RF Pulse Correction for MRI Gradient Non-Linearity
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Solution Overview
Problem
Magnetic resonance images often suffer from deformations due to insufficient position encoding caused by deviations in the gradient coil unit's magnetic field, leading to artifacts in the reconstructed images.
Innovation Solution
A computer-implemented method determines an RF transmission pulse for a magnetic resonance scan by using deviation information that characterizes position-dependent deviations from a target state caused by the gradient coil unit, allowing for the correction of these deviations during the scan, thereby reducing artifacts in the images. This method involves providing a deviation information item that maps the non-linearities of the gradient coil unit and using it to adjust the RF transmission pulse in terms of amplitude, phase, and frequency, ensuring accurate position encoding and image reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gradient coil unit is used for position encoding, then magnetic resonance signals can be spatially encoded, but position-dependent deviations from target state cause deformations in reconstructed images
Solution Approach 1:
The patent applies preliminary action by determining a corrected RF transmission pulse before the actual magnetic resonance scan. The method calculates deviation information characterizing position-dependent deviations from the target state, and uses this information to pre-correct the RF transmission pulse parameters (amplitude, phase, frequency) so that when the pulse is applied during scanning, the gradient coil non-linearities are compensated and accurate position encoding is achieved without geometric distortions in the reconstructed images.
2Manufacturing precision
If RF transmission pulse parameters are adjusted to correct gradient non-linearities, then image geometric accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent performs the computationally intensive pulse correction calculation in advance, before the actual scan. The system determines deviation information and calculates the corrected RF transmission pulse parameters (amplitude, phase, frequency adjustments) in a preliminary step, storing this correction data for use during scanning. This approach shifts the computational burden to a pre-processing stage rather than requiring real-time calculations during the scan, thus improving image geometric accuracy without significantly increasing the complexity during the actual scanning operation.
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 effectively reduces deformations and artifacts in magnetic resonance images by accounting for gradient coil non-linearities during the scan, improving image quality and avoiding the need for subsequent corrections during or after image reconstruction.
Implementation Method 1
with the aid of a gradient coil unit of the magnetic resonance apparatus, temporary magnetic field gradients are generated in the imaging region
Implementation Method 2
radio frequency (RF) transmission pulses may be radiated into the examination object with the aid of a transmitting coil arrangement of the magnetic resonance apparatus. By way of the pulses generated, magnetic resonance signals are excited and triggered in the patient
Data Source
AI summary
A method, a magnetic resonance apparatus, and a computer program product are disclosed. In particular, a method is provided for determining an RF transmission pulse for a magnetic resonance scan by a magnetic resonance apparatus including a gradient coil unit. The method includes a provision of a deviation information item, wherein the deviation information item characterizes a position-dependent deviation from a target state, caused by the gradient coil unit, in an imaging region of the magnetic resonance apparatus. The RF transmission pulse is determined taking account of the deviation information item.