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