Segmented MRI Lead Wire with Fluid Coupling

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Solution Overview

Problem

Conventional implanted medical devices (IMDs) are incompatible with magnetic resonance (MR) imaging due to RF heating issues, causing patient discomfort and limiting imaging options to less desirable methods like CT or X-ray, which have inferior image resolution.

Innovation Solution

A lead wire assembly for IMDs with conductive segments and a fluid-filled cavity that electrically couples adjacent segments, attenuating induced RF signals from MR systems, and designed with segment lengths less than one-half wavelength of MR system RF signals to prevent standing waves and heating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional IMD lead wires are used during MR imaging, then the lead wire can transmit driving signals, but the lead wire acts as an antenna to RF emissions causing RF heating and tissue burning

Engineering Contradiction:

Improvesignal transmission capabilityVSAvoidRF heating and tissue burning

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The lead wire is divided into multiple discrete conductive segments separated by non-conductive barriers. This segmentation prevents the formation of continuous standing waves along the lead wire, thereby eliminating the antenna effect that causes RF heating during MR imaging while maintaining signal transmission capability through the segmented structure

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Non-conductive barriers are introduced as intermediary elements between adjacent conductive segments. These barriers electrically isolate the segments from each other, preventing RF signal continuity that would create standing waves, while still allowing the lead to function as an electrical conduit for driving signals through the segmented path

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the lead wire length is greater than one-half wavelength of RF signals, then the lead can maintain effective signal transmission, but it supports standing wave formation and RF heating

Engineering Contradiction:

Improvesignal transmission effectivenessVSAvoidlead wire temperature due to RF heating

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The lead wire structure is segmented into multiple conductive sections separated by non-conductive barriers. This segmentation disrupts the formation of standing waves even when the overall lead length exceeds one-half wavelength of RF signals, preventing RF heating while preserving signal transmission effectiveness through the segmented conductive path

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If conventional IMDs are implanted, then patients can receive treatment, but they cannot be safely scanned using MR methods and must use CT or X-ray which emit ionizing radiation and have inferior image resolution

Engineering Contradiction:

Improveimaging modality optionsVSAvoidionizing radiation exposure and inferior image resolution

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The invention converts the potentially harmful interaction between lead wires and RF fields into a beneficial outcome by using segmented conductors with non-conductive barriers. This design allows patients with implanted devices to safely undergo MR imaging, eliminating the need for alternative imaging methods that use ionizing radiation or provide inferior soft tissue resolution

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

Enables safe MR imaging of patients with implanted devices by reducing RF-induced heating and maintaining effective signal transmission, overcoming the limitations of conventional IMDs in MR environments.

Implementation Method 1

The fluid electrically couples adjacent conductive segments to pass driving signals of the implantable medical device

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

The fluid may further attenuate induced signals generated by radiofrequency (RF) signals of a magnetic resonance (MR) system

Methodology Applied

Scientific EffectRF signal attenuation: Absorption (EM radiation)

Implementation Method 3

A length of at least one of the plurality of conductive segments may be less than one-half wavelength length of the radiofrequency (RF) signals generated by the MR system

Methodology Applied

Scientific EffectStanding wave prevention: Resonance

Data Source

PatentUS11052242B1MRI compatible lead

Publication Date: 2021.07.06 AVERY BIOMEDICAL DEVICES

AI summary

A lead wire assembly apparatus for an implantable medical device (IMD), the apparatus including a lead having first and second ends and a plurality of separate conductive segments serially located therebetween; a cover defining at least one cavity situated about ends of adjacent conductive segments; and a fluid located in the at least one cavity and coupling the adjacent conductive segments to each other. The fluid electrically couples adjacent conductive segments to pass driving signals of the implantable medical device. The fluid may further attenuate induced signals generated by radiofrequency (RF) signals of a magnetic resonance (MR) system.