Gradient-Echo MRI Motion Sampling During RF Dead Time
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing MRI methods, such as SAMER, prolong acquisition times due to the need for additional motion guidance lines, which are not feasible in steady-state sequences like T2* GRE, and result in increased susceptibility to patient motion, especially in long TE protocols like SWI, degrading image quality.
Innovation Solution
A gradient-echo imaging protocol that inserts additional gradient echoes during the dead-time between RF excitations to acquire motion guidance lines, allowing for rapid estimation of motion parameters without extending scan time, particularly in protocols like SWI, using a low-resolution scout image for reference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional motion guidance lines are acquired using conventional MRI methods, then motion parameter estimation is improved, but acquisition time is prolonged
Solution Approach 1:
The patent acquires motion guidance lines continuously during the dead-time intervals between RF excitations in the main imaging sequence, rather than adding separate acquisition blocks. This allows motion parameter estimation to proceed without interrupting or extending the primary imaging timeline, maintaining continuous useful action throughout the scan.
Solution Approach 2:
The patent implements periodic acquisition of motion guidance lines at regular intervals during the imaging sequence, utilizing the periodic dead-time intervals between RF excitations. This periodic sampling provides sufficient temporal resolution for motion estimation while maintaining the overall periodic structure of the imaging sequence.
2Speed
If additional gradient echoes are inserted to acquire motion guidance lines, then temporal resolution of motion estimation is improved, but sequence complexity increases
Solution Approach 1:
The patent dynamically adjusts the gradient waveform within the dead-time interval to generate additional gradient echoes for motion guidance line acquisition. The gradient sequence is made flexible and adaptive, allowing rapid switching between imaging and motion guidance acquisition modes without requiring separate hardware or fixed sequence structures.
Solution Approach 2:
The gradient system performs multiple functions: it generates both the primary imaging gradients and the additional motion guidance gradients within the same hardware and time framework. The dead-time intervals are universally utilized for dual purposes - maintaining RF excitation timing while inserting motion-sensitive gradient moments.
3Reliability
If motion guidance lines are acquired in steady-state sequences, then motion correction capability is improved, but susceptibility to patient motion increases
Solution Approach 1:
The patent acquires motion guidance lines preliminarily throughout the imaging sequence at regular intervals, establishing a time-resolved motion model before the full imaging dataset is reconstructed. This preliminary motion information is then used to pre-correct or compensate for motion effects in the main imaging data, reducing the impact of patient motion on final image quality.
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 efficiently estimates motion parameters with high temporal resolution, reducing computational cost and scan time, while maintaining image quality and contrast, suitable for retrospective motion correction in protocols like SWI.
Implementation Method 1
A gradient-echo imaging protocol that inserts additional gradient echoes during the dead-time between RF excitations to acquire motion guidance lines
Implementation Method 2
k-space is sampled during the imaging protocol by using RF excitations followed by an echo time resulting in a gradient echo
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to method for acquiring a magnetic resonance image dataset of a field-of-view (S) using a gradient-echo imaging protocol. The method comprises acquiring additional k-space lines (4) within a central region (16) of k-space at intervals throughout the imaging protocol, the additional k-space lines (4) being used for estimating motion parameters of the field-of-view. The imaging protocol has been amended by inserting additional gradient blips (26) after at least some of the RF excitations (22), such that at least one additional gradient echo (25) is generated, allowing the acquisition of at least one additional k-space (4) line during one echo time.