Dynamic MRI Imaging via EPI Pre-Scan Segmentation
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Solution Overview
Problem
Magnetic Resonance Imaging (MRI) techniques face challenges in achieving high image quality with fast scanning times due to limitations in echo planar imaging (EPI) sequences, leading to prolonged scanning times and reduced temporal resolution, which affects the ability to track dynamic physiological changes effectively.
Innovation Solution
A dynamic imaging method based on EPI sequences that involves pre-scanning to obtain high-quality k-space data, followed by dynamic scanning with multi-channel down-sampled data, using parallel reconstruction with sparsity constraints to generate residual images and combine them with pre-scanned images to produce high-quality dynamic images without extending scanning time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional EPI sequence is used for dynamic imaging, then scanning speed is improved, but image quality deteriorates due to prolonged scanning time and reduced temporal resolution
Solution Approach 1:
The patent segments the imaging process into pre-scan and dynamic scan phases. The pre-scan acquires complete k-space data for high-quality anatomical reference, while the dynamic scan acquires only updated k-space data for temporal changes. This segmentation allows each phase to be optimized independently, resolving the contradiction between scanning speed and image quality.
Solution Approach 2:
The pre-scan is performed as a preliminary action before the dynamic scan to establish a high-quality reference image and k-space data. This preliminary acquisition of complete anatomical information enables the subsequent dynamic scan to focus only on capturing temporal changes, thereby improving both scanning speed and maintaining image quality.
2Measurement precision
If pre-scan with multiple excitations is performed, then image signal-to-noise ratio is improved, but scanning time increases
Solution Approach 1:
The imaging protocol is segmented into a pre-scan phase that performs multiple excitations for high SNR reference image acquisition, and a dynamic scan phase that uses fewer excitations for time-sensitive dynamic imaging. This segmentation allows the high SNR requirement to be met only when necessary, while reducing scanning time during dynamic acquisition.
Solution Approach 2:
The pre-scan performs multiple excitations (excessive action) to ensure high signal-to-noise ratio for the reference image, while the dynamic scan uses partial action with fewer excitations since it only needs to capture temporal changes. This differentiated approach optimizes the balance between SNR and scanning time for different imaging phases.
3Speed
If dynamic scan with down-sampled k-space data is used, then scanning speed is improved, but image sharpness deteriorates
Solution Approach 1:
The patent merges the pre-scan k-space data with the dynamic scan down-sampled k-space data through addition in the image domain. The pre-scan provides high-resolution anatomical structure information, while the dynamic scan provides temporal update information. This merging allows the dynamic images to maintain sharpness from the pre-scan while capturing temporal changes from the dynamic scan.
Solution Approach 2:
The pre-scan image acts as an intermediary that carries the high-frequency anatomical detail information. By adding the residual dynamic information to this intermediary reference image, the final dynamic images maintain both the sharpness from the pre-scan and the temporal accuracy from the dynamic scan, resolving the contradiction between speed and sharpness.
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 signal-to-noise ratio and reduces distortion without requiring high hardware upgrades, maintaining high image sharpness and temporal resolution, allowing for continuous tracking of physiological changes.
Implementation Method 1
hydrogen protons in a human body are excited by a radio-frequency excitation based on a magnetic resonance phenomenon
Implementation Method 2
position encoding is performed with gradient magnetic fields
Data Source
AI summary
Methods, devices, systems and apparatus for dynamic imaging based on echo planar imaging (EPI) sequence are provided. In one aspect, a method includes: obtaining first pre-scanned k-space data by performing a pre-scan for a subject based on a first EPI sequence and pre-scanning parameters, obtaining a pre-scanned image and second pre-scanned k-space data according to the first pre-scanned k-space data, performing a dynamic scan for the subject based on a second EPI sequence and dynamic scanning parameters to generate dynamically-scanned k-space data associated with each of a plurality of dynamic periods in the dynamic scan, and for each of the dynamic periods, generating a residual image according to the dynamically-scanned k-space data of the dynamic period and the second pre-scanned k-space data, and adding the pre-scanned image and the residual image to obtain a dynamic image of the dynamic period.