Multi-frequency RF Coil for Hyperpolarized MRI Calibration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current magnetic resonance imaging (MRI) techniques face challenges in calibrating systems for hyperpolarized 13C compounds due to insufficient natural abundance signals, leading to inaccurate flip angle calibration and signal loss, especially in areas lacking lipid-rich regions, which affects the image signal-to-noise ratio (SNR).
Innovation Solution
A multi-frequency RF coil capable of operating at proton, sodium, and carbon frequencies, with a frequency-shifting circuit loop that allows for prescan calibration using sodium frequency signals to determine optimal amplification levels for carbon frequency imaging, enabling accurate flip angle calibration and improved SNR without repositioning the subject or disconnecting cables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flip angle calibration is performed using natural abundance 13C signal, then calibration can be done in vivo, but the signal is insufficient leading to inaccurate calibration
Solution Approach 1:
The patent introduces an intermediary substance (lipid-rich material containing 13C) that mediates between the insufficient natural abundance 13C signal and the need for accurate flip angle calibration. This intermediary provides sufficient 13C signal for calibration while being compatible with in vivo conditions, thus resolving the contradiction between calibration accuracy and signal availability.
2Ease of operation
If a small phantom is used for calibration, then it can be inserted in the coil with the subject, but signal availability is limited leading to calibration inaccuracies
Solution Approach 1:
The patent merges the calibration phantom with the subject by positioning the lipid-rich material within the subject's body (e.g., in the liver or other lipid-containing organs) rather than as a separate external phantom. This merging allows the calibration signal to be obtained from within the imaging volume without requiring separate phantom insertion, thus simultaneously achieving ease of operation and sufficient signal availability.
3Measurement precision
If calibration is performed in a phantom with carbon enriched material, then flip angle calibration can be performed, but the phantom must be positioned near the coil where B1 is inhomogeneous
Solution Approach 1:
The patent inverts the conventional calibration approach by instead of placing the calibration material near the coil where B1 is inhomogeneous, it places the calibration material (lipid-rich tissue) at the isocenter where B1 is most homogeneous. This inversion of the calibration location resolves the contradiction between calibration capability and B1 field homogeneity.
4Measurement precision
If prescan calibration procedures are lengthy, then optimal imaging parameters can be determined, but signal loss occurs before imaging can begin
Solution Approach 1:
The patent applies preliminary action by performing flip angle calibration using the lipid-rich material before the hyperpolarized compound signal decays significantly. The lipid material provides a stable reference signal that allows rapid calibration to be performed in advance, determining optimal imaging parameters before the main imaging begins, thus resolving the contradiction between calibration precision and time loss.
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 allows for accurate flip angle calibration and enhanced image quality by utilizing the natural abundance of sodium for calibration, reducing signal loss and improving the signal-to-noise ratio in hyperpolarized MRI scans, making the system more commercially viable and effective.
Implementation Method 1
a frequency-shifting circuit loop that allows for prescan calibration using sodium frequency signals
Implementation Method 2
Magnetic resonance imaging (MRI) and nuclear magnetic resonance imaging (NMRI) are medical imaging techniques used to visualize certain structural aspects and functionality
Implementation Method 3
A multi-frequency RF coil capable of operating at proton, sodium, and carbon frequencies
Data Source
AI summary
A multi-frequency imaging radio frequency (RF) coil operational at three or more different frequencies, with a shifting frequency loop structure proximate the coil and switchably coupled to provide different frequencies when the loop structure is coupled to the coil. In one embodiment one of the frequencies is a proton frequency, one is a sodium frequency, and one of the frequencies is a carbon frequency. One example involves imaging examinations using hyperpolarized compounds.