MRI RF Coil SAR Calculation via Input Reflection Coefficient
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Solution Overview
Problem
Current magnetic resonance imaging (MRI) systems face challenges in accurately determining the Specific Absorption Rate (SAR) value, which is crucial for ensuring patient safety during scans, especially for vulnerable groups like infants and pregnant women, due to the complexity and cost of existing methods for measuring radio-frequency energy absorption.
Innovation Solution
A magnetic resonance imaging system that includes a radio-frequency transmitting coil, a reflection coefficient determining module, a resistance value determining module, and a SAR value determining module, which calculate the SAR value by analyzing the frequency responses of the radio-frequency transmitting coil with and without a load, allowing for more accurate assessment without the need for additional hardware like a pick-up coil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pick-up coil is used to measure coil loss in real time, then the accuracy of SAR value measurement is improved, but the hardware cost and system complexity increase
Solution Approach 1:
The patent extracts the measurement function from a separate pick-up coil hardware component and integrates it into the existing radio-frequency transmitting coil system. By measuring the input reflection coefficient of the transmitting coil itself, the system obtains coil loss information without requiring an additional measurement coil, thereby reducing hardware complexity while maintaining measurement accuracy.
Solution Approach 2:
The radio-frequency transmitting coil serves multiple functions: it transmits radio-frequency power for imaging and simultaneously acts as the measurement element for determining coil loss through input reflection coefficient measurement. This multi-functionality eliminates the need for a dedicated pick-up coil, reducing system complexity while preserving SAR measurement capability.
2Reliability
If a conservatively estimated coil loss value is used, then the safety is improved, but the scanning parameter selection is limited and image quality deteriorates
Solution Approach 1:
The system implements real-time feedback measurement of coil loss through input reflection coefficient measurement. This actual measurement data replaces conservative estimates, allowing the system to accurately determine SAR values while maintaining safety. The feedback mechanism enables optimal scanning parameter selection by providing真实 information about actual power loss in the coil.
3Measurement precision
If additional hardware like a pick-up coil is added, then the measurement accuracy is improved, but the cost and complexity increase
Solution Approach 1:
The radio-frequency transmitting coil performs self-measurement of its own loss characteristics through input reflection coefficient measurement. The coil serves itself as both the power transmission element and the measurement subject, eliminating the need for separate measurement hardware like a pick-up coil. This self-service approach reduces manufacturing cost while maintaining measurement precision.
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 a more accurate SAR value calculation, enabling safer and higher-quality imaging by reducing the complexity and cost of the system while ensuring proper scanning parameters, with a maximum error of 3.6% compared to traditional methods.
Implementation Method 1
a radio-frequency transmitting coil is used to transmit a radio-frequency excitation pulse to a tissue to be imaged, and a large part of the power of the radio-frequency excitation pulse is absorbed by the human body and converted into thermal energy
Implementation Method 2
acquire a frequency response of a first input reflection coefficient of the radio-frequency transmitting coil when having no load and a frequency response of a second input reflection coefficient thereof when having the scanned object; determine a resistance value of the radio-frequency transmitting coil on the basis of the frequency response of the first input reflection coefficient
Data Source
AI summary
In the present invention, provided are a magnetic resonance imaging system, a method for determining a SAR value of a magnetic resonance imaging system, and a computer-readable storage medium. The system comprises a radio-frequency transmitting coil, configured to receive radio-frequency power from a radio-frequency transmitting link and transmit radio-frequency power required for imaging to a scanned object. The system further comprises a reflection coefficient determining module, a resistance value determining module, and a SAR value determining module. The reflection coefficient determining module is configured to acquire a frequency response of a first input reflection coefficient of the radio-frequency transmitting coil when having no load and a frequency response of a second input reflection coefficient thereof when having the scanned object. The resistance value determining module is configured to determine a resistance value of the radio-frequency transmitting coil on the basis of the frequency response of the first input reflection coefficient, and determine a parallel resistance value of the radio-frequency transmitting coil and the scanned object on the basis of the frequency response of the second input reflection coefficient. The SAR value determining module is configured to calculate a SAR value of the scanned object on the basis of the resistance value of the radio-frequency transmitting coil and the parallel resistance value.