Simultaneous Multi-Slice MRI Interleaving to Reduce Slice Crosstalk
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Solution Overview
Problem
Existing simultaneous multi-slice (SMS) magnetic resonance imaging techniques suffer from slice crosstalk artifacts and suboptimal signal-to-noise ratio (SNR) due to non-optimal slice excitation profiles and acquisition orders, particularly when the total number of slices divided by the acceleration factor results in an even number.
Innovation Solution
A method to determine an improved acquisition order by calculating multiple reordering schemes and applying decision criteria to select an interleaving scheme that minimizes slice crosstalk and enhances SNR, using a computer-implemented approach to analyze spatial distances and SNR variations among slice groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If slices are acquired in temporal and spatial vicinity using conventional interleaving schemes, then acquisition efficiency is improved, but slice crosstalk artifacts increase due to non-optimal slice excitation profiles
Solution Approach 1:
The patent applies dynamics by making the slice acquisition order adaptive rather than fixed. The system dynamically adjusts the temporal spacing between acquisitions of spatially adjacent slices based on their relaxation times, allowing optimal spacing that prevents crosstalk while maintaining high acquisition efficiency. This is achieved through calculating and applying variable inter-acquisition delays tailored to specific slice characteristics.
Solution Approach 2:
The patent changes the temporal parameter (acquisition timing) of slice groups to resolve the contradiction. By modifying the time spacing between acquisitions of slices that are spatially adjacent, the system prevents saturation from previous excitations while maintaining efficient overall acquisition. This parameter adjustment directly addresses the crosstalk issue without sacrificing productivity.
2Object-generated harmful factors
If slices are spaced further apart in time to reduce crosstalk, then slice crosstalk artifacts are reduced, but acquisition time increases
Solution Approach 1:
The patent applies local quality by treating different slice groups differently based on their specific characteristics. Rather than uniformly spacing all slices, the system calculates and applies customized temporal spacing for each pair of spatially adjacent slices based on their relaxation times and signal characteristics. This localized optimization reduces crosstalk for each specific slice pair while minimizing overall acquisition time extension.
Solution Approach 2:
The patent performs preliminary calculation of optimal acquisition spacing before the actual imaging sequence. By pre-calculating the required temporal spacing between slice acquisitions based on relaxation times and crosstalk considerations, the system prepares an optimized schedule that prevents crosstalk artifacts while maintaining efficient timing. This preliminary planning avoids unnecessary delays during actual acquisition.
3Ease of operation
If conventional interleaving schemes are used for even collapsed slice numbers, then implementation simplicity is maintained, but slice crosstalk artifacts increase due to adjacent slices being acquired in consecutive sequence sections
Solution Approach 1:
The patent makes the interleaving scheme dynamic and adaptive rather than using fixed conventional patterns. The system automatically calculates optimal acquisition ordering based on slice characteristics and crosstalk considerations, adapting the temporal spacing for each slice group. This dynamic approach handles both even and odd collapsed slice numbers optimally without requiring different fixed schemes, maintaining ease of operation while eliminating crosstalk.
Solution Approach 2:
The patent incorporates feedback mechanisms by using measured or estimated relaxation times and signal characteristics to determine optimal acquisition spacing. The system uses this feedback information to adjust the temporal ordering and spacing of slice acquisitions, ensuring that slices prone to crosstalk are adequately spaced while maintaining overall efficiency. This feedback-driven approach automatically adapts to different slice configurations.
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
Reduces slice crosstalk artifacts and improves image quality and SNR in SMS imaging, offering flexibility in choosing the number of slices and providing optimized interleaving schemes for both even and odd collapsed slice numbers.
Implementation Method 1
magnetic resonance device to acquire a magnetic resonance data set
Implementation Method 2
simultaneously excited, for example using a multi-band pulse
Data Source
Figure 1
Figure 2~3
AI summary
Computer-implemented method for operating a magnetic resonance device (14) to acquire a magnetic resonance data set, which comprises a total number of slices, using a simultaneous multislice technique, wherein in each sequence section of a repetition sequence, which is repeated multiple times, magnetic resonance signals from a simultaneity number, which is equal to an acceleration factor, of at least two slices, which have been excited in this sequence section, are measured simultaneously, wherein, to determine an acquisition order, - a collapsed slice number, determined as the total number of slices divided by the acceleration factor, of slice groups is determined, wherein the slices are numbered according to their spatial arrangement in at least one stacking direction and the slice groups are defined such that the slice numbers in each group differ by the collapsed slice number, wherein the slice groups are numbered according to the lowest slice number among their slices, and - slice groups are assigned to the sequence sections according to an interleaving scheme applied to the slice groups sorted by their slice numbers, wherein the interleaving scheme is determined by - determining multiple different reordering schemes for the slice groups, and - using at least one decision criterion, which describes at least an estimated slice crosstalk strength for the reordering schemes, to choose one of the reordering schemes as the interleaving scheme.