Magnetic Resonance Slice Excitation Timing to Reduce Crosstalk
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Solution Overview
Problem
Magnetic resonance (MR) imaging faces challenges with slice crosstalk, where excitation of one slice inadvertently magnetizes adjacent slices, leading to signal losses and contrast changes, particularly in quantitative imaging, due to the finite bandwidth of RF excitation pulses, which users cannot effectively manage without specialized knowledge.
Innovation Solution
A method to determine and adapt time intervals between neighboring slice excitations based on pulse sequence, tissue, and quality parameters to ensure minimum intervals that prevent crosstalk, using a magnetic resonance apparatus with a control device to automatically adjust these intervals, thereby avoiding artifacts while minimizing measurement time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the distance between slices is reduced to increase the number of slices measured, then productivity is improved, but slice crosstalk increases leading to signal losses and contrast changes
Solution Approach 1:
The system performs preliminary calculation of slice excitation profiles and predicts crosstalk effects before the actual measurement. Based on these predictions, it proactively adjusts the time intervals between slice excitations to prevent crosstalk artifacts, rather than reacting to them after they occur. This allows tight slice spacing while maintaining image quality.
Solution Approach 2:
The system calculates slice excitation profiles and uses this information as feedback to automatically adjust measurement parameters (time intervals between slice excitations). This closed-loop approach ensures that even when slices are placed close together, the timing is optimized to minimize crosstalk, thereby maintaining both high productivity and image quality.
2Object-affected harmful factors
If the time interval between slice excitations is increased to reduce crosstalk, then slice crosstalk is reduced, but measurement time increases
Solution Approach 1:
The system calculates slice excitation profiles and determines optimal time intervals before the measurement begins. This preliminary optimization allows the use of minimal necessary time intervals that still prevent crosstalk, rather than using conservative fixed intervals, thereby minimizing measurement time while maintaining image quality.
Solution Approach 2:
Instead of using fixed time intervals for all slice combinations, the system dynamically adjusts the time intervals between slice excitations based on the specific geometry and spacing of the slices being measured. This adaptive approach allows shorter intervals where crosstalk is minimal and longer intervals only where necessary, optimizing overall measurement time.
3Object-affected harmful factors
If users manually adjust measurement parameters to avoid crosstalk, then slice crosstalk is reduced, but ease of operation deteriorates due to required specialized knowledge
Solution Approach 1:
The system performs self-optimization by automatically calculating slice excitation profiles, predicting crosstalk effects, and adjusting measurement parameters without user intervention. This eliminates the need for users to have specialized knowledge about RF pulse bandwidths and slice spacing relationships, making the system easy to operate while maintaining image quality.
Solution Approach 2:
The system automatically changes measurement parameters (time intervals between slice excitations) based on calculated slice excitation profiles. This automated parameter optimization removes the burden from users to manually adjust these complex parameters, improving ease of operation while effectively preventing crosstalk artifacts.
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 solution effectively reduces slice crosstalk artifacts without unnecessarily extending measurement time, ensuring high-quality MR imaging by maintaining desired contrast and accuracy, particularly in quantitative MR measurements.
Implementation Method 1
To trigger nuclear spin resonances radio-frequency excitation pulses (RF pulses) are radiated into the examination object
Implementation Method 2
By means of a slice selective excitation by RF excitation pulses with a corresponding bandwidth and simultaneous switching of gradient fields in the slice selection direction
Implementation Method 3
For spatial encoding of the measurement data, rapidly switched magnetic gradient fields are superimposed on the basic magnetic field
Implementation Method 4
Determination of a minimum time interval between excitations of neighboring slices carried out within the framework of the pulse sequence on the basis of parameters from the group of pulse sequence parameters, tissue parameters of the examination region
Data Source
AI summary
Techniques are disclosed for acquiring data of an examination object in at least two slices by means of a pulse sequence. Time intervals between excitations of neighboring slices and associated minimum intervals are determined. From these, time intervals to be adapted between excitations of neighboring slices are determined and adapted before a measurement protocol is executed, with the adapted time intervals. Through the determination of a minimum time interval between excitations of neighboring slices and the adaptation of the time intervals between excitations of neighboring slices, a falsification of measurement results can be avoided, measurement time of the chosen measurement protocol is not increased, and the user is not restricted in their choice of the slices to be excited.