Local Coil Frequency Mixing for Flexible MRI Multiplexing
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Solution Overview
Problem
Magnetic resonance scanners face limitations in flexibility when selecting frequencies for frequency-division multiplexing, particularly in systems with lower magnetic fields, where traditional frequency schemes may cause interference due to intermediate frequencies.
Innovation Solution
A local coil device with an auxiliary mixer generates two mixed frequency signals from two auxiliary frequency signals, allowing for flexible selection of frequencies and decoupling the selection process, using diode distortion or digital signal processing to produce intermodulation products, and employing diplexers and bandpass filters for signal separation and filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional frequency schemes are used in lower magnetic field systems, then frequency-division multiplexing can be implemented, but interference occurs due to intermediate frequencies
Solution Approach 1:
The patent changes the frequency parameters by generating mixed frequency signals locally at the antenna coil rather than using traditional centralized auxiliary frequency signals. This parameter change allows the system to operate effectively in lower magnetic field systems where traditional frequency schemes cause interference, thereby resolving the contradiction between reliable signal transmission and interference avoidance
2Adaptability or versatility
If auxiliary frequency signals are generated centrally and distributed to local coils, then frequency-division multiplexing is achieved, but flexibility in frequency selection is reduced
Solution Approach 1:
The patent segments the frequency generation function by placing a frequency generator at each antenna coil location rather than having a single centralized generator. This segmentation enables each local coil to independently select and generate its own mixed frequency signals, significantly improving frequency selection flexibility while eliminating the need for complex centralized distribution systems
Solution Approach 2:
Instead of the traditional approach where auxiliary frequency signals are generated centrally and distributed to local coils, the patent inverts this architecture by having each local coil generate its own auxiliary frequency signals locally. This inversion fundamentally changes the system architecture to achieve both flexibility and simplified complexity
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 enhances the flexibility and precision of frequency selection, reducing interference and enabling effective signal transmission in lower magnetic field systems, while simplifying circuitry and reducing costs.
Implementation Method 1
Mixing is understood to refer to signal processing which produces intermodulation products of the first and/or second auxiliary frequency signal. This may be achieved analogously by non-linear characteristics, for example, by diodes or amplifier elements. In digital signal processing, for example, multiplication, potential or exponential functions or also binary functions such as AND and/or OR functions are conceivable for generating intermodulation products.
Data Source
AI summary
The disclosure relates to a local coil with a device for providing a first mixed frequency signal and a second mixed frequency signal by a first auxiliary frequency signal and a second auxiliary frequency signal. The device has an auxiliary mixer configured to generate the second mixed frequency signal from the first auxiliary frequency signal and the second auxiliary frequency signal. The local coil has a signal input including a first signal connection to the device. The local coil is configured to jointly receive the first auxiliary frequency signal and the second auxiliary frequency signal by way of the signal input and supply them to the device by way of the first signal connection.