Magnetic Resonance Antenna Detuning for PET Compatibility
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Solution Overview
Problem
Existing methods for detuning magnetic resonance antennas are unsuitable for high-field imaging, especially when combined with PET devices, as they fail to effectively separate the natural resonance frequency from the operating frequency in magnetic fields greater than or equal to 3 Tesla.
Innovation Solution
A magnetic resonance antenna with parallel-running longitudinal antenna rods in a birdcage structure, equipped with radio-frequency switching elements at the end sections of the rods, which interrupt the resonant inductance and include parallel conductor elements to suppress eddy currents, and a compact supply unit for controlling these elements, ensuring effective detuning and minimizing interference with the main magnetic field and PET signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radio-frequency switching elements are arranged in the geometric center along the longitudinal antenna rods, then detuning can be achieved, but components disrupt the main magnetic field and attenuate PET signals
Solution Approach 1:
The radio-frequency switching elements are extracted from the geometric center region and relocated to the end sections of the longitudinal antenna rods. This spatial extraction removes the harmful components from the PET detection field of view, eliminating signal attenuation while preserving detuning functionality at the rod ends.
Solution Approach 2:
The switching elements are positioned at the longitudinal extremities of the antenna rods rather than in the central transverse plane. This dimensional relocation places components outside the PET angle of view while maintaining their electrical function for detuning the antenna resonance.
2Adaptability or versatility
If the birdcage structure is arranged in a bandpass structure for high-field imaging, then symmetry and space utilization improve, but detuning becomes more difficult
Solution Approach 1:
The antenna rods are segmented by introducing radio-frequency switching elements at their end sections. This segmentation allows independent control of resonance characteristics in each rod, enabling effective detuning of the overall birdcage structure while maintaining its symmetric bandpass configuration for high-field imaging.
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 solution enables precise control of the natural resonance frequency, effectively decoupling it from the operating frequency, reducing unwanted attenuation of PET signals and maintaining the integrity of the main magnetic field, even in high-field imaging conditions.
Implementation Method 1
a plurality of radio-frequency switching elements for interrupting at least a part of the longitudinal antenna rods in order to detune a natural resonance frequency with respect to an operating magnetic resonance frequency in radio frequency terms
Implementation Method 2
The longitudinal antenna rods each have at least two conductor elements running in parallel, as a result of which eddy currents resulting within the longitudinal antenna rods due to gradient fields may advantageously be at least partially suppressed and/or attenuated
Implementation Method 3
Magnetic resonance devices may operate with a plurality of different antennas (e.g., coils) for emitting radio-frequency pulses for the purpose of exciting nuclear magnetic resonance and/or for receiving induced magnetic resonance signals
Data Source
AI summary
The present embodiments include a magnetic resonance antenna having parallel-running longitudinal antenna rods arranged in a birdcage structure and antenna ferrules connecting the parallel-running longitudinal antenna rods at ends of the parallel-running longitudinal antenna rods in radio frequency terms. The magnetic resonance antenna includes a plurality of radio-frequency switching elements configured to interrupt at least a part of the parallel-running longitudinal antenna rods to detune a natural resonance frequency with respect to an operating magnetic resonance frequency in radio frequency terms. At least some radio-frequency switching elements of the plurality of radio-frequency switching elements are arranged at end sections of the parallel-running longitudinal antenna rods.