MRI Echo Time Minimization for Short T2 Imaging
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Solution Overview
Problem
Conventional magnetic resonance imaging (MRI) systems face limitations in capturing substances or tissues with very short T2 times, as their signal decays before conventional echo times can be achieved, preventing the depiction of materials like bones or ice.
Innovation Solution
The method involves activating two or three phase coding gradients to minimize echo time, allowing for individual determination of each raw data point's acquisition time based on gradient strength and resolution, enabling the acquisition of MR images with significantly reduced echo times and the ability to depict previously invisible substances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional echo times are used in MRI, then the imaging system can capture standard tissues, but substances with very short T2 times (like bones or ice) cannot be depicted because their signal decays before the echo time is achieved
Solution Approach 1:
The patent applies dynamics by making the echo time variable rather than fixed. The system dynamically adjusts the echo time for each individual raw data point based on its specific requirements, allowing optimization for substances with very short T2 times while maintaining adequate sampling according to the Nyquist theorem.
Solution Approach 2:
The patent changes the parameter of echo time from a constant value to a variable value that is individually determined for each raw data point. This parameter change enables the system to adapt to different tissue characteristics and capture signals from substances with varying T2 relaxation times.
2Measurement precision
If the echo time is reduced to capture substances with short T2 times, then these substances can be depicted, but the acquisition time for the entire MR image increases
Solution Approach 1:
The system dynamically determines the minimum necessary echo time for each raw data point individually, rather than using a uniform echo time for all data points. This dynamic approach allows the acquisition to be optimized for each point's specific requirements, balancing the need to capture short T2 signals with overall acquisition efficiency.
Solution Approach 2:
By changing the echo time parameter from a fixed system-wide value to variable point-specific values, the patent enables precise timing optimization for each raw data point while maintaining compliance with the Nyquist theorem, thus resolving the contradiction between detecting short T2 substances and maintaining reasonable acquisition time.
3Measurement precision
If a constant echo time is used for all raw data points, then the acquisition process is simplified, but substances with very short T2 times cannot be captured because their signal decays before the echo is achieved
Solution Approach 1:
The patent introduces dynamics into the echo time determination process by calculating individual minimum echo times for each raw data point based on the gradient strengths and resolutions required for that specific point, rather than applying a constant echo time universally.
Solution Approach 2:
The echo time parameter is transformed from a constant system parameter to a variable parameter that is individually optimized for each raw data point, enabling detection of short T2 substances while managing complexity through systematic calculation based on gradient parameters.
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 allows for the depiction of substances with very short T2 times by minimizing echo times, reducing image acquisition time, and enabling the visualization of previously undetectable tissues, while adhering to the Nyquist theorem to ensure accurate data acquisition.
Implementation Method 1
Schalten Sie zwei oder drei Phase-Coding-Gradienten schaltbar an, um die Phase in einer jeweiligen räumlichen Richtung zu kodieren
Implementation Method 2
Strahlen Sie einen RF-Anregungsimpuls aus
Data Source
AI summary
In a method to create an image data set by operating a magnetic resonance system, at least two phase coding gradients are switched in respective spatial directions, an RF excitation pulse is radiated and a raw data point in a k-space data set belonging to the image data set is read out a predetermined time period after the radiation of the RF excitation pulse. The predetermined time period thereby corresponds to the maximum of a set of a respective minimum time period for each of the at least two phase coding gradients. The minimum time period of the respective at least one of the at least two phase coding gradients is determined depending on the strength of the respective phase coding gradient such that the Nyquist theorem is complied with.