MRI Readout Gradient Field Error Compensation
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Solution Overview
Problem
In UTE measurements, the non-linear rising of the readout gradient magnetic field leads to errors in gridding due to deviations from theoretical values, resulting in distorted image quality and inability to accurately calculate the peak position in k-space coordinates.
Innovation Solution
An MRI apparatus with a correction value calculating unit that measures the difference between set and actual readout gradient magnetic field values, allowing for correction of echo data or the readout gradient magnetic field, enabling accurate gridding and improved image reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If gridding is performed using calculated gradient magnetic field values, then image reconstruction becomes possible, but image quality deteriorates due to errors from deviation between calculated and actual gradient values
Solution Approach 1:
The patent applies preliminary action by performing a prescan measurement before actual imaging to obtain the actual gradient magnetic field values. These measured values are then used to correct the gradient field parameters for subsequent gridding operations, ensuring both image reconstruction capability and high image quality by eliminating deviation errors in advance
Solution Approach 2:
The patent implements feedback by measuring the actual gradient magnetic field values through prescan, comparing them with calculated values, and using the difference (correction value) to adjust the gridding parameters. This closed-loop approach ensures that the gridding process uses accurate gradient field information, resolving the contradiction between reconstruction capability and image quality
2Measurement precision
If correction value calculating unit is added to measure gradient field deviation, then gridding accuracy improves, but device complexity increases
Solution Approach 1:
The patent applies universality by making the correction value calculating unit a software or processing function integrated into the existing MRI control system, rather than a separate physical device. This multi-functional approach allows the same system to perform both imaging and gradient field correction, improving gridding accuracy without significantly increasing device complexity
Solution Approach 2:
The system performs self-service by automatically measuring gradient field deviations and calculating correction values without requiring external intervention or additional complex hardware. The correction process is integrated into the normal imaging workflow, achieving high measurement precision while maintaining simplicity through automated self-correction
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 correction of gridding parameters and readout gradient magnetic field start times results in high-quality images with no distortion or contrast changes, effectively addressing the errors caused by deviations in gradient magnetic field applications.
Implementation Method 1
a readout gradient magnetic field generator that generates a readout gradient magnetic field for reading out the magnetic resonance signal
Implementation Method 2
an imaging method of measuring a magnetic resonance signal from the rise time of a readout gradient magnetic field (nonlinear measurement)
Data Source
AI summary
In nonlinear measurement in which a dephasing readout gradient magnetic field is not used, a positional shift of the k space data, which is caused by a difference between a readout gradient magnetic field actually applied and the calculated value, and a deterioration in the image quality resulting therefrom are reduced. In order to do so, in the invention, when executing an imaging pulse sequence including a nonlinear measurement which does not use a dephasing gradient magnetic field, a prescan sequence is executed and a correction value for correcting the shift of the readout gradient magnetic field from the set value is calculated from the data acquired in the prescan. When gridding the data acquired in the imaging pulse sequence, a parameter value of the gridding is corrected using the correction value to perform the gridding.