Simultaneous Multislice MRI Reconstruction via Phase Modulation
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Solution Overview
Problem
Magnetic Resonance Imaging (MRI) techniques face challenges with long scan times and low signal-to-noise ratios, especially in low-field systems, and are vulnerable to motion artifacts due to the need for repeated phase modulation schemes in simultaneous multislice imaging methods.
Innovation Solution
A method that uses multi-band radio-frequency excitation pulses to simultaneously excite multiple slices, with phase modulation and spatial registration to correct for translational and rotational motion, resulting in improved image quality by reconstructing corrected MR images from collapsed datasets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If simultaneous multislice excitation with phase modulation is used, then scan time is reduced, but motion artifacts increase
Solution Approach 1:
The patent applies preliminary action by performing spatial registration and motion correction on collapsed images before final slice reconstruction. Motion correction parameters are calculated from collapsed images that combine information from multiple slices, providing more robust motion estimation than traditional methods. This preliminary motion correction is then applied to individual slice data, preventing motion artifacts in the final images while maintaining the speed benefits of simultaneous multislice excitation.
Solution Approach 2:
The patent uses collapsed images as an intermediary structure in the imaging pipeline. These collapsed images serve as a mediator that combines signal information from multiple simultaneously excited slices, allowing motion correction to be performed on a composite dataset that is more robust to noise and provides better motion estimation. This intermediary step enables accurate motion correction without requiring sequential slice acquisition.
2Productivity
If multi-band RF excitation pulses are used to excite multiple slices simultaneously, then productivity increases, but device complexity increases
Solution Approach 1:
The patent segments the imaging process into distinct stages: simultaneous multislice excitation with phase modulation, collapsed image formation, spatial registration, motion correction, and final slice reconstruction. Each stage handles a specific aspect of the problem, allowing the complex task of simultaneous multislice imaging to be broken down into manageable steps. This segmentation enables the use of standard MRI hardware while achieving advanced imaging capabilities through systematic process division.
3Measurement precision
If spatial registration and motion correction are performed, then image quality improves, but processing time increases
Solution Approach 1:
The patent implements self-service by using the collapsed images themselves to provide motion correction information for the individual slices. The spatial registration and motion correction are performed using data that is already available from the simultaneous multislice excitation, without requiring additional reference scans or external correction data. The collapsed images serve their dual purpose of both being intermediates for motion estimation and providing the correction parameters needed for slice reconstruction, making the system self-sufficient.
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 enhances image quality and robustness in low-field MRI systems by reducing scan time and motion artifacts, providing accurate reconstruction of MR images even under difficult imaging conditions.
Implementation Method 1
executing an MR imaging sequence using multi-band radio-frequency (RF) excitation pulses to excite the at least two slices simultaneously
Implementation Method 2
the repetitions are executed according to a phase modulation scheme, in which each of the simultaneously excited slices is assigned a phase in each repetition
Implementation Method 3
Magnetic resonance imaging (MRI) is an important imaging modality in modern medicine and biology
Data Source
AI summary
A method is for acquiring a magnetic resonance (MR) image dataset of at least two slices via simultaneous multi-slice excitation. An embodiment of the method includes executing an MR imaging sequence using multi-band radio-frequency excitation pulses to excite the at least two slices simultaneously in at least two repetitions, the repetitions each being executed according to a phase modulation scheme in which each of the simultaneously excited slices is assigned a phase and the phase of at least one of the simultaneously excited slices is changed from one repetition to the next, thereby acquiring an MR dataset of a collapsed image in each repetition; performing a spatial registration between the at least two collapsed images and performing motion correction on at least one of the MR datasets of the collapsed images; and reconstructing MR images of the at least two slices from the corrected MR datasets of the collapsed images.