Magnetic Resonance Relaxation Time Measurement via Spin-Cavity Coupling Control
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Solution Overview
Problem
The measurement of spin lattice relaxation time (T1) in magnetic resonance techniques is hindered by spin-cavity coupling, leading to distorted spectra and inaccurate relaxation time readings due to changes in the coupling constant, especially when the spin concentration is high or the Q value of the resonance circuit is high.
Innovation Solution
Forming multiple spin-cavity coupling states by varying the sample amount or Q value of the resonance circuit, calculating spin-cavity coupling constants, and measuring apparent relaxation times to determine the true relaxation time by fitting a quadratic function to the relationship between these constants and relaxation times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic resonance measurement is performed on samples with high spin concentration or high Q-value resonance circuits, then the signal intensity and measurement sensitivity are improved, but the spin-cavity coupling causes distorted spectra and inaccurate relaxation time readings
Solution Approach 1:
The patent applies parameter changes by systematically varying the Q-value of the resonance circuit across multiple measurements. By measuring apparent relaxation times at different Q-values and extrapolating to the limit of zero spin-cavity coupling (Q-value approaching zero or infinity), the method eliminates the distorting effect of spin-cavity coupling and obtains the true relaxation time of the sample.
2Measurement precision
If the Q value of the resonance circuit is increased to improve signal detection, then the measurement sensitivity is enhanced, but the spin-cavity coupling constant changes leading to measurement errors
Solution Approach 1:
The patent employs preliminary action by performing multiple measurements at different Q-values before the final determination of relaxation time. This preliminary series of measurements at varying coupling conditions allows for the construction of a relationship curve between apparent relaxation time and spin-cavity coupling constant, which is then used to extrapolate the true relaxation time independent of coupling effects.
3Measurement precision
If multiple measurements are performed with varying Q values to eliminate spin-cavity coupling effects, then the true relaxation time can be accurately determined, but the measurement time and procedure complexity increase
Solution Approach 1:
The method applies self-service by using the measurement system itself to generate the necessary variation in coupling conditions. By systematically adjusting the Q-value of the existing resonance circuit and performing measurements at each setting, the system self-generates the data needed to construct the extrapolation curve, eliminating the need for additional external equipment or complex intervention procedures.
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 method allows for the accurate determination of relaxation times even under conditions with significant spin-cavity coupling, ensuring consistent apparent relaxation times and enabling the calculation of true relaxation times specific to the sample.
Implementation Method 1
Nuclear magnetic resonance (NMR) measuring apparatuses and electron spin resonance (ESR) measuring apparatuses are conventionally known as representative magnetic resonance measuring apparatuses
Implementation Method 2
a strong interaction different from the magnetic resonance is manifested between the spin and the resonance circuit (i.e., the cavity or the NMR probe), which may be called 'spin-cavity coupling'
Data Source
AI summary
A method includes forming N spin-cavity coupling states that are mutually different in coupling state between a cavity accommodating a sample therein and a spin of the sample, calculating N values of spin-cavity coupling constant, measuring N values of apparent relaxation time through magnetic resonance measurement applied on the sample, and calculating relaxation time corresponding to specific spin-cavity coupling constant based on the relationship between the N values of spin-cavity coupling constant and the N values of apparent relaxation time.