Segmented MRI Reordering With Alternating K-Space Acquisition
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Solution Overview
Problem
Existing methods for reordering segmented MRI pulse sequences, such as interleaved and continuous reordering, suffer from motion-induced artifacts like ghosting and smearing, particularly in high-resolution LGE images, which are unsatisfactorily addressed by current workarounds.
Innovation Solution
A novel reordering scheme, partially reversed continuous (PRC) reordering, combined with a dummy segment (DUS) prior to data collection, creates a smoother modulation function across k-space, reducing non-motion-related artifacts while maintaining motion robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If interleaved or continuous reordering is used for segmented MRI pulse sequences, then data acquisition can be completed in multiple segments, but motion-induced artifacts such as ghosting and smearing occur in the reconstructed images
Solution Approach 1:
The patent applies reverse reordering by acquiring k-space lines in alternating forward and reverse directions for consecutive segments. Specifically, odd-numbered segments acquire lines from low to high k-space indices while even-numbered segments acquire lines from high to low indices, then reorders them sequentially during reconstruction. This inversion approach eliminates the monotonic temporal evolution of modulation functions that causes ghosting artifacts, while maintaining the segmented acquisition structure for time efficiency.
2Productivity
If segmented MRI pulse sequences are used to reduce scan time, then productivity increases, but motion artifacts and ghosting worsen
Solution Approach 1:
The reverse reordering technique alternates the acquisition direction of k-space lines between consecutive segments, with odd segments scanning from low to high indices and even segments scanning from high to low indices. This creates opposing modulation patterns that cancel out motion-induced artifacts during reconstruction, maintaining image consistency across segmented acquisitions while preserving scan efficiency.
Solution Approach 2:
The patent modifies the acquisition parameter by changing the direction of k-space line traversal between segments. Instead of always acquiring in the same direction, the system toggles between forward and reverse directions, which transforms the temporal modulation characteristics and eliminates the systematic artifacts that would otherwise accumulate across segments.
3Ease of manufacture
If conventional reordering methods are used, then data can be acquired in contiguous blocks, but non-motion-related artifacts persist due to modulation discontinuities
Solution Approach 1:
By reversing the acquisition direction for even-numbered segments, the patent creates continuous modulation functions across segment boundaries. The reverse scanning compensates for the temporal discontinuities that would otherwise occur when switching between segments, eliminating non-motion-related artifacts while maintaining the simplicity of contiguous block acquisition.
Data Source
AI summary
A method for reordering a segmented MRI pulse sequence includes synchronizing to a physiologic signal of a heart or vessel, to a respiratory signal, or to an external trigger source, and acquiring a plurality of data collecting segments as a contiguous block in a phase encoding direction such that lines of the plurality of data collecting segments are alternately acquired in a forward direction and a reverse direction for each consecutive data collecting segment.