Segmented MRI Catheters Preventing Wire Resonance
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Solution Overview
Problem
Conventional MRI catheters and guidewires with metallic elements face heating issues due to interactions with MRI fields, leading to potential damage and patient injury from excessive heat generation.
Innovation Solution
Segmented MRI-compatible interventional devices featuring braided or non-braided helical wires with insulated breaks, arranged in a tubular configuration to avoid resonance and heat generation, providing mechanical properties like torque control and flexibility while minimizing weak areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional metallic braided catheters are used to provide mechanical properties, then torque control and flexibility are improved, but heating and resonance occur during MRI procedures
Solution Approach 1:
The continuous metallic wires are divided into multiple insulated wire segments along the longitudinal axis of the catheter. Each segment is electrically isolated from adjacent segments by insulating material, preventing formation of continuous conductive loops that would generate strong electrical currents and resonance during MRI procedures while maintaining mechanical structural integrity
Solution Approach 2:
An insulating material is introduced between adjacent wire segments to electrically isolate them. This intermediary layer prevents direct electrical contact between segments, blocking the formation of continuous conductive paths that would otherwise interact with MRI fields to generate harmful heat and resonance
2Object-affected harmful factors
If wire segments are insulated and separated to avoid heating, then safety during MRI is improved, but mechanical strength may be compromised
Solution Approach 1:
The catheter structure is segmented into multiple insulated wire segments that maintain mechanical continuity through their braided configuration. The segmentation electrically isolates segments to prevent heating while the braided arrangement of multiple segments preserves the overall mechanical strength and structural integrity of the catheter
Solution Approach 2:
The catheter employs a composite structure combining conductive wire segments with insulating material. This composite design allows the conductive segments to provide necessary mechanical properties while the insulating material prevents harmful electromagnetic interactions, achieving both mechanical strength and MRI safety
3Reliability
If breaks are staggered to minimize weak areas, then structural reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The breaks in adjacent wire segments are positioned asymmetrically along the longitudinal axis, creating a staggered pattern rather than aligned breaks. This asymmetric arrangement distributes stress more evenly and minimizes weak areas where breaks are aligned, improving structural reliability while the regular repeating pattern maintains manufacturing feasibility
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The segmented design prevents substantial heating during MRI procedures, ensuring the safety and effectiveness of the devices by maintaining mechanical integrity without generating excessive heat.
Implementation Method 1
conventional catheters typically include a woven metallic braid of wires incorporated into a polymeric extrusion to impart these mechanical properties. However, such a woven metallic braid of wires can undesirably interact with MRI to generate strong electrical currents or resonance in the wires, which can produce excess heat
Data Source
AI summary
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.