MRI Contrast Agent Concentration via Resonance Frequency Shift
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Solution Overview
Problem
Current MRI techniques face challenges in simplifying the process for quantitatively determining the concentration of gadolinium-based contrast agents due to uncertainties in relaxivity and the need for multiple calibration steps, which complicates quantitative perfusion imaging.
Innovation Solution
A method is introduced to measure contrast agent concentration by computing pre- and post-contrast resonance frequency maps, directly determining the concentration from intrinsic changes in resonance frequency caused by the contrast agent, rather than relying on relaxation time changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If relaxation time (T1) changes are used to determine contrast agent concentration, then quantitative perfusion imaging can be performed, but the process becomes complicated due to uncertainties in relaxivity and the need for multiple calibration steps
Solution Approach 1:
The patent changes the measurement parameter from relaxation time (T1) to resonance frequency. By using resonance frequency changes instead of T1 changes, the method eliminates the need for relaxivity calibration and multiple scan sequences, directly obtaining contrast agent concentration from the frequency shift without additional calibration steps
Solution Approach 2:
The patent extracts the concentration information directly from the resonance frequency change signal, separating the concentration measurement from the complex T1 relaxation measurement process. This extraction allows direct quantification without needing to account for relaxivity uncertainties or perform multiple calibration procedures
2Measurement precision
If multiple calibration steps are used to determine contrast agent concentration, then measurement accuracy can be improved, but the time required for imaging increases
Solution Approach 1:
The patent performs the concentration measurement directly during the contrast-enhanced imaging acquisition by monitoring resonance frequency changes in real-time. This eliminates the need for separate pre-contrast and post-contrast calibration scans, allowing quantitative concentration data to be obtained simultaneously with the perfusion imaging itself
Solution Approach 2:
The patent maintains continuous measurement of resonance frequency changes throughout the contrast enhancement period, providing continuous concentration data without interrupting the imaging process for calibration scans. This continuous approach ensures that concentration information is available throughout the entire perfusion cycle
3Adaptability or versatility
If relaxation time methods are used for quantitative perfusion imaging, then perfusion parameters can be calculated, but the complexity of the process reduces accessibility for clinical use
Solution Approach 1:
The patent changes the fundamental measurement parameter from T1 relaxation time to resonance frequency. This parameter change simplifies the imaging protocol by eliminating the need for multiple pulse sequences and relaxivity calibration, making quantitative perfusion imaging more accessible while maintaining the ability to calculate perfusion parameters
Solution Approach 2:
The patent allows the contrast agent itself to provide the calibration information through its own resonance frequency changes. The contrast agent's intrinsic magnetic properties cause measurable frequency shifts that directly reflect concentration, eliminating the need for external calibration phantoms or separate calibration 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 approach allows for accurate and simplified determination of contrast agent concentration, reducing uncertainties and calibration requirements, thereby enhancing the accessibility of quantitative perfusion imaging in MRI.
Implementation Method 1
the change in resonance frequency is caused by the magnetic susceptibility effect of the contrast agent on the resonance frequency of water protons
Data Source
AI summary
The present disclosure provides systems and methods for measuring a concentration of a contrast agent using magnetic resonance imaging (MRI). The method includes acquiring pre- and post-contrast data from a volume of a subject, where the pre-contrast data is acquired before a contrast agent is administered and the post-contrast data is acquired after the contrast agent is administered. Pre- and post-contrast resonance frequency maps are then computed, where the pre-contrast frequency map is based on one or more pre-contrast resonance frequency values, and the post-contrast resonance frequency map is based on one or more post-contrast resonance frequency values. The pre- and post-contrast frequency maps are then used to generate a resonance frequency change map that is subsequently used to generate a contrast agent concentration map that indicates a concentration of the contrast agent that was present at each voxel in the volume at the second time.