MRI Apparatus Echo Time Segmentation for Spatial Resolution
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Solution Overview
Problem
Conventional MRI techniques face challenges in achieving high spatial and time resolution simultaneously, particularly when imaging tissues with short T2 or T2* relaxation times, due to restrictions in gradient magnetic field switching speed, which limits the intensity of the gradient magnetic field and reduces spatial resolution.
Innovation Solution
The MRI apparatus employs an acquisition function that acquires echo signals at intervals of repetition time (TR) with varying echo times (TE), allowing for high-intensity gradient magnetic fields and improved spatial resolution, while also reducing time differences between TE settings to enhance time resolution, by successively changing TE and applying spoiler gradient magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the gradient magnetic field intensity is increased to improve spatial resolution, then spatial resolution is improved, but the gradient magnetic field switching speed becomes restricted which limits further intensity increases
Solution Approach 1:
The patent segments the data acquisition process into multiple trajectories in k-space, where each trajectory is acquired with a different echo time. This segmentation allows the use of high-intensity gradient magnetic fields for each individual trajectory without requiring rapid switching between different intensity levels, thereby improving spatial resolution while managing the gradient switching speed limitation.
Solution Approach 2:
The patent dynamically adjusts the echo time for each trajectory acquisition, successively changing TE across different trajectories. This dynamic adjustment enables the system to utilize high-intensity gradient magnetic fields effectively for each trajectory while maintaining flexibility in the acquisition process, resolving the contradiction between gradient intensity and switching speed.
2Manufacturing precision
If the echo time difference between measurements is reduced to improve time resolution, then time resolution is enhanced, but the acquisition time increases
Solution Approach 1:
The patent implements continuous acquisition across multiple trajectories with successively changing echo times, eliminating idle time between measurements. By continuously acquiring data with different TEs across different trajectories rather than completing one full acquisition sequence before starting the next, the system reduces the time difference between TE settings while minimizing the increase in total acquisition time.
Solution Approach 2:
The patent distributes measurements across multiple trajectories in k-space rather than using a single trajectory with multiple TEs. This dimensional approach allows simultaneous variation of both trajectory angle and echo time, enabling fine time resolution through small TE differences while maintaining efficient data acquisition across the k-space domain.
3Measurement precision
If multiple echo signals are acquired with different echo times to improve measurement accuracy, then measurement accuracy is improved, but the acquisition time increases
Solution Approach 1:
The patent segments the acquisition of multiple echo signals with different TEs across multiple trajectories, allowing interleaved acquisition of different TE values. This segmentation enables the system to collect data for T2* mapping with high measurement accuracy while distributing the time cost across multiple trajectories rather than concentrating it in a single location, thereby reducing the overall impact on acquisition time.
Solution Approach 2:
The patent employs periodic variation of echo times across successive trajectories, creating a systematic pattern of TE changes. This periodic approach allows efficient sampling of different TE values for accurate T2* measurement while maintaining a regular, predictable acquisition rhythm that optimizes the use of gradient magnetic fields and minimizes total acquisition time.
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 improved spatial and time resolution in imaging tissues with short T2 or T2* relaxation times, while minimizing the influence of motion and flow, and allows for more flexible clinical applications with higher measurement accuracy and reduced acquisition time.
Implementation Method 1
magnetic resonance imaging (MRI) apparatuses
Implementation Method 2
a gradient magnetic field generation unit configured to generate gradient magnetic fields by applying current to gradient coils
Implementation Method 3
a radio frequency reception unit configured to detect echo signals generated by the subject
Data Source
AI summary
A magnetic resonance imaging apparatus according to an embodiment includes processing circuitry. The processing circuitry acquires an echo signal generated for each of intervals of repetition time by applying an excitation pulse to a subject at the intervals of repetition time, and acquires data of a plurality of trajectories set for a k-space using the echo signals. The processing circuitry acquires a plurality of echo signals by setting echo time to lengths different between a plurality of periods of repetition time and acquires data of the same trajectory using the echo signals, and the echo time serves as time from application of the excitation pulse to generation of the echo signal.