Magnetic flexible endoscope: a novel platform for diagnostic and therapeutic colonoscopy

摘要

Colonoscopy is widely performed for direct visualization and therapeutic intervention in the colon. Although colonoscopy is a relatively safe procedure, there are several limitations because of the unintuitive drive mechanism and mechanical design of current conventional colonoscopes (CCs). These include sedation-related events, patient discomfort because of looping, perforation and colonic trauma, long learning curve and training time, variable quality, and endoscopist injury because of poor ergonomics. To overcome these limitations, endoscopy as currently practiced would require a dramatic transformation in both endoscope design and technique used for actuation. The magnetic flexible endoscope (MFE) was developed to address these limitations as a highly flexible, single-use, robot-assisted, magnetically manipulated endoscope. The MFE is composed of a handheld controller (thumb-operated 4-directional joystick with hydraulic controls for insufflation, irrigation, camera cleaning, and suction and a depressible button for forward motion control added to the chassis), a robot manipulator (Kuka, LBR Med-14 R820, Augsburg, Germany; commercially available and certified for use in clinical settings International Electrotechnical Commission [IEC] 60601-1, IEC 60601-2, and IEC 62304) with a magnetic end effector, and a magnetic flexible endoscope to maintain the functionality of a CC (Fig. 1). The robotic arm is unlike the CC, which is pushed for advancement; the MFE is driven by magnetic coupling to enable a “front-pull” actuation mechanism (Fig. 2). The forward-drive mechanism prevents buckling of the insertion tube, looping, and colonic wall stress, reducing the risk of perforation and pain during the procedure. The positioning of the robotic arm is the result of a complex 3-dimensional model of the magnetic fields generated by the 2 magnets and their interaction. A patented algorithm allows for the localization of the endoscope and consequently computes the desired robot motion. Therefore, the robotic arm does not need to be positioned directly in line with the desired direction to move the endoscope tip, making it possible to move the tip in all directions by moving and rotating the arm around the patient. Although the arm is generally above the patient, it is possible to tilt the endoscope tip away from the magnet if needed, by taking advantage of the magnetic repulsion. To avoid constant pulling of the magnets with respect to one another, the magnets are in a relative configuration such that the external magnet north pole is directed toward the endoscope tip, whereas the internal magnet is orientated in the opposite direction. With this arrangement, rotations on the external magnet cause opposite rotations on the endoscope tip, and therefore the endoscope is stabilized by active control of the magnetic link with the robotic arm. With the integration of robotic assistance and autonomous function, the challenging task of endoscope navigation becomes simplified. In vivo validation of colonic navigation for diagnostic and therapeutic colonoscopy is now tested. The MFE was tested in vivo using two 37-kg female, Danish Duroc, large white-Landrace cross-swine to evaluate system safety, core functionality, navigation, and capacity for therapeutic intervention. The primary outcome measure was safety (trauma or premature demise). The MFE was navigated through the colon and withdrawn 5 times. Autonomous navigation and endoscopic maneuvers, retroflexion, biopsy sampling, and EMR were performed (Fig. 3). The MFE successfully and safely navigated the swine colon with good visibility and without gross colonic trauma. Autonomous navigation of the MFE was successful at autonomously detecting the lumen center and orienting the endoscope for biopsy sampling (Figs. 4 and 5). The detection algorithm tracked the target location, whereas the motion control software aligned the endoscope tip with the biopsy forceps for tissue acquisition (Fig. 6). Duri