MRI Multi-Slice Reconstruction for Single-Breath-Hold Heart Scans
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Solution Overview
Problem
Conventional MRI scans require multiple breath-holds for whole heart imaging, leading to prolonged scan times and discomfort for patients, especially those with breathing difficulties, and existing SMS and CS techniques have limitations in efficiency and applicability.
Innovation Solution
A system and method combining SMS imaging and CS techniques, utilizing phase modulation magnetic field gradients and RF excitation pulses to reconstruct slice images without additional reference scans, enabling simultaneous multi-slice imaging and reducing scan time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional cine MR scan scans one or two slices per breath-hold, then the scan coverage is limited, but the scan time is prolonged and patient comfort deteriorates
Solution Approach 1:
The patent divides the imaging task into multiple simultaneously acquired slice groups. Instead of scanning slices sequentially in one breath-hold, the system segments the field of view into multiple slice locations and acquires them simultaneously using multi-band excitation, thereby expanding scan coverage without extending scan time.
Solution Approach 2:
The patent introduces slice encoding dimension to differentiate between simultaneously acquired slices. By applying phase modulation magnetic field gradients along the slice encoding direction, the system encodes spatial information from multiple slice locations into the signal, enabling reconstruction of individual slices from simultaneously acquired data.
2Area of stationary object
If multiple breath-holds are used for whole heart cine scan, then complete coverage is achieved, but patient comfort and reliability deteriorate
Solution Approach 1:
The patent segments the whole heart imaging task into multiple slice groups that can be simultaneously acquired within a single breath-hold. This segmentation allows complete heart coverage to be achieved without requiring multiple breath-holds, thereby improving patient comfort and reducing motion artifacts from repeated breathing cycles.
Solution Approach 2:
The patent enables continuous imaging action within a single breath-hold by simultaneously acquiring multiple slice groups. This eliminates the interruption and repositioning required by multiple breath-holds, maintaining continuous data acquisition and improving image quality through reduced motion variability.
3Productivity
If SMS imaging technique excites multiple slice locations simultaneously, then scan efficiency is improved, but image reconstruction complexity increases
Solution Approach 1:
The patent adds slice encoding dimension to the acquisition process, creating a four-dimensional data structure (x, y, slice group, slice position within group). This dimensional expansion enables systematic organization of simultaneously acquired data and facilitates efficient reconstruction algorithms that can separate overlapping slice signals through Fourier transformation along the slice encoding direction.
Solution Approach 2:
The patent employs iterative reconstruction algorithms that use feedback from preliminary reconstructions to refine the final images. The system initially reconstructs images from the multi-dimensional k-space data, identifies residual aliasing artifacts, and applies corrective processing to improve image quality, creating a feedback loop that enhances reconstruction accuracy.
4Measurement precision
If phase modulation magnetic field gradient is applied during PE steps, then slice separation is improved, but gradient system complexity increases
Solution Approach 1:
The patent utilizes the slice encoding gradient dimension to achieve slice separation. By applying phase modulation gradients along this additional dimension, the system encodes unique spatial frequency information for each slice location, enabling precise slice separation through Fourier transformation without requiring complex modifications to the existing gradient system architecture.
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
Accelerates MRI scans by allowing simultaneous multi-slice imaging, reducing the need for breath-holds and improving scanning efficiency, enabling whole heart cine scans in under 12 seconds with 16-fold acceleration.
Implementation Method 1
magnetic resonance imaging (MRI)
Implementation Method 2
apply a plurality of phase-encoding (PE) steps to each of a plurality of slice locations
Implementation Method 3
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 4
phase modulation magnetic field gradient
Implementation Method 5
reconstruct an aliasing image representative of the plurality of slice locations in the frame based on the corresponding set of echo signals
Implementation Method 6
RF excitation pulses
Data Source
AI summary
A system for MRI is provided. The system may obtain a plurality of sets of under-sampled k-space data corresponding to a plurality of frames. Each set of under-sampled k-space data may be acquired simultaneously from a plurality of slice locations of a subject in one of the frames using an MRI scanner. The system may reconstruct a plurality of reference slice images based on the sets of under-sampled k-space data of the plurality of frames. Each of the reference slice images may be representative of one of the slice locations in more than one frame of the frames. The system may further reconstruct a plurality of image series based on the sets of under-sampled k-space data and the reference slice images. Each image series may correspond to one of the slice locations and include a plurality of slice images of the corresponding slice location in the plurality of frames.