GRE Reference Scan for SMS MRI Artifact Correction
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Solution Overview
Problem
Conventional magnetic resonance imaging methods, particularly Simultaneous Multislice (SMS) imaging, require time-consuming preparation and reference scans for calibration and artifact correction, which significantly prolong the examination time due to the need for EPI-based reference scans.
Innovation Solution
The method employs a GRE or RARE-based reference scan for rapid data acquisition and a dedicated EPI-based phase correction scan to obtain slice-specific GRAPPA kernels, allowing for the separation and correction of collapsed slice data, thereby reducing the overall examination time by eliminating the need for conventional EPI-based reference scans.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional EPI-based reference scans are used for calibration and artifact correction in SMS imaging, then image precision and artifact correction are maintained, but examination time is significantly prolonged
Solution Approach 1:
The patent segments the reference scan into two distinct parts: a GRE-based scan for GRAPPA kernel calibration and an EPI-based phase correction scan for ghost artifact correction. This segmentation allows each type of data to be acquired using the most appropriate sequence, optimizing both speed and accuracy while reducing total calibration time.
Solution Approach 2:
The patent changes the acquisition sequence parameter from conventional EPI-based reference scanning to a hybrid approach using GRE sequences for calibration. This parameter change exploits the faster acquisition speed of GRE sequences for the calibration portion, significantly reducing the time-consuming reference scan while maintaining image quality through subsequent EPI-based phase correction.
2Productivity
If GRE or RARE-based reference scans are used instead of conventional EPI-based reference scans, then data acquisition speed is increased and examination time is reduced, but the ability to correct ghost artifacts may be compromised
Solution Approach 1:
The patent merges two different acquisition approaches into a unified calibration process: GRE-based GRAPPA calibration and EPI-based phase correction. By combining these methods, the system achieves both fast data acquisition (through GRE) and reliable ghost artifact correction (through EPI phase correction), resolving the contradiction between speed and reliability.
Solution Approach 2:
The patent introduces an intermediary EPI-based phase correction scan that bridges the gap between the fast GRE-based calibration and the need for accurate ghost artifact correction. This intermediary step uses the phase information from EPI sequences to correct artifacts without requiring a full conventional EPI-based reference scan, thus maintaining reliability while improving speed.
Data Source
AI summary
In a method and system, a reference dataset is recorded using a reference scan based on a GRE or RA RT sequence. A correction dataset is also recorded using a phase correction scan based on a non-phase-encoding EPI sequence. A measurement dataset is recorded using an SMS sequence. Slice-specific GRAPPA kernels are determined from the reference dataset and magnetic resonance images are created by a slice GRAPPA method. Data of the measurement dataset belonging to different slices is separated from one another using the slice-specific GRAPPA kernels and N/2 ghost artifacts are corrected using the correction dataset.