An MR Safe Double-Arch Needle Insertion Robot with Scissor-Folding Mechanism for Abdominal Percutaneous Interventions*

Tumors affecting abdominal organs rank among the deadliest malignancies. In this context, Magnetic Resonance Imaging (MRI) serves as an effective diagnostic tool with a strong potential to support image-guided minimally invasive interventions for treating these tumours, offering an ionizing-radiation-free medical modality. MRI provides exceptional soft tissue contrast and multi-angle imaging, enabling accurate intraoperative localisation of target tumours within these vital organs. Nevertheless, MRI-guided minimally invasive interventions still encounter significant challenges due to the strong magnetic field environment and the narrow and deep bore of MRI machines. This paper proposes a novel MR safe 5-degrees-of-freedom (DoFs) parallel table-mounted double-arch needle insertion robot with a scissor-folding mechanism (SFM) for abdominal interventions. The proposed robot is designed to fit a standard 70-cm MRI bore. Initial evaluation experiments indicate mean errors of 3.14 mm for the proposed robotic arch and 2.23 mm for the full needle insertion robot, respectively. Additionally, preliminary testing of the system in an MRI environment resulted in unaltered MRI imaging output, with negligible artefacts associated with the presence of the robot within the bore.