MICA Multislice MRI Using Pseudo-Random Phase Encoding
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Solution Overview
Problem
Current magnetic resonance imaging (MRI) techniques face challenges in efficiently reconstructing images from simultaneous multislice acquisitions due to coherent aliasing, which leads to reduced signal-to-noise ratio (SNR) and limitations in acceleration factors.
Innovation Solution
The Multislice Acquisition with InCoherent Aliasing (MICA) technique introduces pseudo-random encoding of slices, resulting in incoherent aliasing across the field-of-view, allowing for improved SNR retention and flexible encoding schemes that can vary with time, enabling better reconstruction performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If parallel imaging techniques are used to speed up MRI acquisitions by acquiring aliased signal from multiple spatial locations, then productivity is improved, but measurement precision deteriorates due to reduced signal-to-noise ratio
Solution Approach 1:
The patent changes the encoding parameters by introducing time-varying pseudo-random phase encoding schemes that modulate the aliasing pattern across different time points. This transforms the coherent aliasing problem into an incoherent one, allowing for better SNR retention during parallel imaging reconstruction while maintaining high acceleration factors
Solution Approach 2:
The patent employs periodic modulation of the phase encoding gradients with pseudo-random sequences across multiple excitations. This periodic variation in encoding patterns enables the separation of aliased signals through reconstruction algorithms while preserving signal-to-noise ratio by distributing the aliasing incoherently over time
2Productivity
If higher acceleration factors are used in parallel imaging, then productivity is improved, but measurement precision worsens due to further reduction in signal-to-noise ratio
Solution Approach 1:
The patent introduces time-varying pseudo-random phase encoding parameters that change across multiple excitations. This dynamic parameter modulation allows the system to achieve higher acceleration factors while maintaining acceptable SNR levels by creating incoherent aliasing patterns that are more amenable to reconstruction
3Device complexity
If conventional parallel imaging with coherent aliasing is used, then device complexity is reduced, but measurement precision deteriorates due to limitations in reconstruction performance
Solution Approach 1:
The patent implements periodic pseudo-random phase encoding schemes that modulate the aliasing pattern across time. While this increases encoding complexity compared to conventional methods, it significantly improves reconstruction performance by transforming coherent aliasing into incoherent aliasing that can be more effectively separated during image reconstruction
Solution Approach 2:
The patent employs dynamic phase encoding patterns that vary over time rather than static encoding schemes. This temporal dynamics in the encoding process enables better separation of aliased signals during reconstruction, improving measurement precision despite the increased complexity of the time-varying encoding scheme
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
MICA achieves higher SNR in reconstructed images compared to conventional methods, particularly at higher acceleration factors, and allows for improved compressed sensing reconstructions and more accurate diffusion tensor analysis.
Implementation Method 1
Magnetic resonance imaging (MRI) is a widely used imaging modality
Implementation Method 2
The RF field or magnetic field gradient is manipulated along a slice-select direction in order to impart a sequence of phase shifts to the formed echo signals such that image data corresponding to the at least one adjacent slice location is incoherently aliased across a field-of-view (FOV) of the current slice location
Data Source
AI summary
A method for producing images of a subject with a MRI system is provided. A radio frequency (RF) excitation field in combination with a slice-select magnetic gradient field along a slice-select direction is provided. At least one readout magnetic field gradient is established along a frequency-encoding direction and at least one phase encoding magnetic field gradient along a phase-encoding direction. The RF field or magnetic field gradient is manipulated along a slice-select direction in order to impart a sequence of phase shifts to the formed echo signals such that image data corresponding to an at least one adjacent slice location is incoherently aliased across a field-of-view (FOV) of a current slice location. Image data is acquired indicative of the formed echo signals. A plurality of images of the subject is reconstructed.