NMR System with Multi-Coil RF Subsystem for Organ Selectivity
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Solution Overview
Problem
Traditional NMR systems with single-sided permanent magnets suffer from non-uniform magnetic fields, leading to inaccurate fat detection due to irregular excitation regions, which are not fully aligned with the target organs, resulting in detection errors.
Innovation Solution
An NMR measurement system with a magnet generating a static magnetic field and an RF subsystem that includes a main RF coil and secondary RF coils arranged peripherally, where pre-saturation pulse signals are used to align magnetization vectors in non-regions of interest parallel to the static magnetic field, reducing unwanted signals and enhancing selective excitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-sided permanent magnet is used to generate a static magnetic field, then the system achieves portability and low cost, but the magnetic field becomes extremely non-uniform resulting in an irregular saddle-shaped excitation region that causes detection errors
Solution Approach 1:
The patent divides the RF coil system into multiple independent coils (first RF coil, second RF coil, third RF coil, fourth RF coil) arranged at different positions. Each coil can be independently controlled to generate RF fields that collectively form a uniform excitation region, overcoming the limitation of single magnet systems while maintaining cost-effectiveness
Solution Approach 2:
The patent applies different functions to different parts of the system: the single-sided permanent magnet provides the static magnetic field for the entire detection region, while multiple RF coils are strategically positioned to create uniform RF field distribution specifically in the target organ region. This localized optimization of field uniformity resolves the contradiction between simple magnet design and detection accuracy
2Measurement precision
If multiple RF coils are added to improve field uniformity, then detection accuracy improves, but device complexity increases
Solution Approach 1:
The patent designs the RF coil system where multiple coils serve dual purposes: they collectively generate uniform RF field distribution for accurate detection, while their individual positioning and control enable selective excitation of target organs. This multi-functionality allows the system to achieve both field uniformity and organ selectivity without proportionally increasing complexity
Solution Approach 2:
The patent transitions from a single-point magnet configuration to a distributed multi-coil spatial arrangement. By distributing RF generation capability across multiple spatial positions (first, second, third, fourth RF coils at different locations), the system achieves uniform field distribution in three-dimensional space without requiring a complex single-coil structure
3Area of stationary object
If the excitation region is expanded to cover more tissue, then detection coverage improves, but selectivity decreases causing excitation of wrong regions
Solution Approach 1:
The patent employs dynamic control of multiple RF coils with adjustable phases and amplitudes. The system can dynamically adjust the RF field distribution pattern to match the specific geometry and position of target organs, achieving both adequate excitation coverage and high selectivity. This dynamic adaptability allows the excitation region to be optimized for each specific detection scenario
Solution Approach 2:
The patent incorporates signal processing that analyzes the NMR signals returned from different regions. By comparing signal characteristics from the excitation region with expected organ signals versus background tissue signals, the system provides feedback to adjust the RF coil excitation patterns, ensuring selective excitation of target organs while minimizing excitation of incorrect regions
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 achieves regional selective excitation, improving detection accuracy, reducing measurement time, and making the system more lightweight, cost-effective, and less operator-dependent, while minimizing the impact of motion and noise.
Implementation Method 1
The magnet is configured to generate a static magnetic field in a detection region
Implementation Method 2
The main RF coil is configured as a signal transceiver component of the RF subsystem to transmit a pulse sequence signal from the NMR spectrometer, which generates a pulse vector magnetic field intersecting with the static magnetic field in the detection region
Implementation Method 3
The secondary RF coils are configured as signal transmitting components of the RF subsystem to transmit a pre-saturation pulse signal from the NMR spectrometer before or during transmission of the pulse sequence signal, generating an RF field covering a non-region-of-interest (ROI) in the detection region
Implementation Method 4
The NMR spectrometer is configured to generate the pulse sequence signal... and to receive an echo signal from the detection region
Data Source
AI summary
A comprehensive and integrated solution, including a dedicated system structure and grounding mechanism, a main radio frequency (RF) coil to transmit and receive signal, secondary RF coils to saturate unwanted signals from non-region-of-interest (ROI) in the excited region, an RF shielding structure configured to shield the main RF coil from generating signals on the non-ROI, and an environmental noise active cancellation mechanism is proposed to construct an NMR system for non-invasive quantitative detection of organs, and further improves the target region selectivity and detection accuracy.