Flexible MRI Slice Ordering for Scan Time Reduction
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Solution Overview
Problem
In magnetic resonance imaging (MRI), the number of slices that can be interleaved within a desired repetition time (TR) is often limited, leading to suboptimal contrast or increased scan time, especially in T1-weighted imaging, due to constraints on TR and the number of excitations required for each slice.
Innovation Solution
A method for ordering slices in MRI that allows for varying numbers of excitations across different slices, with a flexible selection of repetition time (TR) and excitation duration, enabling efficient interleaving by filling a matrix with excitations and arranging them to minimize total scan time, accommodating fractional acquisitions and arbitrary ordering schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of slices is increased to improve coverage, then the scan time increases due to TR constraints
Solution Approach 1:
The patent applies dynamics by allowing the number of excitations per slice to vary dynamically rather than being fixed. Different slices can have different numbers of excitations (NE,S) based on their specific requirements, enabling flexible adaptation to minimize total scan time while maintaining optimal TR for contrast.
Solution Approach 2:
The patent changes the parameter of excitations per slice from a uniform fixed value to variable values. By allowing NE,S to differ for different slice numbers and enabling arbitrary ordering schemes, the system optimizes the balance between TR constraints and scan time efficiency.
2Quantity of substance
If TR is increased to accommodate all slices, then image contrast deteriorates
Solution Approach 1:
The patent segments the excitation process into multiple phases with different numbers of excitations for different slices. By dividing the acquisition into segments where each slice can have a customized number of excitations, the system maintains optimal TR for contrast while still acquiring all necessary slice data.
Solution Approach 2:
The patent applies local quality by assigning different numbers of excitations to different slices based on their specific requirements. Each slice can have tailored excitation parameters (NE,S) optimized for its position and imaging needs, rather than applying a uniform approach to all slices.
3Manufacturing precision
If multiple acquisitions are performed to improve contrast, then scan time increases
Solution Approach 1:
The patent merges multiple acquisition concepts into a single unified approach. By combining different excitation patterns and ordering schemes into one integrated acquisition protocol, the system achieves improved contrast without requiring separate acquisition passes, thus reducing total scan time.
Data Source
AI summary
A method of ordering slices for interleaved MRI is provided that includes selecting a number of interleaved slice locations (NS) each having a plurality of excitations (NE,S), where S is the slice number between 1 and NS and NE,S may differ for different slice numbers, selecting an excitation duration (TS) of each the excitation in each the slice, selecting a repetition time (TR) between successive excitations of the same slice, TR has a duration of Ni×TS, Ni is the number of interleaved slices per TR period, and arranging the order for the slices such that the total scan time (T) is minimized such that TR is the product of Ni and Ts, where Ni can be arbitrarily chosen between 1 and NT/NE,max where NT is the total number of excitations for all the slices and where NE,max is the maximum number of the excitations for one slice.