MRI k-space Blade Ordering for Multi-shot Artifact Reduction
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Solution Overview
Problem
Conventional 3D MRI view-ordering schemes are not compatible with multi-shot acquisitions, making it difficult to encode desirable views into the center of k-space, especially when signal levels vary between shots, which is problematic for uniform parallel imaging and variable density k-space sampling schemes.
Innovation Solution
A method that partitions the ky-kz plane into blades, allowing each shot to acquire views based on a defined blade ordering and intra-shot view ordering, ensuring that preferred views are encoded near the center of k-space while varying signal levels are managed across shots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional 3D MRI view-ordering schemes are used, then the acquisition can be completed, but the desirable views cannot be properly encoded into the center of k-space when signal levels vary between shots
Solution Approach 1:
The patent segments the k-space acquisition into multiple shots, with each shot acquiring a specific portion of k-space data. The view-ordering is divided into intra-shot ordering (within each shot) and inter-shot ordering (across multiple shots), allowing independent optimization of each segment while maintaining overall coherence
Solution Approach 2:
The patent introduces dynamic view-ordering strategies that adapt to varying signal levels between shots. The ordering scheme is modified based on the transient signal characteristics of each shot, allowing the system to dynamically adjust which views are acquired in which shots to optimize center k-space encoding
2Productivity
If multi-shot acquisitions are used to reduce scan time, then productivity improves, but conventional view-ordering schemes become incompatible and image quality deteriorates
Solution Approach 1:
The patent performs preliminary planning of the view-ordering scheme before acquisition, determining the optimal assignment of views to shots and the intra-shot ordering sequences in advance. This preliminary configuration ensures that desirable views are pre-assigned to appropriate shots based on expected signal characteristics
Solution Approach 2:
The patent modifies the view-ordering parameters specifically for multi-shot acquisitions, changing the encoding strategy from static conventional schemes to dynamic schemes that account for shot-to-shot signal variations. This includes adjusting phase-encoding step sequences and timing parameters
3Productivity
If uniform parallel imaging or variable density sampling is used, then acquisition efficiency improves, but the varying signal levels across shots cause artifacts
Solution Approach 1:
The patent incorporates feedback mechanisms where the actual signal levels observed during acquisition are used to adjust subsequent view-ordering decisions. This feedback loop allows the system to adapt to real-time signal variations and correct for potential artifact-causing discrepancies
Solution Approach 2:
The patent converts the potentially harmful effect of varying signal levels into a benefit by using the signal variations to guide the view-ordering strategy. Shots with higher signal levels are strategically assigned to acquire specific portions of k-space, turning the variability into an optimization opportunity rather than a source of artifacts
Data Source
AI summary
A multi-shot three-dimensional (3D) magnetic resonance imaging (MRI) data view-ordering strategy for uniform or variable density k-space sampling schemes is presented. The ky-kz plane is partitioned into multiple wedge-shaped “blades” (or radial fan beams). The angular size of individual blades may be adjusted according to the desired number of views for each blade. Each blade includes views near the origin that contain low-frequency information about the imaged object such that views having the most desirable characteristics may be used to fill the central portions of k-space.