MRI Gradient Switching for Short Echo Time Acquisition
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Solution Overview
Problem
Current magnetic resonance imaging (MRI) techniques face challenges in acquiring scan data with short echo times, particularly for substances with transverse relaxation times (T2) of 30-80 μs, such as bones, due to high noise levels and prolonged scan times, which limit the representation of these tissues in MR images.
Innovation Solution
A method involving a magnetic resonance system that switches constant gradients and additional gradients with modulating amplitudes to increase k-space coverage, allowing for efficient acquisition of scan data with reduced noise and shorter scan times, enabling the representation of substances with short T2 times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional gradient echo sequences are used for MRI, then scan data can be acquired, but the noise level becomes excessively high and scan time becomes unacceptably long for substances with short T2 times
Solution Approach 1:
The patent divides k-space into multiple segments and acquires data from different segments using different gradient constellations and echo times. This segmentation allows optimization for short T2 substances by acquiring early echo data for high signal-to-noise ratio while using later echoes for other regions, thereby reducing overall scan time without sacrificing measurement precision for critical short T2 tissues
Solution Approach 2:
The patent dynamically adjusts gradient constellations and echo times based on the specific k-space region being acquired. By varying the gradient switching patterns and echo times adaptively across different k-space segments, the system optimizes signal acquisition for short T2 substances while maintaining acceptable scan times through intelligent parameter modulation
2Speed
If gradient switching is increased to enable short echo times, then echo time can be reduced, but noise level increases and patient discomfort increases
Solution Approach 1:
The patent applies different gradient switching strategies and echo times to different regions of k-space rather than using a uniform approach. By tailoring the acquisition parameters locally to each k-space segment, the system achieves short echo times where critical for short T2 substance visualization while reducing noise in regions where rapid gradient switching is less critical, thereby minimizing overall noise levels while maintaining short echo times for essential data
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 accelerated acquisition of scan data with short echo times, reducing the number of repetitions needed and minimizing noise, thereby allowing for clinically acceptable scan times and improved representation of tissues like bones in MRI images.
Implementation Method 1
For position encoding of the scan data, rapidly switched magnetic gradient fields, abbreviated to gradients, are overlaid on the main magnetic field
Implementation Method 2
Radiofrequency excitation pulses (RF pulses) are radiated into the examination object in order to induce nuclear spin resonances which can be measured as signals
Implementation Method 3
placing the examination object in a magnetic resonance apparatus in a comparatively strong static, homogeneous main magnetic field, also called the B0 field, at field strengths of 0.2 Tesla to 7 Tesla and higher, with the result that the nuclear spins of the examination object are oriented along the main magnetic field
Data Source
AI summary
Accelerated acquisition of scan data by means of magnetic resonance to enable short echo times so that scan data of substances can also be acquired with a transversal relaxation time.