Researchers at the Polytechnique Montréal Nanorobotics Laboratory in Canada have developed a new method to guide endovascular instruments into complex vascular structures that were hitherto inaccessible to endovascular surgeons. The technique involves moving the patient and the endovascular instrument using a robotic platform within a magnetic field.
Endovascular surgery has enabled minimally invasive approaches for a huge array of surgical interventions. However, the technique is not without its challenges, and advancing a thin catheter through long and tortuous vasculature can be difficult, with the device potentially getting stuck. In fact, certain areas of the body are inaccessible to endovascular surgeons because of the complexity of their vasculature and the impossibility of advancing a catheter through it using conventional means.
To address this, these researchers conceived of an external force that could help to pull a catheter through the vasculature, complementing efforts to push the catheter, and making it easier to advance it into currently inaccessible areas. Their technique involves an external magnetic field that acts on a magnetic catheter tip and a robotic platform to move the patient in relation to the magnetic field. An MRI scanner provides the magnetic field, although the fringe field outside the MRI machine is used rather than the uniform field inside.
“Manufacturers of MRI scanners will normally reduce the fringe field to the minimum,” said Professor Sylvain Martel, a researcher involved in the study. “The result is a very high-amplitude field that decays very rapidly. For us, that fringe field represents an excellent solution that is far superior to the best existing magnetic guidance approaches, and it is in a peripheral space conducive to human-scale interventions. To the best of our knowledge, this is the first time that an MRI fringe field has been used for a medical application.”
To orient the magnetic field to correctly aid in moving the magnetic catheter tip through the vasculature, the research team realized that it would be easier to move the patient rather than a heavy MRI scanner. To achieve this, the researchers used a robotic table placed within the fringe magnetic field of the scanner, on which the patient rests and can be moved around. The table moves automatically to optimally place the patient so as to allow the catheter to move toward its target.
The new technique should help broaden what’s possible in minimally invasive surgery, and hopefully make it even safer.
Study in Science Robotics: Using the fringe field of a clinical MRI scanner enables robotic navigation of tethered instruments in deeper vascular regions