Analog Dispersive Delay Line for MR Signal Dynamic Range Compression
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Solution Overview
Problem
Magnetic resonance (MR) imaging and spectroscopy devices require specialized and costly RF modulators and receivers to handle high dynamic range MR signals, especially with the use of local MR receiver coils or coil arrays, which increases power and cost.
Innovation Solution
The implementation of an RF device with an analog dispersive delay line in both the transmit and receive chains to adjust the dynamic range of MR signals. This device includes a digital signal generator for generating a digital chirp signal, a D/A converter, an RF amplifier, and an analog dispersive delay line to increase dynamic range in the transmit chain, and a similar setup in the receive chain to reduce dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If specialized RF modulators and receivers with high speed ADCs and large numbers of bits are used to handle high dynamic range MR signals, then the dynamic range handling capability is improved, but the cost and power consumption increase
Solution Approach 1:
An analog dispersive delay line is introduced as an intermediary component in the receive chain to compress the dynamic range of MR signals before they reach the ADC. This mediator transforms the signal characteristics, allowing standard ADCs to handle signals that would otherwise require specialized high-performance converters, thereby reducing power consumption while maintaining dynamic range handling capability
Solution Approach 2:
The patent changes the temporal distribution parameter of the MR signal by applying dispersive delay, which spreads out the signal energy over time. This parameter transformation converts a high dynamic range signal concentrated in time into a lower dynamic range signal distributed over time, enabling the use of lower-power ADCs with fewer bits while preserving the essential signal information
2Reliability
If specialized RF modulators and receivers with high speed ADCs and large numbers of bits are used to handle high dynamic range MR signals, then the dynamic range handling capability is improved, but the cost increases
Solution Approach 1:
The analog dispersive delay line serves as a cost-effective intermediary that performs dynamic range compression using passive or low-cost analog components such as transmission lines with frequency-dependent delay characteristics. This approach replaces the need for expensive high-speed, high-resolution ADCs and specialized RF modulators, significantly reducing system cost while maintaining the ability to handle high dynamic range MR signals
Solution Approach 2:
The patent employs relatively simple and inexpensive analog dispersive delay line components rather than costly specialized digital signal processing hardware or high-performance ADCs. By using readily available analog components with frequency-dependent propagation characteristics, the system achieves dynamic range compression at a fraction of the cost of specialized high-end equipment
3Measurement precision
If local MR receiver coils or coil arrays are used to improve sensitivity and architectural advantages, then the imaging sensitivity is improved, but the power and cost of the receive chains increase due to high dynamic range requirements
Solution Approach 1:
The analog dispersive delay line is positioned as an intermediary between the local MR receiver coils and the ADC, performing dynamic range compression on the signals from each coil element. This allows local coils to maintain their sensitivity advantages while the mediator ensures that the subsequent electronics operate at lower power levels by handling signals with reduced dynamic range requirements
4Measurement precision
If local MR receiver coils or coil arrays are used to improve sensitivity and architectural advantages, then the imaging sensitivity is improved, but the cost of the receive chains increases due to high dynamic range requirements
Solution Approach 1:
The analog dispersive delay line acts as a cost-effective mediator that enables the use of local MR receiver coils without incurring the full cost penalty of specialized high-performance receive electronics. By compressing the dynamic range at an early stage using simple analog components, the system allows local coils to provide their sensitivity benefits while the downstream electronics can be implemented with standard, lower-cost components
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 solution reduces the dynamic range requirements in MR imaging and spectroscopy devices, allowing for retrofitting existing systems with minimal hardware modifications, and provides a cost-effective and efficient method for handling MR signals.
Implementation Method 1
an analog dispersive delay line connected to disperse the MR signal received by the MR receive coil to generate a dispersed MR signal
Data Source
Figure 1
Figure 2~3
AI summary
A radio frequency (RF) device for receiving or exciting a magnetic resonance (MR) signal includes an MR coil (22, 32) tuned to an MR frequency band, a digital signal processing chain (40, 44, 58, 70) at least partly tuned to operate at baseband, an analog signal processing chain (48, 50, 54, 60) operatively connected with the MR coil and at least partly tuned to operate at the MR frequency band, and an analog to digital (A/D) or digital-to-analog (D/A) converter (46, 56) connecting the digital signal processing chain and the analog signal processing chain. The analog signal processing chain includes an analog dispersive delay line (50, 60) tuned to impose a frequency-dependent signal delay (52, 62) that is monotonically increasing or monotonically decreasing over the MR frequency band. In more specific embodiments, the RF device may comprise an MR transmit chain (20), or an MR receive chain (30).