Gradient Delay Time Correction in MRI k-Space
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Solution Overview
Problem
Magnetic resonance imaging (MRI) data suffers from image quality inconsistencies and artifacts due to gradient delay effects, particularly in non-Cartesian sampling models where delay effects cause k-space shifts, leading to ghosting and local signal obliterations.
Innovation Solution
A computer-implemented method for gradient delay time correction in MRI data using a magnetic resonance device, which involves recording calibration data in a resolved manner in partition direction, determining partition-dependent correction data, and applying these corrections to the MRI data to compensate for delay effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-Cartesian sampling models with linear recording trajectories in different readout directions are used, then susceptibility to movement and flow artifacts is reduced, but gradient delay effects cause k-space shifts leading to image quality inconsistencies and artifacts
Solution Approach 1:
The patent applies preliminary action by performing a calibration measurement before the actual magnetic resonance data acquisition. During this calibration step, correction data is determined that characterizes the gradient delay effects for different readout directions. This pre-determined correction data is then applied to the subsequent data acquisition, allowing the system to operate in non-Cartesian sampling modes while compensating for the gradient delay artifacts that would otherwise degrade image quality.
2Quantity of substance
If gradient pulses with opposing polarities are used in contra-oriented recording trajectories, then sampling coverage is improved, but delay effects cause varying k-space shifts depending on readout direction
Solution Approach 1:
The patent applies local quality by determining separate correction data for different readout directions rather than using a single global correction. The calibration measurement evaluates the delay effects specifically for each readout direction used in the contra-oriented recording trajectories. This direction-specific correction data is then applied locally to compensate for the varying k-space shifts that occur in different directions, allowing the system to maintain sampling coverage while achieving consistency across different readout orientations.
3Measurement precision
If calibration data is recorded to determine correction values for gradient delay effects, then correction accuracy is improved, but measurement time and complexity increase
Solution Approach 1:
The patent applies universality by designing a calibration measurement that determines correction data applicable to all readout directions used in the magnetic resonance data acquisition. Rather than performing separate calibrations for each direction or trajectory, the calibration process establishes a set of correction values that can be universally applied across the entire non-Cartesian sampling scheme. This multi-functional correction data set reduces the overall calibration time while maintaining accuracy across different readout directions.
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 method significantly reduces spatially varying eddy current effects, thereby improving the image quality of MRI data by addressing the partition-dependent nature of gradient delay artifacts.
Implementation Method 1
Eddy currents that are generated by gradient pulses can result in temporally and spatially variable field interferences in magnetic resonance devices
Implementation Method 2
calibration data is recorded, which describes readout-direction-dependent shifts caused by delay effects of measurement points, in particular, sampled k-space sections, in the k-space
Implementation Method 3
correction data is determined by evaluating the calibration data, and the magnetic resonance data is corrected on the basis of the correction data in order to compensate for the delay effects
Data Source
AI summary
A computer-implemented method for gradient delay time correction of MR data using an MR device, wherein the magnetic resonance data is recorded using a three-dimensional recording technique with linear recording trajectories which are oriented in different readout directions of a readout plane that is perpendicular to a partition direction. The method includes: in a calibration measurement using the magnetic resonance device, recording calibration data which describes readout-direction-dependent shifts, caused by delay effects, of measurement points in the k-space; determining correction data by evaluating the calibration data; correcting the MR data based on the correction data in order to compensate for the delay effects, wherein the calibration data, which covers a coverage region in partition direction is recorded in a resolved manner, and the correction data is determined and applied in a manner that is dependent on partition direction.