MRI Parallel Imaging Background Sensitivity Estimation
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Solution Overview
Problem
The parallel imaging method in MRI apparatuses generates artifacts due to a drastic decline in sensitivity information at the boundary between the object and background regions, leading to constrained and noisy images.
Innovation Solution
The MRI apparatus and method estimate sensitivity distribution information for the background region using that of the object region and update it across multiple high-frequency receiver coils to suppress noise components in the unfolded images, optimizing the sensitivity distribution matrix to reduce artifacts and improve image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If sensitivity of background region is set to zero or fixed number to reduce artifacts, then noise artifacts are reduced, but sensitivity information declines drastically at boundary causing new artifacts and constrained images
Solution Approach 1:
The patent changes the parameter of sensitivity distribution in the background region from fixed/zero values to estimated values derived from object region sensitivity distribution. This allows the sensitivity information to transition smoothly across the boundary, preventing drastic declines while still suppressing noise artifacts through the estimated sensitivity values.
Solution Approach 2:
The patent copies the sensitivity distribution pattern from the object region and applies it to the background region. By estimating background sensitivity based on object sensitivity patterns, the system preserves the spatial relationship and continuity of sensitivity information across the boundary, avoiding the artificial discontinuities that cause new artifacts.
2Manufacturing precision
If multiple RF coils are used for parallel imaging to improve image quality, then sensitivity distribution can be optimized, but device complexity increases
Solution Approach 1:
The patent makes the sensitivity distribution estimation process universal by using the same estimation method across all coils and regions. The sensitivity distribution information obtained from one coil can be applied to other coils through the estimation process, reducing the need for separate calibration and processing for each coil, thereby managing complexity while maintaining image quality.
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 effectively reduces artifacts in unfolded images, enhancing the quality of MRI images by optimizing sensitivity distribution and maintaining signal-to-noise ratio (SNR) across the image region.
Implementation Method 1
detecting NMR signals generated from an object to be examined
Data Source
AI summary
A magnetic resonance imaging apparatus comprises a plurality of high-frequency reception coils, sensitivity distribution information obtaining means for calculating sensitivity distribution information of each of the high-frequency reception coil, sensitivity distribution storage means for storing the sensitivity distribution information, measuring means for acquiring magnetic resonance signals by thinning out encode steps of a k-space, image reconstructing means for reconstructing images using the magnetic resonance signals, and means for performing unfolding calculation using the sensitivity distribution information and the image, thereby to acquire the unfolded image.The magnetic resonance imaging apparatus further comprises means for estimating the sensitivity distribution information of a background region by using the sensitivity distribution information of an object region, and means for updating the background region by mutually using the sensitivity distribution information of the respective high-frequency receptions coils thereby to suppress noise component contained in the unfolded image.