Inductive Windings in Pulse Generator Headers for MRI Safety
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Solution Overview
Problem
Neurostimulation systems are incompatible with MRI due to MRI-induced current causing significant tissue heating, particularly due to the presence of metal components leading to 'eddy current' and 'antenna effect', which results in potential tissue damage.
Innovation Solution
A pulse generator with a hermetically sealed housing and a header containing inductive windings around connectors to limit MRI-induced currents, providing an impedance that suppresses heating by electrically connecting the windings between connector structures and feedthrough wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal components are used in neurostimulation systems, then structural strength and hermetic sealing are improved, but MRI-induced current heating is worsened
Solution Approach 1:
An insulative coating layer is applied to the metal components (header, connectors, feedthrough wires) to act as an intermediary barrier. This coating prevents direct interaction between the metal and the MRI RF field, blocking the induction of eddy currents while preserving the structural integrity and hermetic sealing properties of the metal components.
2Ease of manufacture
If conventional connector structures are used in pulse generators, then ease of manufacture is improved, but MRI compatibility is worsened
Solution Approach 1:
The connector structure is transformed into a composite material system by combining metal components with an insulative coating layer. The metal provides structural strength and electrical conductivity where needed, while the insulative coating suppresses MRI-induced current heating, creating a composite structure that addresses both manufacturing ease and MRI compatibility.
3Reliability
If hermetically sealed metallic housing is used, then reliability is improved, but MRI-induced eddy current heating is worsened
Solution Approach 1:
The hermetically sealed metallic housing is coated with an insulative material that acts as an intermediary layer. This coating maintains the hermetic sealing function by conforming to the metal housing surface while preventing the induction of eddy currents during MRI procedures, thus preserving reliability while eliminating the harmful heating effect.
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 inductive windings effectively mitigate MRI-induced heating by creating an impedance that limits current flow, reducing tissue damage and ensuring compatibility of neurostimulation systems with MRI environments.
Implementation Method 1
inductive winding is disposed around or adjacent to each of the connector structures and is electrically connected between the respective connector structure and a corresponding feedthrough wire to limit MRI induced heating
Implementation Method 2
the time-varying magnetic RF field induces current within the tissue of a patient that flows in closed-paths. When conventional pulse generator 103 and conventional implantable lead 104 are placed within tissue in which eddy currents are present
Implementation Method 3
providing an impedance that suppresses heating by electrically connecting the windings between connector structures and feedthrough wires
Data Source
AI summary
In one embodiment, a pulse generator for generating electrical stimulation for delivery to a patient, comprises: a hermetically sealed housing containing pulse generating circuitry; a header coupled to the housing for receiving one or more stimulation leads, wherein feedthrough wires are provided to conduct electrical pulses from the pulse generating circuitry to the header; the header comprising a plurality of connectors for electrically connecting to each terminal of the one or more stimulation leads, wherein an inductive winding is disposed around or adjacent to each of the connector structures and is electrically connected between the respective connector structure and a corresponding feedthrough wire to limit MRI induced heating of a respective electrode of the one or more stimulation leads.