MRI Compatible Stimulation Leads with RF Chokes
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Solution Overview
Problem
Current medical lead systems for Deep Brain Stimulation (DBS) and other electro-stimulation therapies are not MRI compatible, leading to image distortion, unwanted RF current induction, and inaccurate electrode placement, which can result in suboptimal clinical outcomes.
Innovation Solution
Development of MRI compatible multi-purpose lead systems with RF chokes and induced current resistant designs, incorporating an integrated MRI receive antenna and stimulating electrodes, allowing for precise placement and operation during MRI procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional DBS leads with ferromagnetic materials are used, then the leads can provide effective electrical stimulation, but the leads cause image distortion and are incompatible with MRI imaging
Solution Approach 1:
The patent changes the material parameters of the lead by using non-ferromagnetic materials (such as titanium, stainless steel 316L, or nickel-titanium alloys) instead of traditional ferromagnetic materials. This parameter change allows the lead to be MRI compatible while maintaining its electrical stimulation functionality, resolving the contradiction between reliability and MRI compatibility
Solution Approach 2:
The patent employs composite material structures where the lead incorporates non-ferromagnetic materials combined with specialized coatings and insulation layers. This composite approach maintains the electrical conductivity and mechanical strength needed for reliable stimulation while eliminating ferromagnetic properties that cause image distortion and safety issues during MRI
2Ease of operation
If traditional leads are used in MRI environment, then the leads can function for stimulation, but the leads are susceptible to unwanted induced RF currents and localized heating
Solution Approach 1:
The patent converts the potentially harmful RF current induction into a beneficial feature by designing the lead with an integrated MRI receive antenna. The same conductive elements that could act as unintended antennas are deliberately configured as functional antenna elements, allowing the lead to actively receive MRI signals while maintaining stimulation capability. This resolves the contradiction by transforming the harmful RF susceptibility into a useful dual-function capability
Solution Approach 2:
The patent introduces RF filtering circuits and impedance matching networks as intermediary components between the lead electrodes and the MRI environment. These intermediary elements selectively block harmful induced RF currents while allowing the desired stimulation signals to pass through, and simultaneously enable the antenna function for MRI signal reception, thus resolving the contradiction between stimulation operation and RF safety
3Reliability
If DBS electrodes are placed in neural tissue, then therapeutic stimulation can be provided, but inaccurate placement reduces clinical efficacy in about 30% of patients
Solution Approach 1:
The patent implements real-time feedback by integrating an MRI receive antenna directly into the lead, enabling intraoperative MRI imaging to monitor electrode placement accuracy. The MRI system provides continuous feedback on the precise location of the electrodes relative to the target neural structures, allowing the surgeon to adjust placement before final implantation. This feedback mechanism eliminates the 30% failure rate associated with inaccurate placement by ensuring precise positioning through real-time imaging guidance
4Object-affected harmful factors
If the lead system is designed for MRI compatibility, then safe operation during MRI is achieved, but the lead structure becomes more complex with integrated antennas and RF chokes
Solution Approach 1:
The patent applies multi-functionality by designing the lead where the same conductive elements serve multiple purposes: they function as both stimulation electrodes and as an integrated MRI receive antenna. The lead structure is configured so that the electrode conductors themselves form the antenna elements, eliminating the need for separate antenna components. This universal design achieves MRI safety and compatibility while minimizing structural complexity by making the lead itself multi-functional rather than adding separate specialized components
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 MRI compatible lead systems enable accurate electrode placement and safe operation during MRI, reducing the risk of RF induced currents and improving clinical efficacy by integrating RF chokes and an MRI antenna for precise positioning and stimulation.
Implementation Method 1
a plurality of axially spaced apart RF chokes disposed on and/or in an axially extending shielding layer of the lead in advance of the at least one electrode to inhibit induced RF current from forming and/or traveling along the shielding layer
Implementation Method 2
The lead systems may be implantable, MRI compatible multi-purpose lead systems configured to provide an internal MRI receive antenna
Data Source
AI summary
In vivo medical stimulation probes include an elongate lead having at least one stimulation electrode disposed on a distal portion thereof. The probes may include a plurality of axially spaced apart RF chokes disposed on and/or in an axially extending shielding layer of the lead in advance of the at least one electrode to inhibit induced RF current from forming and/or traveling along the shielding layer.