A team led by Professor Sylvain Martel at the Polytechnique Montréal Nanorobotics Laboratory has developed a novel approach to tackling one of the biggest challenges of endovascular surgery: how to reach the most difficult-to-access physiological locations. Their solution is a robotic platform that uses the fringe field generated by the superconducting magnet of a clinical magnetic resonance imaging (MRI) scanner to guide medical instruments through deeper and more complex vascular structures. The approach has been successfully demonstrated in-vivo, and is the subject of an article just published in Science Robotics. #surgery #MRI #vivonovel #approach #endovascular
When a researcher "thinks outside the box"--literally
Imagine having to push a wire as thin as a human hair deeper and deeper inside a very long, very narrow tube full of twists and turns. The wire's lack of rigidity, along with the friction forces exerted on the walls of the tube, will eventually render the manoeuvre impossible, with the wire ending up folded on itself and stuck in a turn of the tube. This is exactly the challenge facing surgeons who seek to perform minimally invasive procedures in ever-deeper parts of the human body by steering a guidewire or other instrumentation (such as a catheter) through narrow, tortuous networks of blood vessels.
It is possible, however, to harness a directional pulling force to complement the pushing force, countering the friction forces inside the blood vessel and moving the instrument much farther. The tip of the device is magnetized, and pulled along inside the vessels by the attraction force of another magnet. Only a powerful superconducting magnet outside the patient's body can provide the extra attraction needed to steer the magnetized device as far as possible. There is one piece of modern hospital equipment that can play that role: an MRI scanner, which has a superconducting magnet that generates a field tens of thousands of times stronger than that of the Earth.
The magnetic field inside the tunnel of an MRI scanner, however, is uniform; this is key to how patient imaging is performed. That uniformity poses a problem: to pull the tip of the instrument through the labyrinthine vascular structures, the guiding magnetic field must be modulated to the greatest possible amplitude and then be decreased as quickly as possible.
Pondering that problem, Professor Martel had the idea of using not the main magnetic field present inside the MRI machine tunnel, but the so-called fringe field outside the machine.
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