Simultaneous Multi-Slice MRI Using Phase Cycling and Spiral Trajectories
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Solution Overview
Problem
Current 3D myocardial perfusion techniques using cardiac magnetic resonance imaging (CMR) face limitations in spatial and temporal resolution, especially when aiming for whole-heart coverage, with existing methods struggling to achieve high-quality images across multiple slices simultaneously.
Innovation Solution
The implementation of simultaneous multi-slice (SMS) imaging using a spiral k-space trajectory and phase cycling schemes to modulate the excitation phase, allowing for the simultaneous acquisition and reconstruction of multiple slices with reduced aliasing artifacts, enabling whole-heart coverage while maintaining spatial-temporal resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If 3D imaging techniques are used to achieve whole-heart coverage, then spatial coverage is improved, but temporal and spatial resolution deteriorate
Solution Approach 1:
The patent divides the 3D imaging problem into multiple 2D slices that are acquired simultaneously. By segmenting the volume into discrete slices and using parallel excitation, the system achieves whole-heart coverage while maintaining the high temporal and spatial resolution of 2D imaging, thus resolving the contradiction between coverage and resolution
Solution Approach 2:
The patent combines multiple slice acquisitions into a single simultaneous multi-slice experiment. By merging the acquisition of multiple slices into one scan, the system achieves both comprehensive heart coverage and high temporal resolution, as all slices are captured at the same time point rather than sequentially
2Productivity
If multiple slices are acquired simultaneously, then productivity is improved, but image quality deteriorates due to aliasing artifacts
Solution Approach 1:
The patent introduces an intermediary reconstruction process that separates the aliased signals from simultaneously acquired slices. Using parallel imaging techniques and coil sensitivity information as intermediaries, the system mathematically decomposes the mixed signals to recover individual slice images with high quality, thus resolving the aliasing problem while maintaining productivity
Solution Approach 2:
The patent changes the excitation parameters by applying different phase cycles to different slices in the simultaneous multi-slice acquisition. This parameter modulation allows the reconstruction algorithm to distinguish between slices and eliminate aliasing artifacts, thereby maintaining image quality while achieving high productivity through simultaneous acquisition
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 achieves high-quality, unaliased images across multiple slices, improving spatial-temporal resolution and efficiency in perfusion imaging, with minimal residual aliasing even at higher multi-band factors, comparable to single-slice image quality.
Implementation Method 1
simultaneously exciting multiple, different slice locations corresponding to a region of interest of a subject using a radio-frequency (rf) pulse
Implementation Method 2
The excitation phase is modulated between acquisitions using a phase cycling scheme configured to create signal cancellation of all but one slice
Implementation Method 3
applying an imaging pulse sequence using a spiral k-space trajectory to acquire image data from the multiple slices
Implementation Method 4
rotating the phase of the excitation between heartbeats of the subject to create temporal incoherence of a residual aliasing pattern of aliasing
Data Source
AI summary
Systems and methods for simultaneous multi-slice imaging. In one embodiment, a method for magnetic resonance imaging of a region of interest of a subject includes simultaneously exciting multiple, different slice locations corresponding to a region of interest of a subject using a radio-frequency (rf) pulse, for obtaining multiple slices. The excitation phase is modulated between acquisitions using a phase cycling scheme configured to create signal cancellation of all but one slice of the multiple excited slices from the different slice locations. The method also includes applying an imaging pulse sequence using a spiral k-space trajectory to acquire image data from the multiple slices, for an image or series of images of the region of interest; and reconstructing, from the multiple slices, images of the region of interest, wherein the reconstructing recovers unaliased images from the different slice locations.