Simulating IMD Vibrations in MRI Scanners

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Solution Overview

Problem

Implantable medical devices (IMDs) face increased vibration responses due to higher slew rates of gradient magnetic fields in advanced MRI scanners, necessitating testing for reliability beyond current clinical MRI scanner capabilities.

Innovation Solution

A system simulates the mechanical response of IMDs to specified static and gradient magnetic fields by exposing them to stronger static fields and matching gradient field slew rates, using a test MRI scanner with vibration sensors and a processor to measure and analyze the induced vibrations, ensuring reliability in future MRI scanner generations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the slew rate of the gradient magnetic field is increased to produce more detailed scans, then the image quality and scan detail are improved, but the vibration response intensity of the IMD increases

Engineering Contradiction:

Improvescan detailVSAvoidvibration response intensity

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by conducting reliability testing of IMDs in advance using simulated gradient magnetic fields that replicate future MRI scanner slew rates. This allows the vibration response characteristics to be evaluated before the IMD is deployed in actual high-slew-rate MRI environments, enabling design modifications to mitigate harmful vibrations while maintaining image quality.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If testing is conducted in future generation MRI scanners with higher field strengths and slew rates, then the reliability assessment accuracy is improved, but the availability of such scanners for routine testing is reduced

Engineering Contradiction:

Improvereliability assessment accuracyVSAvoidtesting availability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent applies copying by creating simulated gradient magnetic fields that replicate the slew rate characteristics of future-generation MRI scanners. Instead of requiring access to actual future MRI scanners for testing, the invention uses available scanners with modified gradient waveforms that copy the desired high-slew-rate conditions, making reliability testing accessible and routine while maintaining assessment accuracy.

Inventive Principle:

Principle #26Copying

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 system effectively characterizes and reproduces the vibration response of IMDs, enabling reliable testing and validation of multiple devices without exposing them to extreme fields, thus ensuring performance in varied MRI environments.

Implementation Method 1

interactions between the static magnetic field and the gradient magnetic field produce vibrations in the IMD

Methodology Applied

Scientific EffectMagnetic field interaction: Lorentz Force

Data Source

PatentUS7383734B2Simulation of magnetic field induced vibrations in implantable medical devices

Publication Date: 2008.06.10 MEDTRONIC INC

AI summary

A mechanical response of an implantable medical device (IMD) to a first static magnetic field and a first gradient magnetic field slew rate is simulated by exposing the IMD to a second static magnetic field having a magnitude greater than the first static magnetic field and generating a second gradient magnetic field at the IMD such that a product of the second static magnetic field and a second gradient magnetic field slew rate is substantially equal to a product of the first static magnetic field and the first gradient magnetic field slew rate.