MRI Projection Ordering via Coulomb Repulsion
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Solution Overview
Problem
Conventional MRI systems face challenges in evenly distributing 3D radial projections, leading to issues like signal bunching and varying image quality due to limitations in projection ordering algorithms, particularly for bent and multi-echo trajectories.
Innovation Solution
An iterative approach is employed to order projections by treating end points as point charges on a volume, using Coulomb's law to calculate influences between points, and adjusting their positions to achieve a more uniform distribution in both space and time, facilitating improved sampling in k-space and kt-space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional projection ordering algorithms (e.g., 3D golden means) are used to evenly distribute 3D radial projections, then projection distribution is improved, but the system is limited to single radial projection per TR and cannot handle bent or multi-echo trajectories
Solution Approach 1:
The patent changes the fundamental parameters of the projection ordering approach by transitioning from fixed geometric algorithms to a physics-based Coulomb interaction model. This allows the system to handle variable trajectory types (bent, multi-echo, radial) while maintaining uniform distribution through iterative optimization of projection timestamps rather than fixed geometric patterns
Solution Approach 2:
The Coulomb-based ordering algorithm provides universal applicability across multiple trajectory types (radial, bent, multi-echo) and acquisition schemes (single or multiple projections per TR). The same underlying physics-based principle adapts to different imaging scenarios, making the system multi-functional without requiring separate algorithms for each case
2Productivity
If multi-echo trajectories are used to increase sampling efficiency, then productivity is improved, but signal bunching occurs leading to varying image quality and artifacts
Solution Approach 1:
The patent implements feedback through iterative optimization where the Coulomb interaction energies are calculated and used to adjust projection timestamps. The system continuously evaluates the distribution uniformity (through energy calculations) and refines the ordering until convergence, ensuring that multi-echo trajectories achieve uniform sampling without signal bunching
Solution Approach 2:
The projection ordering transitions from static geometric patterns to dynamic timestamp optimization. The system adaptively adjusts acquisition times based on real-time calculations of Coulomb interactions, allowing the ordering to be optimized specifically for multi-echo trajectories where multiple k-space lines are sampled per TR, thereby preventing signal bunching while maintaining high sampling efficiency
3Speed
If radial projections are acquired quickly to remove cardiac gating requirements, then speed is improved, but projection bunching occurs leading to artifacts and reduced image quality
Solution Approach 1:
The patent changes the optimization parameter from geometric distribution to temporal distribution. By optimizing acquisition timestamps rather than spatial angles, the system maintains fast radial acquisition speeds while preventing temporal bunching of projections that causes artifacts. The Coulomb-based ordering ensures uniform temporal spacing of k-space sampling points
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 method enhances image quality by achieving a more even distribution of projections, reducing artifacts and improving sampling efficiency, allowing for faster and more flexible dynamic imaging applications.
Implementation Method 1
using Coulomb's law to calculate influences between points
Data Source
AI summary
Example apparatus and methods order projections in a 3D MRI acquisition to achieve improved equidistant spacing or to achieve improved adherence to a target distribution. The equidistant or target spacing may exist in k-space and/or in kt-space. In one embodiment, the improved equidistant spacing is a substantially uniform spacing. The substantially uniform spacing may be achieved using a modification of a charge repulsion analysis that treats points of projections that intersect the surface of a 3D volume to be imaged as point charges distributed on the 3D volume. In another embodiment, the target spacing may be uniform, non-uniform, uniform in parts and non-uniform in other parts, and other combinations.