Segmented MRI catheters and other interventional devices
Inventors
Lederman, Robert J. • Kocaturk, Ozgur
Assignees
US Department of Health and Human Services
Publication Number
US-10835710-B2
Publication Date
2020-11-17
Expiration Date
2036-09-14
Interested in licensing this patent?
MTEC can help explore whether this patent might be available for licensing for your application.
Abstract
Disclosed herein are segmented MRI-compatible interventional devices, such as catheters and guidewires, that provide desired mechanical properties while avoiding undesired interactions with MRI fields. Disclosed devices can include helical wires with insulated breaks at intervals along each wire so that the insulated wire segments are individually short enough to avoid substantial resonance and heat being generated in the wires due to an applied MRI field. The segmented wires can be organized into a braided/woven tubular configuration or a non-braided intercalated/parallel tubular configuration that provides the desired mechanical properties similar to conventional metallic braided catheters. The helical wire segments can be insulated such that the wires do not touch each other at points where they cross over each other. Breaks in the wires can be staggered along the longitudinal axis of the device and/or circumferentially around the device to minimize formation of weak areas where wire breaks are aligned or grouped.
Core Innovation
The invention relates to segmented MRI-compatible interventional devices such as catheters and guidewires that provide desired mechanical properties while avoiding undesired interactions with MRI fields. These devices include helical wires with insulated breaks at intervals, segmenting each wire into individually short lengths to avoid substantial resonance and heat generation during MRI exposure. The wire segments are arranged in tubular configurations, either braided/woven or non-braided intercalated/parallel tubular configurations, to provide mechanical properties similar to conventional metallic braided catheters.
The disclosed segmented wires are insulated so that they do not touch each other at crossover points, and breaks in the wires are staggered both longitudinally and circumferentially to minimize formation of weak areas that would result from aligned wire breaks. The wires can have differing helicities or chiralities to form braids, or they can all have the same helicity to form parallel, intercalated wires that do not cross over each other, enabling thinner catheter walls.
The problem being solved is the risk of heating and resonance that occurs in conventional metallic braided catheters when used during MRI catheterization. Metallic braid elements interact undesirably with MRI fields, generating strong electrical currents or resonance that produce excess heat, potentially damaging the catheter and harming the patient. The invention addresses this problem by segmenting the wires into electrically insulated short sections to prevent resonance and heat while retaining mechanical functionality.
Claims Coverage
The patent includes one independent apparatus claim and one independent method claim. These claims cover an elongated MRI-compatible interventional device configured to avoid heating during MRI, and a method of using such a device.
Segmentation of helical wires with insulating breaks
The interventional device comprises multiple helical wires arranged in a tubular or rod-shaped configuration, each wire segmented by non-electrically-conductive breaks such that each segment's length is less than a threshold length to prevent substantial resonance and heating during MRI exposure. Each segment is electrically insulated from other segments.
Threshold length selection based on MRI field strength
The length of each wire segment is selected based on the MRI field strength for the intended application to ensure safety and avoid resonance, with threshold lengths being less than an associated resonant length or equal to or less than ¼ of the Larmor frequency wavelength in vivo.
Electrical insulation and arrangement of wire segments
Wire segments do not touch each other at ends, sides, or crossover points due to electrical insulation. Breaks are staggered along axial and circumferential directions to minimize weak areas. Breaks may be arranged in groups of two in wires of the same helicity or separated individually for enhanced mechanical properties.
Wire arrangement and braid patterns
The wires can be arranged in braided patterns with portions having opposite helical chiralities, or arranged in parallel, non-overlapping intercalated configurations all having the same chirality, enabling thinner catheter walls. Braids can have diamond, full load, half load patterns with various numbers of wires.
Material and structural features
Each wire is covered individually in insulating material, and the wire braid is encased in tubular insulating material. Wire cross-sections may vary in shape and size. Wire breaks can be formed using methods such as laser ablation and can be incorporated before or after braid formation.
MRI compatibility and use indications
The device includes provisions for MRI safety by selecting wire segment lengths to avoid heating and may optionally include MRI conspicuity markers or resonant coils for enhanced imaging visibility.
Method for using the segmented device in MRI
A method claim covers providing the segmented interventional device and using it in an MRI field application without causing substantial heating or resonance induced by the MRI field.
The claims collectively cover an MRI-compatible interventional device composed of segmented, insulated helical wires arranged to avoid resonance and heating during MRI, with specific structural and insulation arrangements, and a method of using such devices safely in MRI environments.
Stated Advantages
Provides desired mechanical properties similar to conventional metallic braided catheters such as torque control, flexibility, resistance to kinking, and column strength.
Avoids substantial heating and resonance in metallic components during MRI, reducing patient risk and device damage.
Allowance for various catheter sizes and wire configurations with maintained MRI safety.
Enables catheter designs with reduced wall thickness by using parallel, non-overlapping wire arrangements.
Documented Applications
MRI-guided catheterization procedures using segmented MRI-compatible catheters that reduce the risk of heating during diagnostic or therapeutic interventions.
Guidewires and other elongated transvascular or transluminal interventional devices for safe use in MRI environments.
Interested in licensing this patent?