MRI Cardiac Phase Setting for Arterial Venous Flow Separation
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Solution Overview
Problem
In magnetic resonance imaging (MRI) using the ECG-gating method, determining the optimal delay time for distinguishing between arterial and venous blood flow in the legs is cumbersome and often not suitable for all imaging conditions, making it difficult for operators to obtain precise images.
Innovation Solution
A magnetic resonance imaging system and method that includes a prep scan section for acquiring echo signals at multiple cardiac time phases, a section for generating prep images, and a cardiac time phase setting section that allows operators to specify and set optimal cardiac time phases for imaging, enabling the generation of differential images that help determine suitable delay times automatically or with reduced operator burden.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the operator manually determines delay time based on ECG-prep scan images, then the imaging process can be performed, but the operator burden increases and the precision of delay time setting decreases
Solution Approach 1:
The system performs automatic delay time determination through the cardiac time phase determination section, which analyzes prep images and ECG signals autonomously to calculate optimal delay times without requiring manual operator intervention. This self-service mechanism resolves the contradiction by eliminating the need for operator burden while maintaining high precision through automated image analysis and signal processing.
Solution Approach 2:
The system changes the parameter determination method from manual visual assessment to automated calculation based on ECG signal timing. The cardiac time phase determination section computes delay times by analyzing the temporal relationship between ECG R-wave triggers and blood flow imaging data, transforming the delay time parameter from a manually estimated value to a precisely calculated parameter based on physiological signal timing.
2Reliability
If manual delay time determination is used, then flexibility in handling different imaging conditions is maintained, but the precision and consistency of delay time setting across different cases deteriorates
Solution Approach 1:
The system implements feedback through the cardiac time phase determination section, which continuously analyzes the relationship between ECG signals and blood flow imaging data to automatically adjust and determine optimal delay times. This feedback mechanism ensures reliable and consistent delay time settings across different imaging conditions by using actual physiological signal timing rather than manual estimation, thereby improving reliability without requiring complex manual intervention protocols.
3Manufacturing precision
If the phase encoding direction is set in the blood vessel running direction, then spatial resolution is improved, but artifacts are superimposed on blood vessels making flow-void extraction difficult
Solution Approach 1:
The system dynamically adjusts the phase encoding direction based on the specific imaging requirements and blood vessel orientation. Rather than using a fixed encoding direction, the system can adaptively select optimal encoding directions to minimize artifacts while maintaining spatial resolution, resolving the contradiction by making the encoding parameters dynamic rather than static.
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 simplifies the setting of delay times, reduces operator burden, and improves the precision of distinguishing between arterial and venous blood flow in MRI images, particularly in the legs, by automatically determining suitable delay times based on image analysis.
Implementation Method 1
magnetic resonance imaging system and magnetic resonance imaging method for imaging a subject to be examined
Implementation Method 2
The arterial signal can be further suppressed by a flow-dephasing effect when a readout and encoding direction is set in a blood vessel running direction
Data Source
AI summary
An MRI prep scan acquires plural sets of echo signals at a plurality of cardiac time phases which are mutually different from each other for each slice and used to generate a plurality of respectively corresponding prep images. Reference information is acquired and displayed for determining a first cardiac time phase and a second cardiac time phase on the basis of the prep images. The first and second cardiac time phases are set in response to an operator's specification. An imaging scan section for acquiring imaging echo signals by performing an imaging scan is performed upon each of the first and second cardiac time phases to acquire imaging echo signals. A first image is generated based on an echo signal of the first cardiac time phase and a second image is generated based on an echo signal of the second cardiac time phase. A differential image is acquired by calculating a difference between the first image and the second image.