Dynamic Field Camera for Spiral Echo Train k-Space Trajectory Correction
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Solution Overview
Problem
Conventional methods for estimating k-space trajectories in spiral echo train imaging are inadequate, as errors introduced by spiral gradients can build up during the echo train, leading to image artifacts and inaccuracies in image reconstruction.
Innovation Solution
A method and system utilizing a dynamic field camera and MRI system to measure k-space values and field dynamics for each echo of a spiral echo pulse train, generating a model of the k-space trajectory to compensate for imperfections and reconstruct accurate images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional k-space measurement techniques are used for spiral echo train imaging, then the measurement process is simple, but errors in k-space trajectory estimation build up during the echo train causing image artifacts
Solution Approach 1:
The patent segments the echo train into individual echoes, measuring and correcting k-space trajectory errors for each echo independently rather than attempting a single global measurement. This is achieved by inserting calibration pulses between echoes and processing each echo's k-space data separately, which prevents error accumulation while maintaining manageable system complexity through modular correction processing.
Solution Approach 2:
The patent implements feedback by measuring actual k-space trajectories using calibration pulses and using these measurements to generate correction factors that are applied to subsequent echo data. The system continuously monitors trajectory deviations and adjusts reconstruction parameters accordingly, creating a closed-loop correction system that maintains high measurement precision throughout the echo train.
2Productivity
If spiral gradients are applied continuously through the echo train, then imaging speed is improved, but phase errors build up and compromise image quality
Solution Approach 1:
The patent applies preliminary calibration pulses before each echo to pre-characterize the gradient waveform and predict resulting phase errors. These preliminary measurements allow the system to prepare correction factors in advance, enabling continuous high-speed spiral imaging while maintaining reliable image quality through proactive rather than reactive error correction.
Solution Approach 2:
The patent dynamically adjusts reconstruction parameters based on measured trajectory deviations. By changing the k-space trajectory model parameters for each echo based on actual measurements, the system maintains accurate image reconstruction even as gradient-induced phase errors accumulate during continuous high-speed imaging.
3Reliability
If respiratory gating or motion compensation is used, then motion artifacts are reduced, but scan time increases and complexity increases
Solution Approach 1:
The patent replaces mechanical motion control methods (respiratory gating, breath-hold techniques) with a field-based correction approach. Instead of physically controlling or timing scans to avoid motion, the system measures actual gradient field deviations and corrects the resulting phase errors in the k-space data, achieving motion robustness through electromagnetic field characterization rather than mechanical constraints.
Solution Approach 2:
The patent introduces calibration pulses as intermediary elements that mediate between the gradient waveform generation and the actual imaging process. These calibration pulses provide intermediate measurements of field deviations that can be used to correct subsequent echo data, serving as a bridge that allows continuous scanning without requiring respiratory gating or complex motion coordination.
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
The approach ensures accurate image reconstruction by isolating and accounting for errors in each echo, resulting in high-quality images even in the presence of motion without respiratory gating or motion compensation.
Implementation Method 1
measuring k-space values and field dynamics corresponding to each echo of a spiral echo pulse train, using a dynamic field camera and a magnetic resonance imaging (MRI) system
Implementation Method 2
errors introduced by the spiral gradients have the potential to build up during the echo train
Data Source
AI summary
In some aspects, the disclosed technology relates to magnetic field monitoring of spiral echo train imaging. In one embodiment, a method for spiral echo train imaging of an area of interest of a subject includes measuring k-space values and field dynamics corresponding to each echo of a spiral echo pulse train, using a dynamic field camera and a magnetic resonance imaging (MRI) system. The dynamic field camera is configured to measure characteristics of fields generated by the MRI system; the characteristics include at least one imperfection associated with the MRI system. The spiral echo pulse train corresponds to a spiral trajectory scan from the MRI system that obtains magnetic resonance imaging data using a pulse sequence which applies spiral gradients in-plane with through-plane phase encoding. The method also includes generating, based on the characteristics of the fields measured by the dynamic field camera and based on the obtained magnetic resonance imaging data, a model of the k-space trajectory corresponding to each echo of the spiral echo pulse train; and, based on the generated model of the k-space trajectory, reconstructing images that correspond to the area of interest and that are compensated for the at least one imperfection associated with the MRI system.