Radial K-Space MRI Acquisition for Eddy-Current Control
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Solution Overview
Problem
Conventional magnetic resonance imaging techniques with ultra-short echo times face challenges such as interference from eddy currents, limited resolution, and inefficient signal acquisition, particularly in 2D and 3D measurements, leading to incomplete data capture and prolonged measurement times.
Innovation Solution
A method involving gradient switching in the slice selection direction and non-slice-selective RF excitation, followed by radial k-space trajectory recording, allows for partitioning of k-space data to enhance 3D imaging with reduced measuring time and improved signal fidelity, using a magnetic resonance system with enhanced gradient control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional UTE sequences are used with gradient switching, then 2D and 3D measurements can be performed, but eddy currents interfere with the measurement and prolong measurement time
Solution Approach 1:
The gradient is switched on before the RF excitation pulse to pre-establish the desired gradient conditions. This preliminary action allows the gradient to be ready before measurement begins, avoiding the need to switch gradients during the measurement and thereby eliminating eddy current interference while maintaining measurement precision.
2Speed
If radial k-space trajectory is used, then ultra-short echo time is achieved, but the raw data must be converted to Cartesian grid requiring regridding
Solution Approach 1:
The patent extracts only the necessary k-space data points along a simplified trajectory that can be directly reconstructed without regridding. By taking out only the essential data points needed for image reconstruction and avoiding the complex radial trajectory, the method achieves ultra-short echo times while eliminating the complex regridding process.
3Loss of time
If point-like k-space sampling is used, then single point imaging is achieved, but resolution is limited
Solution Approach 1:
The patent transitions from single-point sampling to multi-point sampling along a trajectory in k-space. By adding the dimension of trajectory traversal through multiple k-space points rather than sampling only at a single point, the method achieves both ultra-short echo times and improved image resolution simultaneously.
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 enables rapid, robust, and efficient 3D imaging with improved signal-to-noise ratio and reduced measurement duration, focusing on regions of interest while minimizing interference from coil sensitivity variations.
Implementation Method 1
In order to trigger nuclear spin resonances which can be measured as signals, radio-frequency excitation pulses (radio frequency, RF pulses) are radiated into the examination object
Implementation Method 2
For spatial encoding of the measurement data, fast-switched magnetic gradient fields, called gradients for short, are overlaid on the basic magnetic field
Implementation Method 3
An associated MR image can be reconstructed from the k-space matrix occupied by values, for example by means of a multi-dimensional Fourier transform
Data Source
AI summary
In a method for creating an image dataset of a mapping area situated in a measuring volume, k-space corresponding to the mapping area may be read out and image data may be reconstructed based on recorded first and second raw data points of k-space. The reading out of k-space may include: switching a gradient in the slice selection direction and a phase-encoding gradient in at least one further encoding direction, radiating a non-slice-selective radio-frequency (RF) excitation pulse, recording echo signals and storing them as first raw data points along a radial k-space trajectory predefined by the full strength of the phase-encoding gradients (Gp) further switched during recording of the echo signals, and reading out k-space corresponding to the mapping area as second raw data points.