Magnetic Resonance Calibration Data Generation for Phase Error Correction
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Solution Overview
Problem
Parallel acquisition techniques in magnetic resonance imaging suffer from phase errors leading to artifacts, such as N/2 ghost artifacts, which are not effectively corrected, impairing the quality of measurement data.
Innovation Solution
A method is developed to create calibration data for undersampled measurement data by recording multiple measurement data sets, creating phase images, determining homogeneity values, and using these values to generate a complete calibration data set, which optimally selects measurement data sets to exclude phase-corrupted data, thereby improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If parallel acquisition techniques are used to accelerate measurement, then productivity is improved, but measurement precision deteriorates due to phase errors and artifacts
Solution Approach 1:
The patent applies preliminary action by recording multiple measurement data sets (first, second, and third data sets) before final image reconstruction. These preliminary measurements include fully sampled reference data and partially sampled data with different phase encoding steps. The calibration data is calculated in advance from these preliminary measurements to correct phase errors, allowing the final accelerated measurement to achieve both high speed and high precision without compromising image quality.
2Loss of time
If undersampled measurement data is used to reduce measurement time, then loss of time is reduced, but measurement precision deteriorates due to insufficient sampling
Solution Approach 1:
The patent uses calibration data as an intermediary element that bridges the gap between undersampled measurement data and complete image reconstruction. The calibration data, derived from fully sampled reference measurements, serves as a mediator that enables accurate reconstruction from accelerated undersampled data. This intermediary calibration information allows the system to achieve complete sampling accuracy without actually performing complete sampling, thus reducing measurement time while maintaining precision.
3Measurement precision
If multiple measurement data sets are recorded to create calibration data, then measurement precision is improved, but productivity decreases due to increased measurement time
Solution Approach 1:
The patent applies partial action by recording a specific number of measurement data sets (exactly R data sets where R is the acceleration factor) rather than requiring complete exhaustive sampling. This partial sampling strategy, combined with the calibration approach, provides sufficient information for accurate calibration without the overhead of recording all possible data sets. The method achieves the necessary calibration precision with a optimized subset of measurements, balancing accuracy and efficiency.
Data Source
AI summary
Calibration data is generated for completing undersampled measurement data acquired via a magnetic resonance system. This includes recording N measurement data sets using an acquisition scheme, and undersampling the k-space with an acceleration factor R, with N being greater than or equal to R, and the N measurement data sets together scanning the k-space completely. Phase images are generated from the N recorded measurement data sets, at least one homogeneity value of the created phase images is determined, and a complete calibration data set is generated based upon the recorded measurement data sets, taking into account the at least one homogeneity value. Thus, it is possible to determine which measurement data sets are subject to undesired phase errors, the measurement data sets used for the creation of the calibration data sets can be selected optimally, and input of the detected phase errors into the calibration data sets can be avoided.