MRI Tracking via Gradient Coil Induction
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Solution Overview
Problem
Current methods for determining the location and orientation of medical devices within MRI systems face challenges such as image artifacts, electromagnetic interference, and limited accuracy, particularly when using external electromagnetic fields or RF signals, which complicate their integration with MRI scans.
Innovation Solution
The method employs time-varying magnetic gradients from orthogonal coils to measure induced electric potentials, allowing for real-time tracking of device location and orientation without requiring external field generation or modification of the MRI scanner, using a passive sensing approach that aligns with the MRI's gradient coil activations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external electromagnetic fields or RF signals are used to track device location, then tracking capability is improved, but image artifacts and electromagnetic interference increase
Solution Approach 1:
The patent uses the MRI system's own gradient coils as an intermediary to generate magnetic fields for tracking. Instead of introducing external electromagnetic field generators that cause artifacts, the solution leverages existing scanner components (gradient coils) to produce the necessary time-varying magnetic fields that induce measurable potentials in the tracking device's coils, thereby eliminating harmful interference while maintaining tracking accuracy
Solution Approach 2:
The tracking system is made self-service by using the MRI scanner's inherent gradient coil activations to generate the magnetic fields needed for tracking. The scanner's own operational fields are repurposed to simultaneously perform imaging and tracking functions, eliminating the need for separate external field generation systems that would create artifacts and electromagnetic interference
2Measurement precision
If external field generators are added to the MRI scanner for tracking, then tracking functionality is improved, but device complexity and scanner modification requirements increase
Solution Approach 1:
The patent achieves multi-functionality by enabling the gradient coils to serve dual purposes: generating magnetic fields for both MRI imaging and for tracking device location. The same hardware components perform multiple functions, eliminating the need for dedicated external field generators and reducing overall system complexity
Solution Approach 2:
The tracking functionality is provided self-service through the scanner's existing gradient coil system. Rather than requiring external additions, the scanner's own operational fields are utilized for tracking, making the system self-sufficient and avoiding structural modifications
3Measurement precision
If mechanical attachments or line of sight requirements are imposed on tracking devices, then tracking accuracy is improved, but ease of operation and device flexibility decrease
Solution Approach 1:
The patent replaces mechanical tracking systems (which require attachments, frames, or line-of-sight optical paths) with an electromagnetic sensing approach. Small coils attached to the device tip detect magnetic field potentials, providing contactless, attachment-free tracking that maintains accuracy while greatly improving device flexibility and ease of operation
Solution Approach 2:
The tracking method changes the measurement parameter from mechanical position detection to electrical potential measurement. By measuring induced potentials in response to time-varying magnetic fields, the system achieves accurate tracking without mechanical constraints, allowing free manipulation of flexible devices like catheters
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 accurate and stable tracking of medical devices within MRI systems, reducing image artifacts and electromagnetic interference, enabling real-time navigation during procedures while maintaining the integrity of MRI scans.
Implementation Method 1
measuring electrical potentials induced by time-variable magnetic fields in a set of miniature coils
Data Source
AI summary
Tracking based on the gradient fields of magnetic resonance imaging (MRI) scanners based on passive operation of the tracking system without any change of the scanner's hardware or mode of operation. To achieve better tracking performance, a technique to create a custom MRI pulse sequence is disclosed. Through this technique any standard pulse sequence of the scanner can be modified to include gradient activations specifically designated for tracking. These tracking gradient activations are added in a way that does not affect the image quality of the native sequence. The scan time may remain the same as with the native sequence or longer due to the additional gradient activations. The tracking system itself can use all the gradient activations (gradient activations for imaging and gradient activations for tracking) or eliminate some of the gradients and lock onto the specific gradient activations that are added to the custom pulse sequence.