AIMD Inductor-Based MRI Detection System
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Solution Overview
Problem
Existing MRI detection systems for active implantable medical devices (AIMDs) require separate sensors and larger device sizes, which compromise patient comfort and ease of implantation, while also being cumbersome for MRI procedures.
Innovation Solution
The proposed MRI detection system utilizes existing ferromagnetic cores of inductors or dedicated inductors within the AIMD to sense magnetic fields, triggering signals when electrical properties cross thresholds, allowing the AIMD to automatically switch to an MRI-safe mode without the need for external sensors or larger device sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate sensors are added to detect MRI magnetic fields, then MRI detection capability is improved, but device size and complexity increase
Solution Approach 1:
The patent combines the MRI detection function with existing inductors (charging coil, boost inductor, or dedicated sensing inductor) that are already present in the AIMD. The controller monitors electrical properties (inductance, voltage, current) of these existing components to detect MRI magnetic fields, eliminating the need for separate dedicated sensors and reducing device complexity while maintaining reliable MRI detection capability
Solution Approach 2:
The existing inductors in the AIMD are made to serve dual purposes: their original function (charging, power conversion, or signal processing) and MRI field sensing. By monitoring changes in their electrical properties under MRI conditions, the same components perform multiple functions, reducing overall device complexity and size
2Reliability
If manual configuration is required before MRI, then MRI safety is improved, but ease of operation deteriorates
Solution Approach 1:
The AIMD performs self-detection of MRI conditions by monitoring electrical properties of its internal inductors, and automatically switches to MRI-safe operational modes without requiring manual intervention from the patient. The device serves itself by detecting the MRI environment and adjusting its operation autonomously, improving ease of operation while maintaining MRI safety
Solution Approach 2:
The controller continuously monitors electrical properties (inductance, voltage, current) of the inductors and uses this feedback to detect when the device is in an MRI environment. Based on this real-time feedback, the controller automatically adjusts stimulation parameters or disables functions to ensure MRI safety, eliminating the need for manual pre-configuration
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
This solution enables AIMDs to safely enter MRI mode even if the patient forgets to modify the stimulator, allows for emergency scans without prior knowledge of the implanted device, and simplifies the MRI process for patients with AIMDs, reducing the need for manual interactions and external controllers.
Implementation Method 1
The presence of a magnetic field of an MRI may saturate the ferromagnetic cores of the inductors, thereby decreasing magnetic permeability (e.g., ability to store magnetic flux) and, thus, decreasing the inductance of the inductors
Implementation Method 2
utilizing already existing ferromagnetic cores of inductors, charging coils within the AIMD
Implementation Method 3
When an inductor is saturated, its ability to store energy in a magnetic field is limited
Data Source
AI summary
An MRI detection system for an AIMD. The detection system includes utilizing monitoring or detecting a signal from a magnetic field sensitive element. The magnetic field sensitive element may include at least one of an inductor within the IPG, a reed switch, and Hall sensor. The magnetic field sensitive element may assist the AIMD in detecting an MRI to trigger an MRI safe mode in order to prevent adverse effects when an MRI scan is performed.