A Stiffness Adjustable 6-DOF Robotic System for Pituitary Tumor Resection Under MRI

Magnetic resonance imaging offers better visualization for tumors present in the delicate parts of the human body. A pituitary tumor is one of the common types of brain-related tumors located underside the brain. It can be accessed through the nostrils and visualized better using magnetic resonance imaging (MRI). In this work, we present a 6-degree-of-freedom (DOF) robotic system for pituitary tumor resection via a transsphenoidal approach designed specifically for a commercially available 3T MRI scanner. The robotic system is designed to follow the anatomical and surgical constraints and to work inside the bore of the MRI to allow image acquisition during the surgical procedure. It has a 6-DOF manipulator consisting of a concentric tube and a tendon-driven bendable section. Both mechanisms are merged to have stiffness changing capability, and payload capacity to aid the surgical task. The manipulator is attached to a flexure shaft to bend it at the desired surgical angles. The materials used for development are analyzed in MRI and exhibit signal-noise ratio (SNR) reduction of less than 10%. The experimental results show that the stiffness can be changed more than ten times for safe navigation to the surgical site without damaging the surrounding tissues. Also, it can provide a maximum lifting force of more than 2N. The presented system is the preliminary version of the pituitary tumor resection system under development and shows the feasibility to be used in a real surgical environment.