CEST pH Calculation Using B1- and Temperature-Matched Standard Curves
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Solution Overview
Problem
Existing pH calculation methods using Chemical Exchange Saturation Transfer (CEST) imaging are prone to inaccuracies due to variations in saturation pulse intensity and temperature, which are not always constant, leading to unreliable pH value determination.
Innovation Solution
A pH calculating apparatus and method that utilizes a processing circuitry to obtain Z spectra from CEST imaging with a contrast agent containing substances with different pH responsiveness, calculates pH-dependent values, selects a standard curve based on B1 values, and determines pH values using a pH calculating function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the ratiometric method is used for pH calculation in CEST imaging, then pH imaging can be performed without dependency on CEST substance concentration, but the method requires constant saturation pulse intensity and temperature which are not always maintained in practice
Solution Approach 1:
The patent applies parameter changes by introducing multiple standard curves corresponding to different B1 values (saturation pulse intensities) and temperatures. Instead of using a single standard curve that assumes constant parameters, the system prepares multiple standard curves with different B1 values (e.g., 0.5 μT, 1.0 μT, 1.5 μT) and different temperatures (e.g., 25°C, 36°C, 37°C). The appropriate standard curve is selected based on the actual B1 value and temperature measured during imaging, thereby adapting the calculation to the actual experimental conditions and improving both accuracy and reliability.
2Measurement precision
If multiple standard curves for different B1 values are prepared, then pH calculation accuracy improves under varying saturation pulse intensity, but the complexity of the calculation system increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing multiple standard curves for different B1 values and temperatures before the actual pH measurement. The standard curves are prepared in advance using the formula MTRasym = f(pH, B1, T), where the relationships between MTRasym, pH, B1, and T are established beforehand. During actual imaging, the system only needs to measure the B1 value and temperature, then select and use the corresponding pre-prepared standard curve, which simplifies the real-time calculation process while maintaining high accuracy.
3Measurement precision
If temperature variations are accounted for in pH calculation, then measurement accuracy improves, but the complexity of controlling and monitoring experimental conditions increases
Solution Approach 1:
The patent applies feedback by measuring the actual temperature during CEST imaging and using this measured temperature to select the appropriate standard curve. The system includes temperature measurement functionality that provides real-time feedback on the actual temperature conditions. Based on this feedback, the system automatically selects the standard curve corresponding to the measured temperature range, thereby compensating for temperature variations without requiring complex active temperature control mechanisms.
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
Enhances the accuracy of pH value determination by accounting for variations in saturation pulse intensity and temperature, providing precise pH measurements.
Implementation Method 1
an imaging method based on Magnetic Resonance Imaging (MRI) using Chemical Exchange Saturation Transfer (hereinafter, 'CEST') has been proposed. Solute protons dissolved in water are chemically exchanged with water protons. The speed of such a chemical exchange is dependent on temperature and pH.
Implementation Method 2
Solute protons dissolved in water are chemically exchanged with water protons. The speed of such a chemical exchange is dependent on temperature and pH.
Implementation Method 3
resonance frequencies of protons vary depending on the state of the protons. Such changes in the resonance frequencies of protons are called 'chemical shifts'.
Data Source
AI summary
A pH calculating apparatus according to an embodiment includes processing circuitry that obtains a Z spectrum generated from a CEST imaging process by using, for a subject, a contrast agent containing types of substances having mutually-different responsiveness to pH during chemical shift imaging and including fall points of signal values corresponding to the types of substances; obtains information related to the subject; calculates a pH dependent value by using MR signal values corresponding to the fall points of the signal values; selects a standard curve indicating a pH value corresponding to the pH dependent value in accordance with the information, from among standard curves prepared in advance in accordance with the information; and determines a pH value based on the selected standard curve and the pH dependent value.