Implantable Device RF Heating Management via Induced Voltage
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Solution Overview
Problem
Implantable medical devices (IMDs) face heating issues during magnetic resonance imaging (MRI) scans due to RF excitation, leading to potential tissue damage and limitations on MRI scan power and duration, as existing methods lack accurate temperature monitoring and effective heating prediction.
Innovation Solution
An IMD system that detects induced voltage in electrodes or conductive leads caused by the MRI's RF field, using this voltage as a marker to predict and manage heating, adjusting MRI scan settings in real-time to maintain safe temperatures, including identifying optimal shimming settings and modifying scan parameters to prevent excessive heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If MRI scan power and duration are increased to improve imaging quality and reduce scan time, then productivity and imaging quality improve, but heating of the IMD and surrounding tissue increases causing safety risks
Solution Approach 1:
The system continuously monitors the induced voltage in the IMD during the MRI scan and uses this feedback to dynamically adjust scan parameters. The MRI system receives real-time voltage information from the IMD and modifies subsequent RF pulse sequences to maintain induced voltage within safe thresholds, enabling extended scans at higher power levels without excessive heating
Solution Approach 2:
The MRI scan parameters are made dynamic rather than static. The system adjusts RF pulse power, duration, and sequence timing in real-time based on the monitored induced voltage levels. This allows the scan to operate at optimal power levels throughout, increasing overall productivity while preventing dangerous temperature rises
2Reliability
If restrictive MRI labeling and conservative scan protocols are applied to ensure safety, then reliability improves, but productivity and imaging quality deteriorate due to limited scan power and duration
Solution Approach 1:
The IMD actively participates in its own safety monitoring by measuring the induced voltage across its electrodes and leads during the MRI scan. This self-measured data is transmitted to the MRI system, which uses it to adjust scan parameters, creating a closed-loop safety system that enables more aggressive and productive scanning while maintaining reliability
3Measurement precision
If existing temperature monitoring methods are used, then measurement capability is provided, but measurement precision is insufficient leading to inaccurate heating prediction and inadequate safety control
Solution Approach 1:
The system uses induced voltage as an intermediary measurement that can be obtained non-invasively during the MRI scan. This voltage measurement serves as a proxy for heating risk, providing real-time information about RF energy deposition in the IMD without requiring direct temperature measurement, thereby enabling precise heating prediction and control
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 and extended MRI scans by accurately predicting and managing heating in IMDs, allowing for higher power and longer durations without risking tissue damage, while reducing the need for restrictive MRI labeling and testing burdens.
Implementation Method 1
the induced voltage is induced in the at least one of the electrode or the lead conductor of the implantable medical device by a radio frequency (RF) field generated by a magnetic resonance imaging (MRI) scanner
Implementation Method 2
The implantable medical device may sense the induced voltage using sensing circuitry that is also used by the IMD to sense other electrical signals in the patient during the normal operation of the IMD outside of an MRI scan
Implementation Method 3
Such RF excitation may cause heating of the electrode(s) and/or conductive lead(s) during an MRI scan
Data Source
AI summary
In some examples, a method including detecting, via processing circuitry, an induced voltage in at least one of an electrode or a lead conductor of an implantable medical device, wherein the induced voltage is induced in the at least one of the electrode or the lead conductor of the implantable medical device by a radio frequency (RF) field generated by a magnetic resonance imaging (MRI) scanner; and modifying, via the processing circuitry, an MRI scan based on the detected induced voltage.