MR Phantom Resonating Volumes for Magnetic Field Mapping
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Solution Overview
Problem
Conventional methods for magnetic field mapping in MR imaging systems are cumbersome, expensive, and time-consuming, requiring complex and costly NMR magnetometers and holding apparatuses, which are also prone to damage during transport and maintenance, necessitating frequent recalibration.
Innovation Solution
A phantom with resonating volumes is used within the MR imaging system for 3D spectroscopic MR measurements, allowing the magnetic field to be evaluated directly using the MR imaging system itself, eliminating the need for separate magnetometers and simplifying the process by using phase-encoding gradients for accurate field mapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional NMR magnetometers and holding apparatuses are used for field mapping, then measurement capability is provided, but device complexity and cost increase significantly
Solution Approach 1:
The MR imaging system performs field mapping measurements using its own imaging sequences and signal processing capabilities, eliminating the need for external NMR magnetometers. The system maps magnetic fields by acquiring MR signals from phantoms at different locations and calculating field values from these signals, allowing the system to serve its own calibration needs.
Solution Approach 2:
The field mapping functionality is extracted from the complex external NMR magnetometer system and integrated into the MR imaging system itself. By using the imaging system's existing RF coils, gradient fields, and signal processing, the patent removes the need for separate specialized measurement equipment.
2Adaptability or versatility
If NMR magnetometers are transported for recalibration, then field mapping can be performed at new locations, but risk of damage and loss increases
Solution Approach 1:
The MR imaging system performs field mapping using its own integrated capabilities and standard imaging sequences, eliminating the need to transport external NMR magnetometers to different locations. The system can self-calibrate at any installation site using available phantom objects and the imaging system's own RF and gradient systems.
3Measurement precision
If conventional field mapping methods are used, then magnetic field can be measured, but measurement time increases
Solution Approach 1:
The field mapping process uses continuous MR imaging sequences that acquire signals from multiple phantom locations in succession without interrupting the measurement workflow. The system continuously collects data points and processes them through field calculation algorithms, maintaining efficient use of measurement time while achieving comprehensive field coverage.
Solution Approach 2:
The system performs field mapping measurements as part of the initial system setup and calibration process, establishing baseline field values before clinical operation begins. This preliminary field characterization enables subsequent shimming corrections to be applied efficiently.
4Ease of operation
If mechanical holding apparatus is used to position NMR magnetometer, then movement control is achieved, but influences on static magnetic field increase
Solution Approach 1:
The patent replaces the mechanical holding apparatus with a computational approach. Instead of physically positioning an external magnetometer using mechanical devices that generate magnetic disturbances, the system uses the MR imaging system's own gradient fields and signal processing to determine field values at various spatial locations, eliminating mechanical interference with the static magnetic field.
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 reduces the complexity and cost of magnetic field mapping, enhances accuracy, and allows for quicker recalibration, as the MR imaging system can perform the necessary measurements with high precision, reducing the risk of equipment damage during transport and maintenance.
Implementation Method 1
Conventional measurement methods employ a Nuclear Magnetic Resonance (NMR) magnetometer or an array of such magnetometers. The NMR magnetometer is moved within the static magnetic field of the main magnet to desired sample locations in order to perform the required measurements
Implementation Method 2
In magnetic resonance (MR) imaging systems, a main magnet is used to generate a strong static magnetic field
Data Source
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AI summary
The present invention provides a phantom (200) for use in a magnetic resonance (MR) imaging system (110) with a set of resonating volumes (206) positioned in a base body (202), whereby the base body (202) has a spherical or ellipsoid shape in accordance with a volume of interest (203) of the MR imaging system (110), and the resonating volumes (206) are located at a circumference of the base body (202). The phantom is used in a method for evaluating the magnetic field of a main magnet (114) of a magnetic resonance (MR) imaging system (110), comprising the steps of positioning the phantom (200) within the main magnet (114), performing a 3D spectroscopic MR measurement of the phantom (200) using the MR imaging system (110), thereby measuring resonances of the resonating volumes (206), assigning the measured resonances to the resonating volumes (206), and evaluating the magnetic field of the main magnet (114) from the MR measurement of the phantom (200) based on the measured resonances of the resonating volumes (206). Accordingly, the MR imaging system itself is directly used for determining the magnetic field of its main magnet. Accordingly, the MR imaging system itself can be used as measurement equipment, instead of a separate NMR magnetometer, which is required for conventional determination of the magnetic field.