B0 Field Estimation for MRI Using Scout Image Analysis
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Solution Overview
Problem
Current Magnetic Resonance Imaging (MRI) techniques face challenges in efficiently determining B0 field inhomogeneities, which are essential for producing high-quality images. Existing methods are time-consuming and may not accurately account for subject movement or anatomical variations outside the imaged region.
Innovation Solution
The proposed method utilizes an initial magnetic resonance image, such as a scout or survey image, to estimate B0 field mapping for subsequent image acquisitions. This approach allows for the prediction of B0 distribution across larger anatomical regions, accounting for subject movement and anatomical variations, without the need for extensive preliminary measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If B0 field mapping is determined by making MR measurements at several different pulse times, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent performs B0 field mapping measurements during the initial scout image acquisition phase, before the main diagnostic imaging sequence. This preliminary action captures B0 inhomogeneity data that can be applied to subsequent images, eliminating the need for separate time-consuming B0 mapping measurements for each diagnostic sequence.
Solution Approach 2:
The scout image acquisition serves multiple functions: it provides anatomical overview for localization, enables B0 field mapping for shimming, and establishes reference for motion correction. By making the scout image multi-functional, the patent eliminates the need for separate dedicated B0 mapping sequences.
2Measurement precision
If B0 map is acquired before subject movement, then measurement precision is improved, but adaptability worsens due to subject motion
Solution Approach 1:
The patent uses the initially acquired B0 map as a reference and compares it with data from subsequent scout images to detect subject motion. Based on this feedback, the system updates the B0 field mapping to reflect current subject position, maintaining accuracy despite movement between acquisitions.
Solution Approach 2:
The patent transforms the static B0 map acquired at initial time into a dynamic system that can adapt to subject motion. By periodically updating the B0 mapping using subsequent scout images and motion detection, the system maintains B0 field accuracy throughout the imaging session despite subject movement.
3Measurement precision
If detailed diagnostic image is used for B0 estimation, then measurement precision is improved for local region, but loss of information increases regarding overall anatomical distortion
Solution Approach 1:
The patent performs B0 field mapping using the scout image that covers the entire field of view before acquiring detailed diagnostic images of specific regions. This preliminary full-field B0 mapping captures overall anatomical distortion patterns that would be lost if only local region images were used.
Solution Approach 2:
The patent transitions from local 2D regional imaging to comprehensive 3D full-field B0 mapping by utilizing the scout image's large field of view. This dimensional expansion ensures that B0 inhomogeneities from anatomical structures throughout the entire imaging volume are captured, not just in the specific diagnostic region.
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 time required for B0 field mapping and improves the accuracy of MRI image reconstruction by considering larger anatomical regions and subject movement, leading to enhanced image quality and reduced artifacts.
Implementation Method 1
Magnetic Resonance Imaging (MRI) scanners use a large static magnetic field to align the nuclear spins of atoms
Data Source
AI summary
Disclosed herein is a medical system (100, 300, 500) comprising a memory (110) storing machine executable instructions (120) and a B0 field estimation module (126); and a computational system (106). Execution of the machine executable instructions causes the computational system to receive (200) an initial magnetic resonance image (122) that comprises a magnitude component and is descriptive of a first region (326) of interest of a subject (118). Execution of the machine executable instructions further causes the computational system to perform at least one iteration of the following: receive (202) subsequent k-space data (124) descriptive of subsequent region of interest (328) of the subject; calculate (204) an estimated B0 field mapping (128) for the subsequent region of interest from the initial magnetic resonance image by inputting the initial magnetic resonance image into the B0 field estimation module; and reconstruct (206) a corrected magnetic resonance image (130) from the subsequent k-space data and the estimated B0 field mapping.