MRI Spin Preparation Module for Steady State Signal Suppression
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Solution Overview
Problem
Current MRI techniques face challenges in suppressing signals from specific tissue types, such as fat tissue, which can lead to impaired image quality, especially in organs with quasi-periodical movement, requiring extended measurement times or incomplete suppression.
Innovation Solution
A magnetic resonance imaging sequence that includes a spin preparation module to shift the magnetization of nuclear spins into a steady state condition, allowing for rapid and effective suppression of signals from specific tissue types, thereby improving image quality and reducing acquisition time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If suppression modules are rapidly repeated to suppress fat tissue signals, then signal suppression effectiveness is improved, but measurement time is extended due to discarding initial modules
Solution Approach 1:
A spin preparation module is applied before the repeated suppression modules to pre-establish the steady state condition of nuclear spin magnetization. This preliminary action eliminates the need to discard initial suppression modules, allowing immediate effective suppression from the first measurement cycle while maintaining short repetition times.
2Productivity
If repetition time is reduced to enable rapid acquisition, then productivity is improved, but steady state condition is not achieved and suppression is incomplete
Solution Approach 1:
The spin preparation module performs preliminary magnetization manipulation to directly establish the steady state condition before the rapid repeated suppression-acquisition cycles begin. This allows the system to achieve both fast repetition times and complete suppression effectiveness simultaneously.
Solution Approach 2:
The invention changes the initial magnetization state parameters through the spin preparation module, transforming the nuclear spin system into a steady state condition with specific magnetization characteristics that enable effective suppression at short repetition times.
3Device complexity
If conventional suppression sequences are used without spin preparation, then device complexity is reduced, but image quality deteriorates due to inconsistent suppression
Solution Approach 1:
The spin preparation module serves as a preliminary step that establishes consistent steady state conditions before the main suppression-acquisition cycles. This simple additional module ensures uniform suppression effectiveness across all repeated cycles, improving image quality without significantly increasing sequence complexity.
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
The sequence achieves consistent and accelerated image data acquisition with improved suppression of specific tissue signals, enhancing image quality and allowing for efficient data acquisition even in organs with movement, by inducing a steady state condition in the magnetization of nuclear spins.
Implementation Method 1
Radio-frequency excitation pulses are radiated into the examination subject to trigger nuclear magnetic resonance signals
Implementation Method 2
The examination subject is positioned in a strong, static, homogeneous basic magnetic field (field strengths of 0.2 Tesla up to 7 Tesla and more) in an MR apparatus so that the subject's nuclear spins orient along the basic magnetic field
Implementation Method 3
The application of the IR pulse inverts the longitudinal magnetization of the nuclear spins that thereupon again approach their initial position (i.e. the alignment parallel to the B0 magnetic field) in an exponential curve with a time constant T1
Implementation Method 4
Since protons of fat tissue and of water have slightly different resonance frequencies, it is possible to excite predominantly fat tissue protons with a specific RF pulse and to thereupon destroy (dismantle) the generated signal with a gradient pulse (what is known as a spoiler gradient)
Data Source
AI summary
A method in the form of a sequence for magnetic resonance imaging with which image data of a subject to be examined are acquired and with which signals of nuclear spins of a specific type are suppressed, includes the steps of (a) application of a suppression module to suppress signals of the nuclear spins of the specific type, (b) application of an acquisition module after a wait time to acquire measurement data, (c) repetition of the steps (a) and (b) one or more times, respectively after a repetition time and, (d) before the steps (a), (b) and (c), application of a spin preparation module that shifts a magnetization of the nuclear spins of the specific type into a steady state condition that is maintained through the application of the subsequent steps (a), (b) and (c). Alternatively, instead of the spin preparation module the first suppression module can be fashioned such that it has an RF pulse with a flip angle selected such that the magnetization of the nuclear spins of the specific type is shifted into a steady state condition.