Radial MR Pulse Sequence Optimization via Sectional Gradient Control
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Solution Overview
Problem
Conventional magnetic resonance imaging with radial k-space sampling is limited by strict timing and hardware constraints, leading to suboptimal imaging parameters such as long repetition times and echo times, which restricts image quality and resolution.
Innovation Solution
The method involves determining gradient amplitudes and increases on logical axes for individual sections of k-space based on their orientation and global maximum values, allowing for section-by-section adaptation to maximize gradient values, thereby reducing repetition times and echo times, and optimizing pulse sequences for faster imaging and improved signal/noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gradient strengths are increased to reduce imaging time, then imaging speed improves, but hardware load and energy consumption increase beyond maximum limits
Solution Approach 1:
The patent divides k-space into multiple sections and processes them separately with different gradient parameters. Each section can be optimized independently, allowing faster imaging overall while keeping individual gradient pulses within hardware limits, thus resolving the contradiction between imaging speed and energy consumption.
Solution Approach 2:
The patent dynamically adjusts gradient amplitudes and slew rates based on the specific section of k-space being sampled. By adapting gradient parameters to each section's requirements rather than using fixed maximum values, the system achieves faster imaging where possible while staying within hardware constraints, balancing productivity and energy use.
2Loss of time
If gradient slew rates are increased to shorten pulse sequence duration, then total examination time reduces, but hardware demands and risk of exceeding maximum load increase
Solution Approach 1:
By segmenting k-space sampling into multiple sections with different gradient parameters, the patent avoids the need for uniformly high slew rates throughout the entire sequence. This reduces peak hardware demands and improves reliability while still achieving shorter total examination time through optimized section-by-section sampling.
Solution Approach 2:
The patent changes gradient parameters (amplitude and slew rate) dynamically based on the current k-space section being sampled. This adaptive parameter adjustment allows the system to achieve faster imaging overall while keeping individual gradient pulses within safe hardware limits, thus reducing examination time without compromising hardware reliability.
3Device complexity
If uniform gradient parameters are used for all k-space sections, then pulse sequence design is simplified, but imaging parameters such as repetition time and echo time are suboptimal
Solution Approach 1:
The patent segments k-space into multiple sections, each with optimized gradient parameters. This segmentation enables tailored optimization of repetition time and echo time for different k-space regions, significantly improving imaging efficiency despite the increased complexity of pulse sequence design. The structured approach to segmentation makes the complexity manageable.
Solution Approach 2:
The patent implements parameter changes by adjusting gradient amplitudes and slew rates according to the specific requirements of each k-space section. This allows optimization of imaging parameters like repetition time and echo time for each section, improving overall imaging efficiency while maintaining a systematic and manageable level of design complexity.
4Speed
If maximum gradient values are applied throughout the entire k-space sampling, then imaging speed maximizes, but hardware constraints are exceeded and image quality deteriorates
Solution Approach 1:
By dividing k-space into sections with different gradient parameter requirements, the patent applies maximum gradient values only where necessary rather than uniformly across all sections. This maintains high data acquisition speed in critical regions while avoiding hardware overload and image artifacts in other regions, thus preserving image quality.
Solution Approach 2:
The patent dynamically changes gradient parameters based on the specific section of k-space being sampled. This allows maximum gradient values to be applied selectively to achieve high acquisition speed where needed, while using reduced gradient values in other sections to prevent hardware constraints from being exceeded and to maintain image 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 enables shorter repetition times and echo times, facilitating faster imaging, higher signal strengths, and improved resolution, while adhering to hardware limitations, particularly beneficial for dynamic imaging and live processes.
Implementation Method 1
a magnetic field gradient is applied by a gradient system of the scanner
Implementation Method 2
Radio-frequency excitation signals (RF signals) are then radiated by a radio-frequency transmitting system using suitable antennas in order to tip the nuclear spins of specific atoms
Implementation Method 3
the body to be examined is usually exposed to a relatively high basic magnetic field, e.g. 1, 3, 5 or 7 Tesla, by a basic field magnet in the scanner of the apparatus
Data Source
AI summary
In a method, magnetic resonance apparatus, and pulse optimization computer for determining a pulse sequence for radial sampling of k-space in magnetic resonance imaging, the amplitudes and the increases with respect to time of readout gradients and phase gradients for individual sections of k-space are determined depending on an orientation of the respective section in k-space and depending on global maximum values of the amplitudes and the increases of the gradients on the physical axes.