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Magnetically‐assisted remote control (MARC) steering of endovascular catheters for interventional MRI: A model for deflection and design implications
Author(s) -
Settecase Fabio,
Sussman Marshall S.,
Wilson Mark W.,
Hetts Steven,
Arenson Ronald L.,
Malba Vincent,
Bernhardt Anthony F.,
Kucharczyk Walter,
Roberts Timothy P. L.
Publication year - 2007
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.2750963
Subject(s) - deflection (physics) , catheter , scanner , imaging phantom , magnetic resonance imaging , biomedical engineering , moment of inertia , materials science , physics , surgery , radiology , optics , medicine , classical mechanics
Current applied to wire coils wound at the tip of an endovascular catheter can be used to remotely steer a catheter under magnetic resonance imaging guidance. In this study, we derive and validate an equation that characterizes the relationship between deflection and a number of physical factors: θ ∕ sin ( γ − θ ) = n I A B L ∕ E I A , where θ is the deflection angle, n is the number of solenoidal turns, I is the current, A is the cross‐sectional area of the catheter tip, B is the magnetic resonance (MR) scanner main magnetic field, L is the unconstrained catheter length, E is Young's Modulus for the catheter material, andI Ais the area moment of inertia, and γ is the initial angle between the catheter tip and B . Solenoids of 50, 100, or 150 turns were wound on 1.8 F and 5 F catheters. Varying currents were applied remotely using a DC power supply in the MRI control room. The distal catheter tip was suspended within a phantom at varying lengths. Images were obtained with a 1.5 T or a 3 T MR scanner using “real‐time” MR pulse sequences. Deflection angles were measured on acquired images. Catheter bending stiffess was determined using a tensile testing apparatus and a stereomicroscope. Predicted relationships between deflection and various physical factors were observed ( R 2 = 0.98 − 0.99 ) . The derived equation provides a framework for modeling of the behavior of the specialized catheter tip. Each physical factor studied has implications for catheter design and device implementation.