MRI Artifact Reduction via RF Polarization Diversity
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Solution Overview
Problem
Magnetic resonance imaging (MRI) scans with metal objects, such as implants, suffer from artifacts due to distortions in the static B0 field and radio-frequency field, leading to image impairments and signal fluctuations, particularly at high field intensities.
Innovation Solution
Acquiring multiple MRI images with different polarizations of the radio-frequency field and combining the image data using a B1 map or iterative reconstruction techniques to reduce signal variations and artifacts, while allowing for undersampling to save time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple MRI images with different radio-frequency field polarizations are acquired and combined, then artifact reduction and signal homogeneity are improved, but examination time and data acquisition complexity increase
Solution Approach 1:
The examination is divided into multiple separate acquisitions, each with a specific radio-frequency field polarization. By segmenting the data acquisition process into distinct polarization components (e.g., different B1 field orientations), the system can optimize each acquisition for specific artifact reduction purposes while maintaining overall image quality through subsequent combination.
Solution Approach 2:
The radio-frequency field polarization is dynamically varied between different acquisitions. Instead of using a fixed polarization, the system dynamically changes the polarization state (e.g., switching between different B1 field orientations) to optimize signal characteristics and reduce artifacts in different regions, then combines these dynamic acquisitions for the final image.
2Manufacturing precision
If multiple MRI images with different radio-frequency field polarizations are acquired and combined, then artifact reduction and signal homogeneity are improved, but device complexity and processing requirements increase
Solution Approach 1:
The complex artifact reduction problem is segmented into manageable components by acquiring separate images for different polarization states. Each acquisition is processed independently with simpler algorithms, and the results are combined using structured processing techniques, reducing overall processing complexity compared to a single complex acquisition approach.
Solution Approach 2:
The system changes the polarization parameter of the radio-frequency field between different acquisitions. By varying this key parameter (polarization state) rather than changing multiple parameters simultaneously, the system simplifies the data processing requirements while still achieving comprehensive artifact reduction through the combination of parameter-specific acquisitions.
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 effectively reduces artifacts by achieving more homogeneous signal distribution across the examination region, particularly around metal objects, thereby improving image quality without data loss.
Implementation Method 1
Acquiring multiple MRI images with different polarizations of the radio-frequency field and combining the image data using a B1 map or iterative reconstruction techniques to reduce signal variations and artifacts
Implementation Method 2
Magnetic resonance imaging is widely known and involves the use of radio-frequency excitation of nuclear spins in an examination subject that deflect the spins from alignment produced by a basic magnetic field (B0 field)
Data Source
AI summary
In a method for reducing artifacts during the acquisition of magnetic resonance data relating to a region undergoing examination in an examination subject by operation of a magnetic resonance apparatus, a first magnetic resonance image with a first polarization of a radio-frequency field of the magnetic resonance scanner, which is described by amplitudes and/or phases of coil elements thereof, at least one further magnetic resonance image with at least one further polarization of the radio-frequency field of the magnetic resonance scanner, also described by amplitudes and/or phases of the coil elements, wherein the at least one further polarization differs from the first polarization, and of image data from the first and from at least one further magnetic resonance image are combined.