Simultaneous Multi-Slice MRI Phase Modulation Scan Time Reduction
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Solution Overview
Problem
Conventional simultaneous multi-slice (SMS) MRI methods require an additional reference scan, which increases scan time and impairs imaging efficiency by necessitating the acquisition of reference data for each slice location.
Innovation Solution
A system and method for SMS MRI that applies phase-encoding steps with phase modulation magnetic field gradients to acquire echo signals, reconstructs aliasing images, and generates reference slice images without an additional reference scan, allowing for the reconstruction of slice images based on these images using a parallel imaging reconstruction algorithm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an additional reference scan is performed to acquire reference data for slice separation, then slice image quality is improved, but scan time increases and imaging efficiency deteriorates
Solution Approach 1:
The patent combines the reference scan and the actual imaging scan into a single simultaneous acquisition process. By using multi-slice excitation with phase modulation, the system acquires both reference data and imaging data from multiple slices at the same time, eliminating the need for separate reference scans and thereby reducing total scan time while maintaining image quality
Solution Approach 2:
The system performs preliminary phase modulation on the excitation signals before acquisition, encoding slice-specific phase information that enables subsequent separation of slices without requiring additional reference scans. This preliminary encoding allows the reconstruction algorithm to separate slices directly from the simultaneously acquired data
2Measurement precision
If an additional reference scan is performed to determine coil sensitivity profiles, then slice separation accuracy is improved, but imaging efficiency deteriorates
Solution Approach 1:
The patent merges the acquisition of coil sensitivity profiles with the simultaneous multi-slice imaging acquisition. By incorporating phase modulation into the excitation signals during the main scan, the system extracts both imaging data and reference data for coil sensitivity estimation from the same simultaneous acquisition, maintaining slice separation accuracy while improving imaging efficiency
Solution Approach 2:
The system uses the simultaneously acquired multi-slice data to self-determine the coil sensitivity profiles needed for slice separation. The phase-modulated signals from multiple slices provide sufficient information for the reconstruction algorithm to automatically extract both the sensitivity profiles and separate the slices without external reference scans
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 eliminates the need for an additional reference scan, thereby reducing scan time and improving imaging efficiency by directly reconstructing slice images from acquired echo signals.
Implementation Method 1
A phase modulation magnetic field gradient may be applied during each of at least some of the plurality of PE steps in the frame
Implementation Method 2
apply a plurality of phase-encoding (PE) steps to each of a plurality of slice locations of a subject to acquire a set of echo signals
Implementation Method 3
reconstruct at least one slice image based on the plurality of aliasing images and the plurality of reference slice images
Implementation Method 4
A slice image of each individual slice location may be separated from an aliasing image acquired in SMS based on the coil sensitivity profiles
Data Source
AI summary
The present disclosure provides a system for SMS MRI. During each of a plurality of frames, the system may cause an MRI scanner to apply a plurality of PE steps to each of a plurality of slice locations of a subject to acquire echo signals. A phase modulation magnetic field gradient may be applied during each of at least some of the PE steps in the frame. For each frame, the system may reconstruct an aliasing image representative of the slice locations in the frame based on the corresponding echo signals. The system may also generate a plurality of reference slice images based on the aliasing images. The system may further reconstruct at least one slice image based on the aliasing images and the reference slice images. Each of the slice image may be representative of one of the slice locations in one of the frames.