An MRI Actuated and Imaged Concentric Tube Catheter

Two major challenges associated with robotic catheterization are, (a) the provision of controllable degrees of freedom (DoFs) and, (b) accessing feedback on the shape and pose of the catheter, safely and at a useful diameter-scale. Miniaturizable active steering can be provided via magnetic actuation and MRI offers high definition, radiation free, 3D images which can be leveraged as a shape sensor. For the higher controllable DoFs required for shape forming these two solutions are currently incompatible. Here, we propose a structurally adaptable “Coaxial Sleeve Magnetic Actuator” (CoSMA), driven by the background field of the MRI scanner. This enables multi-DoF motion and real-time feedback, both via the MRI system. Our approach combines the magnetic actuation principle of the easy axis of alignment with the mechanical principles of concentric tube designs. This concept allows for a materially flexible (E~1MPa), and therefore risk reduced, multi-DoF catheter. Low magnetic volume required for actuation minimizes imaging artifacts caused by magnetic elements permitting a view of both the CoSMA and the surrounding anatomy. We demonstrate the CoSMA, constructed of three coaxial components, two sleeves and one guidewire, with respective outer diameters of 3 mm, 1.5 mm and 0.4 mm, in an aortic arch phantom navigation within the bore of a pre-clinical MRI scanner.