Radial MRI Spoke Trajectory for Non-Circular Acquisition Areas
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Radial scanning methods for magnetic resonance imaging (MRI) face severe undersampling issues when dealing with non-circular acquisition areas, particularly in the direction of the larger dimension, and existing golden angle trajectories are not effective for non-circular shapes.
Innovation Solution
The method involves selecting angles for successive spokes in radial scanning using a golden angle trajectory, ensuring uniform scanning by associating acquisition positions with first angles based on a comparison data set, allowing for an angle-dependent target density in k-space that describes the desired non-circular acquisition area, thereby reducing undersampling artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If radial scanning is used for subjects with non-circular dimensions, then the acquisition area covers the entire subject, but severe undersampling occurs in the direction of the larger dimension
Solution Approach 1:
The patent applies local quality by varying the spoke density according to the local geometry of the subject. For non-circular acquisition areas, the spoke density is adapted locally - higher density in directions where the subject extends further - to maintain uniform sampling coverage across the entire non-circular area without severe undersampling in any direction.
Solution Approach 2:
The patent changes the parameter of spoke angular distribution from uniform to non-uniform based on the acquisition area shape. By adjusting the angular spacing of spokes as a function of angle and subject geometry, the method optimizes sampling uniformity for non-circular areas, transforming the sampling pattern to match the subject's dimensional characteristics.
2Measurement precision
If golden angle trajectory is used for circular acquisition areas, then uniform scanning is achieved in subsets of successive spokes, but the trajectory is not effective for non-circular acquisition areas
Solution Approach 1:
The patent makes the spoke angular positions dynamic rather than fixed, adjusting them based on the acquisition order and the specific non-circular geometry. The angular positions are determined adaptively for each acquisition step to maintain uniform sampling properties even when the acquisition area deviates from circular symmetry, extending the golden angle concept to non-circular cases.
Solution Approach 2:
The patent applies asymmetry by abandoning the symmetric uniform angular distribution of the traditional golden angle trajectory and instead using asymmetric angular positions that are optimized for the specific non-circular acquisition area shape. This asymmetric distribution maintains the beneficial property of uniform sampling in subsets while adapting to the asymmetric geometry.
3Ease of operation
If equally distributed spokes are used over 360°, then a circular acquisition area results, but non-circular acquisition areas require non-constant spoke density
Solution Approach 1:
The patent changes the parameter of spoke angular distribution from constant (equally distributed) to variable (non-constant density), where the angular spacing between spokes is adjusted as a function of the angle and the desired non-circular acquisition area shape. This allows the system to maintain simple operation while achieving versatile adaptation to different geometries.
Data Source
AI summary
Method to acquire a magnetic resonance data set of an acquisition area (5) in a subject (O) via radial scanning along a fixed number of spokes (6) respectively described by a first angle in k-space, wherein the acquisition area (5) deviates in positional space from a circular shape in a shape that can be described by the set of first angles; wherein the acquisition of the spokes (6) takes place according to an acquisition order; wherein an acquisition position of the acquisition order is associated with each first angle under consideration of a comparison data set of the fixed number of second angles (in which second angles of successive acquisition positions differ by a golden angle) such that, for a first angle of each acquisition position, the spatially adjacent first angles have the same acquisition positions as the second angles spatially adjacent to a second angle of the acquisition position.