Computational MRI Safety Assessment for Implanted Devices
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Solution Overview
Problem
Current methods for assessing the safety of implanted medical devices during MRI procedures are inadequate, as they do not accurately predict RF-induced heating and tissue damage, leading to inappropriate denial of MRI access for millions of patients with pacemakers and other devices.
Innovation Solution
A computational tool that predicts the interaction between MRI electromagnetic fields and implanted devices using patient-specific and device-related information, incorporating factors like device type, orientation, materials, MRI system parameters, and patient biometrics to assess the risk of heating and device damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MRI safety assessment methods are used, then patient safety is compromised due to inaccurate RF-induced heating predictions, but this leads to overly conservative denials of MRI access for millions of patients with implanted devices
Solution Approach 1:
The patent changes the parameters used in safety assessment from simplified in vitro measurements to in vivo physiological parameters including tissue permittivity, conductivity, blood flow rates, and device orientation angles. This allows accurate prediction of RF-induced heating while enabling safe MRI access for patients with previously contraindicated devices
Solution Approach 2:
The patent replaces mechanical in vitro testing methods with computational electromagnetic modeling that simulates the complex interaction between MRI RF fields and implanted devices within the human body. This substitution enables precise prediction of heating patterns without requiring conservative safety margins that deny MRI access
2Ease of operation
If simplified in vitro safety tests are used, then the testing process is simple and quick, but the results do not account for patient-specific information such as device placement, orientation, and physiological heat transfer mechanisms
Solution Approach 1:
The patent performs preliminary acquisition of patient-specific information including device type, implantation location, orientation, and patient anatomical characteristics before conducting the safety assessment. This preliminary data collection enables the computational model to accurately predict in vivo heating patterns without requiring complex real-time measurements during the actual assessment process
Solution Approach 2:
The patent creates a computational model that copies and simulates the actual patient-specific scenario including device geometry, tissue properties, and physiological conditions. This virtual copy allows accurate prediction of RF-induced heating while maintaining the simplicity of a pre-computed assessment rather than requiring complex physical measurements
3Device complexity
If current extrapolation methods are used to predict in vivo behavior from in vitro data, then the assessment process is straightforward, but the arbitrary abstractions and simplifying assumptions prevent reliable determination of safe exposure conditions
Solution Approach 1:
The patent changes from arbitrary abstraction parameters to physiologically accurate parameters including tissue permittivity, conductivity, blood flow rates, and device orientation. This parameter transformation enables reliable determination of safe exposure conditions by accurately representing the complex interaction between MRI fields and implanted devices in the human body
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 approach provides a personalized, precision healthcare method to safely assess and increase access to MRI for patients with implanted devices, improving patient safety and reducing unnecessary denials of critical diagnostic scans.
Implementation Method 1
Exposure of an implanted medical device to the electromagnetic fields generated by an MRI system can damage surrounding tissue, reduce the effectiveness of the device, promote migration of the device, or cause tissue necrosis. When electrically conductive materials are subjected to oscillating magnetic fields, electric currents are induced, which cause heating
Implementation Method 2
When electrically conductive materials are subjected to oscillating magnetic fields, electric currents are induced, which cause heating and increase the temperature in the surrounding tissue
Implementation Method 3
the currently accepted standard test method (ASTM F2182) for measuring RF induced heating does not accurately predict in vivo tissue damage or account for physiologic heat transfer mechanisms
Data Source
AI summary
Disclosed is a method for determining, among other things, the temperature profile of a medical implant in a patient when subjected to an MRI scan or machine, thus enabling a determination of the risk of temperature induced tissue necrosis or damage to the implant. The specific position of the implant in the patient changes the temperature dispersion in the body and is accounted for in the creation of the temperature profile. The method includes mapping with an imaging unit location, size and orientation of the medical implant in a patient, and storing the location, size and orientation in a mapped data. Then, translating the data to a model patient of gender, age, weight, height, and body structure of the patient with a model medical implant. Further, determining the parameters of an MRI unit to be used and computing the temperature profile of the implant to ascertain temperature impact.