An MRI-guided stereotactic neurosurgical robotic system for semi-enclosed head coils

Magnetic resonance imaging (MRI) offers high-quality soft tissue imaging without radiation exposure, which allows stereotactic techniques to significantly improve outcomes in cranial surgeries, particularly in deep brain stimulation (DBS) procedures. However, conventional stereotactic neurosurgeries often rely on mechanical stereotactic head frames and preoperative imaging, leading to suboptimal results due to the invisibility and the contact with patient's head, which may cause additional harm. This paper presents a frameless, MRI-guided stereotactic neurosurgical robotic system. The robot features a seven-degree-of-freedom (7-DOF) remote center of motion, with five DOFs for preoperative trajectory alignment to the target lesion and two DOFs for defining the depth and twisting motion of the needle during insertion, thus to minimize tissue damage. The system employs interactive MRI guidance for real-time visualization of the puncture process, showing great potential in reducing surgery time, enhancing targeting accuracy, and improving safety. Experiments were conducted on the proposed system to evaluate signal-to-noise ratio (SNR) and geometric distortion. During the simultaneous operation and imaging, the system demonstrated less than 10.02% SNR attenuation and less than 0.1% geometric distortion, ensuring image usability. The free-space positioning accuracy of the system was evaluated using a laser tracker, revealing a tip position repeatability error within 0.3 ± 0.1 mm.