Angular Elliptic Centric View Ordering for MR Imaging
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Solution Overview
Problem
Existing MR imaging techniques face challenges in minimizing eddy current induced artifacts and optimizing contrast, particularly in high-frequency regions of k-space, due to large gradient waveforms and complex acquisition orders.
Innovation Solution
An angular elliptic centric view ordering scheme is implemented, which segments the ky-kz plane into annular segments, defines view ordering based on polar angles, and acquires MR data to reduce gradient polarity switches and total k-space path length, thereby minimizing eddy current effects and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If elliptic centric view ordering is used to acquire central k-space quickly, then contrast is improved, but eddy current artifacts increase due to large gradient jumps in high-frequency regions
Solution Approach 1:
The patent divides k-space into multiple concentric annular segments (first, second, third segments) based on distance from the center. Each segment is acquired separately with optimized view ordering, allowing different acquisition strategies for different spatial frequencies while maintaining overall contrast quality and reducing gradient jumps within each segment.
Solution Approach 2:
The patent applies different view ordering strategies to different regions of k-space. Central regions use one ordering approach while outer regions use another, optimizing each region's acquisition characteristics. This local optimization reduces gradient polarity switches in outer regions without compromising central region contrast.
2Ease of operation
If purely index-based cartesian spiral view ordering is used, then acquisition is simple, but it is only suitable for applications with similar field of view in phase encode directions
Solution Approach 1:
The patent introduces ellipticity parameter (ratio of phase encode directions) as a controllable variable. The view ordering scheme adapts to different ellipticity values, allowing the same basic approach to work for various field of view ratios by adjusting the elliptical geometry parameters rather than requiring completely different acquisition schemes.
3Object-affected harmful factors
If random acquisition is used in central k-space region, then artifacts are reduced, but uncertainty is introduced in the most important region
Solution Approach 1:
Instead of using random ordering to reduce artifacts, the patent applies deterministic angular elliptic centric ordering that systematically progresses through k-space segments. This inverted approach achieves artifact reduction through controlled, predictable gradient transitions rather than randomness, maintaining reliability while still minimizing artifacts.
Data Source
AI summary
A method of magnetic resonance (MR) imaging includes segmenting a ky-kz plane comprising a plurality of encoding points into a plurality of annular segments. For each annular segment, a view ordering is defined based on a polar angle associated with each encoding point contained within the annular segment. MR data is acquired for the plurality of encoding points based on the view ordering for each annular segment and at least one MR image is generated using the acquired MR data.