Medical Device MRI Gradient Field Detection and Signal Processing
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Solution Overview
Problem
Magnetic Resonance Imaging (MRI) gradient magnetic fields and RF energy induce electrical signals in medical device lead wires, leading to erroneous cardiac event detection and compromised therapy delivery due to artifacts that mask actual cardiac signals.
Innovation Solution
A medical system with a transducer capable of detecting MRI gradient magnetic fields and switching to a signal processing mode that ignores or filters out induced electrical signals during MRI procedures, using orthogonal coils and a microprocessor to differentiate between cardiac and MRI-induced signals, and implementing a blanking period or signal conditioning to prevent false detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead wires are used to sense cardiac signals, then cardiac monitoring and therapy delivery are enabled, but MRI gradient fields and RF energy induce electrical signals in the lead wires causing erroneous detection
Solution Approach 1:
The device detects the presence of MRI gradient magnetic fields before they induce harmful electrical signals in the lead wires. Upon detection, the device proactively switches to a special signal processing mode that filters out MRI-induced artifacts, preventing false cardiac event detection rather than attempting to correct it afterward
Solution Approach 2:
A transducer is introduced as an intermediary component to detect MRI gradient magnetic fields. This transducer enables the device to sense the external MRI environment and trigger appropriate signal filtering mechanisms, acting as a mediator between the harmful external field and the cardiac sensing system
2Reliability
If signal filtering is applied during MRI to remove induced signals, then false detection is prevented, but actual cardiac signals may also be filtered out
Solution Approach 1:
The signal processing mode is dynamically adjusted based on the detected presence of MRI gradient fields. The device switches between normal sensing mode and MRI-compatible filtered mode, allowing optimal signal processing characteristics to be applied according to the operational environment, thereby preventing both false detection and signal loss
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
Prevents false detection of cardiac events during MRI, ensuring accurate therapy delivery by distinguishing between cardiac and MRI-induced signals, thereby maintaining proper pacing and defibrillation functions.
Implementation Method 1
A medical device including a transducer to detect a gradient magnetic field of a magnetic resonance imaging (MRI) machine
Implementation Method 2
MRI gradient magnetic fields and radio-frequency (RF) energy, which can induce electrical signals in the lead wires
Data Source
AI summary
A medical device includes a sensor for sensing for an MRI gradient magnetic field and a microprocessor configured to operate in a signal processing mode in which electrical signals induced by the gradient magnetic field are not counted as cardiac events.