Twistable Halbach Ring Magnets for Hybrid MPI MRI CT Imaging
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Solution Overview
Problem
Current hybrid imaging apparatuses cannot simultaneously perform Magnetic Particle Imaging (MPI), Magnetic Resonance Imaging (MRI), and Computed Tomography (CT) due to incompatible magnetic field requirements for each modality, with existing solutions either lacking a suitable MPI magnetic field or interfering with MRI and CT measurements.
Innovation Solution
A hybrid imaging apparatus featuring a magnet arrangement with a pair of twistable Halbach ring magnets, allowing for the generation of both a field-free region for MPI and a homogeneous magnetic field for MRI, along with a CT unit that can rotate with the magnet arrangement to minimize stray fields, enabling simultaneous or sequential data recording across multiple imaging modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a magnet arrangement generates a magnetic field with a gradient B1 and a field-free region for MPI measurements, then MPI imaging capability is achieved, but the same arrangement cannot generate a static homogeneous main magnetic field required for MRI measurements
Solution Approach 1:
The magnet arrangement incorporates rotatable ring magnets that can be dynamically reconfigured between different orientations. The ring magnets can be rotated to achieve either a homogeneous field configuration for MRI or a field-free region configuration for MPI, allowing the same physical apparatus to adapt to different imaging modalities without requiring separate magnet systems
Solution Approach 2:
The patent designs a universal magnet arrangement using Halbach ring magnets that can serve multiple functions. By rotating the ring magnets to different angular positions, the same magnet arrangement can generate the homogeneous main magnetic field needed for MRI or the gradient field with field-free region needed for MPI, making the imaging apparatus versatile across multiple modalities
2Reliability
If permanent magnets in a Halbach configuration are used to generate the main magnetic field for MRI, then a homogeneous field is achieved, but the arrangement cannot generate the required magnetic field for MPI measurements
Solution Approach 1:
The Halbach ring magnets are designed to be rotatable, allowing dynamic reconfiguration of the magnetic field pattern. When the rings are in a specific orientation, they produce a homogeneous field suitable for MRI; when rotated to a different orientation, they produce the field-free region pattern required for MPI, thus maintaining field quality across different modalities
Solution Approach 2:
The patent changes the angular orientation parameter of the Halbach ring magnets to transform the magnetic field characteristics. By adjusting the rotation angle of the ring magnets, the system transitions between producing a homogeneous field (for MRI) and producing a field with a field-free region (for MPI), maintaining reliable field quality for each modality through parameter adjustment
3Adaptability or versatility
If the magnet arrangement is rotated to achieve different field configurations, then adaptability between MPI and MRI modes is improved, but stray magnetic fields may interfere with CT measurements
Solution Approach 1:
The imaging apparatus is divided into functionally independent segments: the magnet arrangement for MPI/MRI operations and the CT unit for X-ray imaging. This segmentation allows the CT unit to operate independently without being affected by the magnetic field configurations of the magnet arrangement, minimizing stray field interference while maintaining adaptability across imaging modes
Solution Approach 2:
The patent introduces a mechanically coupled rotation system that acts as an intermediary between the magnet arrangement and the CT unit. This intermediary mechanism coordinates the rotation of both components together, ensuring that when the magnet arrangement is rotated to achieve different field configurations, the CT unit rotates correspondingly to maintain proper alignment and minimize interference from stray magnetic fields
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
Enables the simultaneous or sequential acquisition of high-quality images using MPI, MRI, and CT modalities at the same location without moving the object, by optimizing the magnetic field configurations and using a shift field coil system to reduce drive field amplitudes and minimize adverse effects on the subject.
Implementation Method 1
permanent magnets in a Halbach configuration. In the case of a Halbach ring, the magnetization direction of the lateral ring side has a continuous rotation along the lateral profile in the plane perpendicular to the ring axis
Implementation Method 2
a static, homogeneous main magnetic field which is used to polarize the nuclear magnetization is used in the case of magnetic resonance imaging (MRI) measurements
Implementation Method 3
a magnetic field with a gradient B1 and a field-free region must be made available for MPI measurements
Data Source
AI summary
A hybrid imaging apparatus for imaging an object to be examined located in a sample volume can be operated in an MPI mode and in at least one further imaging mode and comprises a magnet arrangement embodied to generate, in the MPI mode, a magnetic field with a gradient B1 and a field-free region in the sample volume, wherein the magnet arrangement comprises a ring magnet pair with two ring magnets in a Halbach dipole configuration, which are arranged coaxially on a common Z-axis that extends through the sample volume, wherein the ring magnets are arranged so as to be twistable relative to one another about the Z-axis. Consequently, it is possible to generate magnetic fields that meet the requirements of both MRI and MPI such that the hybrid imaging apparatus can be equipped for measurements in various imaging modes, including MPI, MRI and CT.