Introduction Acute ischemic stroke can be treated effectively under X-ray guidance, but eligibility for such treatment is limited by small time windows following symptom onset. Treatment windows could be extended with MRI information since diffusion weighted imaging and perfusion imaging are the gold standard in determining if brain tissue is still salvageable by reperfusion therapy. Lack of safe tooling in such unique environments has limited catheter-based interventions as commercial devices use metallic reinforcement, introducing risk of RF-induced heating. We present a polymer-based catheter with a passive ink-based marker to create low-profile, MR-visible markers that can also be visualized under X-ray. Prototype feasibility was demonstrated in vitro and mechanically compared to a commercial guide catheter.
Methods Prototypes were built in a catheter fabrication facility (Penumbra, Inc., Alameda, CA). Polymer-based filament was wound onto an inner plastic liner. Four circumferential passive marker bands were painted 2 cm from the distal tip. Markers were an epoxy-based radiopaque ink (Creative Materials, Ayer, MA) doped with iron(III) oxide (Fe2O3) nanoparticles of 20–40 nm diameter (Alfa Aesar, Tewksbury, MA). The resulting subassembly was laminated with a multi-durometer thermoplastic jacket. MRI experiments were performed in a clinical hybrid interventional XMR suite. The catheter was submerged in water oriented parallel to B0 on a 1.5T MRI scanner (Achieva, Philips, Best, The Netherlands). A gradient echo (GRE) and fast spin echo (TSE) were acquired. X-ray images were captured using a Cios Alpha portable C-arm (Siemens Healthineers, AG, Forccheim, Germany). Kink resistance was quantified with a benchtop fixture against a commercial guide catheter of similar dimensions.
Results The final device had outer and inner diameters of 2.36 mm and 1.83 mm, respectively, and a wall thickness of 0.265 mm. Negative contrast signal caused by the markers showed good tracking characteristics in the GRE and TSE sequences (figure 1). Radiopaque markers were visualized under X-ray in the water phantom. Prototype and commercial catheter distal kink radii were 7.5 mm and 11.0 mm, respectively. The prototype exhibited a larger wall thickness than the commercial device.
Conclusions MR and X-ray images demonstrated that the passive markers possessed good negative contrast signal at 1.5T and radiopacity in a water-filled phantom. Improved kink radii compared to a commercial catheter demonstrated a device that could maintain lumen patency during navigation. Device construction featured simple manufacturing steps to produce a low-profile catheter with MRI and X-ray visibility for neuro-interventional applications.
Disclosures B. Kilbride: 6; C; Penumbra, Inc. C. Jordan: 6; C; Penumbra, Inc. A. Chu: None. D. Barry: None. T. Moore: None. A. Martin: None. M. Wilson: None. S. Hetts: None.
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