Adaptive Water-Fat Shift Alignment in Non-Cartesian MRI for Clearer Images
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Non-Cartesian k-space sampling patterns in magnetic resonance imaging result in varying readout directions, leading to spatial fat-water shifts that cause image blurring and unexpected appearances, making it difficult for radiologists accustomed to Cartesian patterns.
Innovation Solution
A method to control magnetic resonance imaging systems using non-Cartesian k-space sampling by rotating Cartesian patterns for each acquisition to align the effective water-fat shift direction with a chosen direction, adjusting gradient encodings, and applying view angle tilting gradients to minimize spatial shifts and emulate Cartesian-like images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If non-Cartesian k-space sampling patterns are used, then image acquisition speed and efficiency are improved, but spatial fat-water shifts occur in various directions causing image blurring and unexpected appearance
Solution Approach 1:
The patent applies local quality by adjusting the readout bandwidth specifically in directions where fat-water shifts occur, rather than uniformly across all directions. By identifying the dominant shift direction and increasing bandwidth selectively in that direction, the method reduces blurring where it matters most while maintaining efficiency in other directions.
Solution Approach 2:
The patent changes the readout bandwidth parameter adaptively based on the sampling pattern orientation. The bandwidth is increased in directions where fat-water chemical shift causes blurring, and maintained at standard levels in other directions. This dynamic parameter adjustment resolves the contradiction between acquisition speed and image quality.
2Manufacturing precision
If readout bandwidth is increased to reduce fat-water shift blurring, then image quality is improved, but scan time increases
Solution Approach 1:
Instead of increasing readout bandwidth uniformly in all directions (which would increase scan time), the patent applies bandwidth adjustment only in the specific direction where fat-water shifts cause blurring. This localized approach improves image quality without proportionally increasing scan time.
Solution Approach 2:
The patent dynamically adjusts the readout bandwidth parameter based on the sampling pattern and dominant shift direction. By changing bandwidth only when and where needed, the method achieves image quality improvement with minimal impact on scan time.
3Manufacturing precision
If Cartesian k-space sampling patterns are used, then image appearance is consistent and familiar to radiologists, but acquisition efficiency is reduced compared to non-Cartesian patterns
Solution Approach 1:
The patent modifies the readout bandwidth parameter in non-Cartesian sampling to compensate for fat-water shifts, making the image appearance more consistent and predictable like Cartesian images, while retaining the acquisition efficiency of non-Cartesian patterns.
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 reduces image blurring and aligns the appearance of non-Cartesian images with Cartesian standards, enhancing readability and quality, particularly for radiologists.
Implementation Method 1
Due to a chemical shift in the NMR signal, fat and water tissue have slightly different resonant frequencies in the readout direction
Implementation Method 2
This excited region is then spatially encoded using magnetic field gradient encoding and phase encoding
Data Source
AI summary
Disclosed herein is a medical system (100, 300) comprising a memory (110) storing machine executable instructions (120). The medical system further comprises a computational system (104). Execution of the machine executable instructions causes the computational system to: receive (200) initial pulse sequence commands (122), wherein the initial pulse sequence commands are configured for controlling a magnetic resonance imaging system (302) to acquire k-space data (332) following a non-Cartesian k-space sampling pattern (604, 604′), wherein the initial pulse sequence commands are configured for controlling the magnetic resonance imaging system to sample the non-Cartesian k-space sampling pattern by repeatedly sampling a Cartesian k-space sampling pattern (126) that is rotated for each acquisition, wherein the non-Cartesian k-space sampling pattern has an effective water-fat shift direction (606, 606′); receive (202) a chosen water-fat shift direction (124); and construct (204) modified pulse sequence commands by rotating the non-Cartesian k-space sampling pattern such that the effective water-fat shift direction is aligned with the water-fat shift direction.