Towards MRI guided surgical manipulator

Abstract

Background: The advantages of surgical robots and manipulators are well recognized in the clinical and technical community. Precision, accuracy and the potential for telesurgery are the prime motivations in applying advanced robot technology in surgery. In this paper critical interactions between Magnetic Resonance Imaging equipment and mechatronic devices are discussed and a novel Magnetic Resonance compatible surgical robot is described.

Material and methods: Experimental results of the effects from several passive (metallic materials) and active (ultrasound motors) mechanical elements are demonstrated. The design principles for Magnetic Resonance compatible robots are established and the compatibility of the proposed robot is assessed by comparing images taken with and without the robot's presence within Signa SP/I GE Medical Systems scanner.

Results: The results showed that, in principle, it is possible to construct precision mechatronic devices intended to operate inside MR scanner. Use of such a device will not cause image shift or significant degradation of signal-to-noise-ratio. An MR compatible surgical assist robot was designed and constructed. The robot is not affected by the presence of strong magnetic fields and is able to manoeuvre during imaging without compromising the quality of images. A novel image-guided robot control scheme was proposed. As a part of the control scheme, biomechanics-based organ deformation model was constructed and validated by in-vivo experiment. It has been recognised that for robust control of an image guided surgical robot the precise knowledge of the mechanical properties of soft organs operated on must be known. As an illustration, results in mathematical modelling and computer simulation of brain deformation are given.

Conclusion: The novel MR compatible robot was designed to position and direct an axisymmetric tool, such as a laser pointer or a biopsy catheter. New Robot control system based on the prediction of soft organ deformation was proposed.