MRI Catheter Antenna Layout for Tip Visibility and Low RF Heating
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Solution Overview
Problem
Conventional interventional MRI devices face challenges in accurately visualizing the distal tip and shaft of catheters due to poor signal-to-noise ratio and RF-induced heating, which are exacerbated by the use of multiple RF receiver antennas and impedance mismatches with surrounding anatomy.
Innovation Solution
The development of RF receiver antennas with adjustable impedance sections formed by alternating conductive layers and insulating materials, printed directly onto the device, allowing precise control of signal profile and minimizing RF-induced heating by matching impedance with surrounding anatomy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple RF receiver antennas are used for device visualization, then the coverage area for visualizing both distal tip and shaft is improved, but the device profile and mechanical performance are adversely affected
Solution Approach 1:
The patent combines multiple antenna functions into a single integrated antenna structure. The single antenna is designed with specific geometric configurations and conductor arrangements that enable it to perform both distal tip visualization and shaft visualization functions that traditionally required multiple separate antennas, thereby reducing device profile while maintaining comprehensive visualization coverage.
Solution Approach 2:
The single antenna is designed to serve multiple visualization functions simultaneously. By configuring the antenna with specific conductor geometries, insulation layer arrangements, and impedance characteristics, it can detect signals from both the distal tip region and the shaft region, making the antenna universal for multiple visualization purposes without requiring separate dedicated antennas for each function.
2Ease of manufacture
If conventional insulated or bare conductors are used in RF receiver antennas, then fabrication is simplified, but fine tuning of characteristic impedance values to optimize signal profile is not practical
Solution Approach 1:
The patent applies local quality by creating different impedance characteristics in different sections of the antenna conductors. By varying the conductor geometry (width, thickness, spacing) and insulation layer properties at specific locations along the antenna, it achieves localized impedance control that optimizes the signal profile for different visualization regions while maintaining overall fabrication simplicity through a printed circuit approach.
Solution Approach 2:
The patent changes physical parameters of the conductor and insulation structure to control impedance characteristics. By adjusting conductor width, thickness, spacing between conductors, and insulation layer properties, the design achieves fine tuning of characteristic impedance values across different antenna sections, enabling optimization of signal reception profiles without complicating the overall fabrication process.
3Measurement precision
If highly conductive antenna components and transmission lines are used for minimal signal loss, then device visualization signal quality is improved, but RF induced heating risk increases
Solution Approach 1:
The patent optimizes the electrical parameters of the antenna and transmission line to achieve a balance between signal quality and heating reduction. By carefully selecting conductor materials, geometries, and insulation properties, the design minimizes signal loss while controlling the electrical length and current distribution to reduce RF-induced heating, achieving acceptable visualization quality with reduced thermal risk.
Solution Approach 2:
The insulation layers serve as intermediaries between the conductive elements. By strategically placing and dimensioning insulation layers with specific dielectric properties, the patent mediates the electromagnetic field distribution, reducing direct current paths that cause heating while maintaining effective signal transmission, thus acting as a thermal and electromagnetic buffer between the conductors and surrounding tissues.
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 enables clear visualization of both the tip and shaft of interventional devices during MRI procedures without altering mechanical performance and reduces RF-induced heating, ensuring patient safety and improved imaging clarity.
Implementation Method 1
After RF excitation through the RF body coil of MRI scanner, the excited hydrogen protons within the body relax back and emit RF waves. These RF waves can be picked up through RF receiver antennas that are in close vicinity of these hydrogen protons.
Implementation Method 2
The SNR (signal to noise ratio) of the antenna is closely related to tuning of the antenna to the Larmor frequency (resonance frequency) of the MRI scanner and also matching with impedance of the RF coil plug of the scanner.
Implementation Method 3
The SNR (signal to noise ratio) of the antenna is closely related to tuning of the antenna to the Larmor frequency (resonance frequency) of the MRI scanner
Data Source
AI summary
The present disclosure provides medical devices having MRI-compatible circuitry. Preferably, the devices do not project an enlarged profile, yet their position can be determined during an iMRI procedure. Illustrative embodiments of such a device can include a base surface, a first conducting layer disposed on the base surface, a first insulating layer disposed over at least a portion of the first conducting layer, and a second conducting layer disposed over at least a portion of the first insulating layer.