MRSI Multiplexing Slabs for SNR and Chemical Shift Artifacts
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Solution Overview
Problem
Magnetic resonance spectroscopic imaging (MRSI) faces challenges in achieving high signal-to-noise ratio (SNR) per unit time and optimizing duty cycle, especially at high magnetic fields, due to low concentrations of brain metabolites and chemical shift artifacts.
Innovation Solution
The method involves multiplexing several slabs of slices in space and time to optimize SNR and duty cycle, and reducing chemical shift artifacts by segmenting the volume-of-interest into thinner slabs and using sequentially cascaded Hadamard selective pulses, which allows for a stronger slice-select gradient and reduced RF power requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If MRS voxels are made larger to improve SNR, then signal-to-noise ratio improves, but spatial resolution deteriorates
Solution Approach 1:
The patent divides the volume of interest into multiple thin slabs along the frequency-encode direction, with each slab containing multiple slices. This segmentation allows independent Hadamard encoding of slices within each slab, enabling improved spatial resolution while maintaining adequate SNR through optimized multiplexing of the segmented structures.
Solution Approach 2:
The patent introduces a new dimension for multiplexing by encoding slices within each slab using Hadamard encoding along the frequency-encode direction, in addition to the conventional phase-encode direction. This dimensional approach allows simultaneous acquisition of multiple slices while maintaining spatial resolution and improving SNR through efficient k-space sampling.
2Productivity
If acquisition time is reduced to improve productivity, then scanning speed improves, but signal-to-noise ratio deteriorates
Solution Approach 1:
The patent implements continuous data acquisition by multiplexing multiple slabs within a single repetition time TR, eliminating idle time between acquisitions. By acquiring data from multiple slabs sequentially within each TR period, the system maintains continuous useful action, improving productivity without sacrificing SNR through optimized duty cycle.
Solution Approach 2:
The patent uses periodic Hadamard encoding patterns to cycle through different slice combinations within each slab during successive TR periods. This periodic action allows efficient sampling of k-space from multiple slabs, accelerating acquisition while maintaining SNR through coherent signal accumulation across periodic cycles.
3Object-affected harmful factors
If slice-select gradient is increased to reduce chemical shift artifacts, then artifact reduction improves, but RF power requirements worsen
Solution Approach 1:
The patent segments the volume into multiple thin slabs, allowing the use of lower amplitude slice-select gradients within each slab while maintaining adequate spatial resolution. This segmentation reduces the gradient strength needed, thereby reducing RF power requirements while still minimizing chemical shift artifacts through the combined effect of multiple slabs.
Solution Approach 2:
The patent changes the parameter of slab thickness by dividing the volume into multiple thinner slabs, which allows optimization of the gradient amplitude and duration parameters. This parameter change enables reduced RF power consumption while maintaining artifact reduction through adjusted gradient timing and strength profiles for each thinner slab.
4Productivity
If duty cycle is increased to improve productivity, then acquisition efficiency improves, but signal-to-noise ratio deteriorates
Solution Approach 1:
The patent segments the acquisition into multiple slabs with multiple slices each, allowing optimized multiplexing where the number of slices per slab and slabs per TR can be independently adjusted. This segmentation enables duty cycle optimization to maximize productivity while maintaining SNR through balanced distribution of acquisitions across segmented structures.
Solution Approach 2:
The patent implements dynamic adjustment of the encoding scheme by allowing variable numbers of slices per slab and variable slabs per TR based on specific imaging requirements. This dynamic approach enables optimization of duty cycle for productivity while preserving SNR through adaptive multiplexing factors that can be tuned for different clinical scenarios.
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 results in improved SNR and acquisition efficiency, with twice as many voxels at 3 T having the same SNR and size as conventional techniques, and significantly reduces chemical shift artifacts, making MRSI more feasible for clinical use at higher magnetic fields.
Implementation Method 1
Magnetic resonance spectroscopy ('MRS') provides in vivo information regarding the concentration of specific metabolites
Implementation Method 2
at least one excitation pulse is forwarded to a target
Data Source
AI summary
An exemplary embodiment of system, method, and computer accessible medium for magnetic resonance spectroscopic imaging for improving signal-to-noise ratio per unit time and optimizing duty cycle in MRSI and/or for reducing chemical-shift artifacts can be provided. In one exemplary embodiment, an excitation pulse can be forwarded to the target and acquiring a signal from the target by multiplexing in time and space. The multiplexing procedure in time can involve (i) a segmentation of a field of view of the at least one portion of the target into a predetermined number of slabs that are acquired sequentially during each repetition time, and/or (ii) an acquisition of multiple voxels. Data can be generated based on the acquired signal. According to another exemplary embodiment, an excitation pulse can be provided to the target, and a signal can be acquired from the target. The excitation pulse can be a series of cascaded Hadamard pulse components. Data can be generated based on the acquired signal.