MRI Gradient Coil Phase Distortion Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional magnetic resonance imaging (MRI) systems face phase distortion issues due to transient responses from gradient coils, particularly in radial scanning, which affect the accuracy of acquired magnetic resonance signals and lead to artifacts in image reconstruction.
Innovation Solution
The MRI apparatus employs a sequence control circuitry to perform first and second scanning operations in opposite radial directions, generating correction coefficients to minimize differences between images formed from these scans, thereby correcting for transient response characteristics and reducing phase distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radial scanning is used to acquire magnetic resonance signals, then robustness against subject movements is improved, but phase distortion occurs due to transient response from gradient coils
Solution Approach 1:
The patent applies preliminary action by performing pre-scanning to measure transient response characteristics before actual image acquisition. The system characterizes the gradient coil's transient response in advance and uses this information to correct phase distortion during radial scanning, thereby maintaining both movement robustness and phase accuracy.
Solution Approach 2:
The patent implements feedback by using the measured transient response characteristics to generate correction coefficients that are applied during signal processing. The system continuously refines the correction based on the relationship between applied gradient waveforms and actual measured phase distortions, improving measurement precision while maintaining radial scanning benefits.
2Measurement precision
If pre-scanning is performed to correct phase distortion, then measurement precision is improved, but imaging time increases
Solution Approach 1:
The patent applies partial action by performing pre-scanning only in necessary directions and using the measured transient response characteristics efficiently. Instead of exhaustive pre-scanning, the system performs minimal necessary measurements to capture gradient coil behavior and applies corrections only where phase distortion occurs in radial scanning.
Solution Approach 2:
The patent changes parameters by optimizing the pre-scanning configuration to reduce measurement time while maintaining correction accuracy. The system adjusts pre-scan parameters such as scanning directions and signal sampling strategies to achieve adequate phase distortion characterization with minimal time loss.
3Measurement precision
If calibration of phase distortion is performed during installation, then measurement precision is improved, but device complexity and setup time increase
Solution Approach 1:
The patent applies self-service by enabling the MRI system to automatically characterize its own gradient coil transient response through pre-scanning. The system performs self-calibration without requiring external calibration equipment or complex manual procedures, reducing device complexity while maintaining measurement precision through automated transient response measurement and correction coefficient generation.
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 approach allows for self-calibration of phase distortion within the imaging process, eliminating the need for pre-scanning and enhancing image quality by reducing artifacts caused by transient responses, especially in radial scanning.
Implementation Method 1
A readout gradient magnetic field needs to be applied to a gradient coil
Implementation Method 2
a phase of an acquired magnetic resonance signal (a phase of a nuclear magnetization of spin) may be distorted
Data Source
AI summary
According to one embodiment, an MRI apparatus includes sequence control circuitry that performs first scanning and second scanning along mutually opposite radial directions in k-space, crossing over a k-space origin, and performs third scanning, and processing circuitry that generates first and second projection images by respectively applying a one-dimensional Fourier transform for the directions to first and second MR signals respectively acquired by the first and second scanning, determines correction coefficients related to transient response characteristics of a readout gradient magnetic field by a calculating process to reduce a difference between the first and second projection images, and generates a corrected image in which the transient response characteristics are corrected using the correction coefficients and MR signals acquired by the third scanning.