Fringe Field Navigation for Catheterization

摘要

To navigate smaller magnetic guidewires and catheters deeper through narrower blood vessels, a very large directional magnetic gradient field is required. As such, superconducting magnets such as the ones used in clinical MRI scanners are known to far exceed resistive coils or permanent magnets for generating such high field. But because superconducting magnets are not appropriate for switching or modulating fields such as for the generation of 3D directional gradient forces, a new approach capable of very high directional gradient forces from such superconducting magnets and referred to here as Fringe Field Navigation (FFN) is introduced. To provide such high directional gradients with a relatively high magnetic field strength in the interventional space, FFN uses the external field known as the fringe field of the MRI scanner. Since such large magnet capable of generating a much higher but constant field cannot practically be moved, superior directional gradients are achieved by robotically positioning and moving the patient outside and in proximity of the scanner accordingly. Preliminary results with a 1.5 T clinical scanner indicate the possibility to perform whole body FFN using 6-DOF gradients of 2000-4000mT/m which is much larger than the 300mT/m achievable with existing magnetic catheter navigation platforms.