MRI-compatible and sensorless haptic feedback for cable-driven medical robotics to perform teleoperated needle-based interventions.

PURPOSE: Surgical robotics have demonstrated their significance in assisting physicians during minimally invasive surgery. Especially, the integration of haptic and tactile feedback technologies can enhance the surgeon's performance and overall patient outcomes. However, the current state-of-the-art lacks such interaction feedback opportunities, especially in robotic-assisted interventional magnetic resonance imaging (iMRI), which is gaining importance in clinical practice, specifically for percutaneous needle punctures. METHODS: The cable-driven 'Micropositioning Robotics for Image-Guided Surgery' (µRIGS) system utilized the back-electromotive force effect of the stepper motor load to measure cable tensile forces without external sensors, employing the TMC5160 motor driver. The aim was to generate a sensorless haptic feedback (SHF) for remote needle advancement, incorporating collision detection and homing capabilities for internal automation processes. Three different phantoms capable of mimicking soft tissue were used to evaluate the difference in force feedback between manual needle puncture and the SHF, both technically and in terms of user experience. RESULTS: The SHF achieved a sampling rate of 800 Hz and a mean force resolution of 0.26 ± 0.22 N, primarily dependent on motor current and rotation speed, with a mean maximum force of 15 N. In most cases, the SHF data aligned with the intended phantom-related force progression. The evaluation of the user study demonstrated no significant differences between the SHF technology and manual puncturing. CONCLUSION: The presented SHF of the µRIGS system introduced a novel MR-compatible technique to bridge the gap between medical robotics and interaction during real-time needle-based interventions.

Feasibility Study of a novel MRI-safe and interactive respiratory biofeedback system.

This paper presents a feasibility study of a novel MRI-safe and interactive respiratory biofeedback system. Breathing-induced organ motion is a huge problem in medical imaging as well as in radiation therapy. Controlled breathing is an essential requirement for the efficiency of a successful diagnosis and therapy. To address this problem, a new interactive feedback system was developed. A commando unit provides instructions regarding the desired respiration pattern for the proband and a feedback unit gives a response about the deviation between the actual and the desired respiratory motion. A first feasibility study confirmed the viability of the new system. By means of the interactive biofeedback system, the test persons were able to adjust their respiration according to a prescribed breathing pattern. Our results showed that an interactive respiratory biofeedback system is able to reduce breathing motion and with that could be very beneficial for MR-imaging and also for radiation therapy procedures.

In-room ultrasound fusion combined with fully compatible 3D-printed holding arm - rethinking interventional MRI.

There is no real need to discuss the potential advantages - mainly the excellent soft tissue contrast, nonionizing radiation, flow, and molecular information - of magnetic resonance imaging (MRI) as an intraoperative diagnosis and therapy system particularly for neurological applications and oncological therapies. Difficult patient access in conventional horizontal-field superconductive magnets, very high investment and operational expenses, and the need for special nonferromagnetic therapy tools have however prevented the widespread use of MRI as imaging and guidance tool for therapy purposes. The interventional use of MRI systems follows for the last 20+ years the strategy to use standard diagnostic systems and add more or less complicated and expensive components (eg, MRI-compatible robotic systems, specially shielded in-room monitors, dedicated tools and devices made from low-susceptibility materials, etc) to overcome the difficulties in the therapy process. We are proposing to rethink that approach using an in-room portable ultrasound (US) system that can be safely operated till 1 m away from the opening of a 3T imaging system. The live US images can be tracked using an optical inside-out approach adding a camera to the US probe in combination with optical reference markers to allow direct fusion with the MRI images inside the MRI suite. This leads to a comfortable US-guided intervention and excellent patient access directly on the MRI patient bed. This was combined with an entirely mechanical MRI-compatible 7 degrees of freedom holding arm concept, which shows that this test environment is a different way to create a cost-efficient and effective setup that combines the advantages of MRI and US by largely avoiding the drawbacks of current interventional MRI concepts.