Soft robotic manipulator for intraoperative MRI-guided transoral laser microsurgery

Abstract

Magnetic resonance (MR) imaging (MRI) provides compelling features for the guidance of interventional procedures, including high-contrast soft tissue imaging, detailed visualization of physiological changes, and thermometry. Laser-based tumor ablation stands to benefit greatly from MRI guidance because 3D resection margins alongside thermal distributions can be evaluated in real time to protect critical structures while ensuring adequate resection margins. However, few studies have investigated the use of projection-based lasers like those for transoral laser microsurgery, potentially because dexterous laser steering is required at the ablation site, raising substantial challenges in the confined MRI bore and its strong magnetic field. Here, we propose an MR-safe soft robotic system for MRI-guided transoral laser microsurgery. Owing to its miniature size (Ø12 × 100 mm), inherent compliance, and five degrees of freedom, the soft robot ensures zero electromagnetic interference with MRI and enables safe and dexterous operation within the confined oral and pharyngeal cavities. The laser manipulator is rapidly fabricated with hybrid soft and hard structures and is powered by microvolume (<0.004 milliter) fluid flow to enable laser steering with enhanced stiffness and lowered hysteresis. A learning-based controller accommodates the inherent nonlinear robot actuation, which was validated with laser path–following tests. Submillimeter laser steering accuracy was demonstrated with a mean error < 0.20 mm. MRI compatibility testing demonstrated zero observable image artifacts during robot operation. Ex vivo tissue ablation and a cadaveric head-and-neck trial were carried out under MRI, where we employed MR thermometry to monitor the tissue ablation margin and thermal diffusion intraoperatively.

State of the Art and Future Opportunities in MRI-Guided Robot-Assisted Surgery and Interventions

“…Such operations also benefit from MRI during the ablation with the real-time thermal distribution of the 3-D resection margin evaluated. Fang et al [75] proposed an MRI-guided soft robotic manipulator for MRI-guided transoral laser microsurgery. To comply with and pass through the constrained oral cavity, the robot was designed in miniature size (Ø12 × 100 mm) with two segments (i.e., an active bending segment for coarse robot navigation and a fine distal laser manipulator).…”

“…Achieving real-time and precise position tracking of interventional robots and patient anatomy plays a significant role in MRI-guided intervention and diagnosis. Because of this, the position feedback could realize closedloop control of surgical robots thus improving the clinical outcomes [75]. Coil-based tracking is one promising method that has been widely studied and employed in MRI-guided interventional applications.…”

The Forefront of Dentistry—Promising Tech-Innovations and New Treatments

“…Robot technology has been demonstrated in many fields of dentistry, for example, in implantology, restorative dentistry, and education (Fang et al 2021;van Riet et al 2021avan Riet et al , 2021b. Some robotic solutions have become commercially available in recent years, such as the robot "Yomi" (Neocis) for implant placement, especially in edentulous patients, and have received 510(k) clearance from the FDA.…”

Light in the Larynx: a Miniaturized Robotic Optical Fiber for In-office Laser Surgery of the Vocal Folds

“…Several other groups are actively developing robots for laryngeal laser surgery [10]- [15], but none of the existing prototypes can be readily used in the office procedures we consider in this study. In the following, we briefly describe the surgical setup and workflow of an office procedure.…”