Zero Echo Time MR Imaging Spoke Selection
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Solution Overview
Problem
Current self-refocusing Zero Echo Time (ZTE) imaging techniques require a high number of non-uniformly distributed radial k-space spokes to sample a spherical k-space volume, leading to unnecessary oversampling and increased acoustic noise during MR imaging.
Innovation Solution
A method is developed to specify a set of radial k-space spokes that cover a spherical k-space volume efficiently, selecting subsets to form closed trajectories and minimize acoustic noise through an optimized cost function, allowing for silent ZTE imaging by acquiring gradient echo signals and reconstructing MR images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high number of radial k-space spokes are used to sample a spherical k-space volume, then the coverage of k-space is improved, but the distribution becomes non-uniform leading to oversampling and increased acoustic noise
Solution Approach 1:
The patent changes the parameter of spoke distribution from non-uniform to uniform by optimizing the selection and arrangement of radial k-space spokes. This uniform distribution maintains complete k-space coverage while reducing the total number of spokes required, thereby decreasing acoustic noise generation during the imaging process
Solution Approach 2:
The patent extracts and removes the redundant oversampled spokes from the k-space sampling process. By identifying and eliminating these unnecessary spokes while maintaining adequate coverage, the method reduces the number of gradient switchings and associated acoustic noise without compromising image quality
2Measurement precision
If more radial k-space spokes are acquired, then the signal-to-noise ratio should improve, but the acquisition time and processing complexity increase
Solution Approach 1:
The patent optimizes the spoke selection parameters to achieve a uniform distribution that maintains adequate signal-to-noise ratio with fewer spokes. By changing from a high-number non-uniform sampling scheme to an optimized uniform sampling scheme, the acquisition time is reduced while preserving essential signal quality
3Object-generated harmful factors
If the number of spokes is reduced, then acoustic noise is minimized, but the uniformity of spoke distribution must be optimized to maintain imaging quality
Solution Approach 1:
The patent systematically optimizes the distribution parameters of radial k-space spokes to achieve uniform spacing. This optimized uniform distribution allows for reduced spoke numbers while maintaining stable and consistent sampling coverage across the spherical k-space volume, ensuring imaging quality is preserved
Solution Approach 2:
The patent performs preliminary optimization of spoke selection and arrangement before the actual imaging acquisition. By pre-calculating the optimal uniform distribution pattern, the method ensures that the subsequent imaging process uses the most efficient spoke configuration, minimizing noise while maintaining quality
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 reduces the number of spokes required, enhances signal-to-noise ratio by achieving a more uniform distribution of spokes, and minimizes acoustic noise, thereby improving the efficiency and quality of MR imaging.
Implementation Method 1
at least one main magnet coil for generating a uniform steady magnetic field within an examination volume
Implementation Method 2
at least one RF coil for generating RF pulses within the examination volume and/or for receiving MR signals from a body of a patient positioned in the examination volume
Implementation Method 3
a number of gradient coils for generating switched magnetic field gradients in different spatial directions within the examination volume
Implementation Method 4
utilize the interaction between magnetic fields and nuclear spins in order to form two-dimensional or three-dimensional images
Data Source
AI summary
The invention relates to a method of MR imaging of an object positioned in an examination volume of a MR device (1). It is an object of the invention to enable efficient silent ZTE imaging with self-refocusing. The method of the invention comprises the steps of:—specification of a set of radial k-space spokes to cover a spherical k-space volume;—selection of subsets of a predetermined number of spokes from the specified set so that the concatenation of the spokes contained in each of the subsets forms a closed trajectory in k-space, wherein the selection of the subsets involves optimizing a cost function;—subjecting the object (10) to a zero echo time imaging sequence, wherein each of the subsets of spokes is acquired as a sequence of gradient echo signals; and—reconstructing an MR image from the acquired spokes. Moreover, the invention relates to a MR device and to a computer program for a MR device.