MR Angiography via Radial Acquisition and Phase Analysis
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Solution Overview
Problem
Current methods for generating MR angiography images without contrast agents face challenges such as false activation signals from EKG hardware, arrhythmia issues, and poor correlation of EKG activation signals with arterial or venous phases, especially at distal vascular segments, leading to suboptimal data acquisition.
Innovation Solution
A method involving radial acquisition of MR data in a three-dimensional volume segment using the 'Time of Flight' or TrueFISP approaches, where data is analyzed to associate specific heart beat phases without EKG activation signals, employing the golden angle for k-space scanning and iterative reconstruction to generate MR angiography images, focusing on the arterial phase for clear arterial imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If EKG activation signals are used to guide data acquisition timing, then the arterial or venous phase can be identified, but false activation signals occur from RF signal injection into EKG hardware and arrhythmia leads to wrong phase association
Solution Approach 1:
The patent extracts and removes the EKG activation signal dependency from the data acquisition system. Instead of using external EKG triggers, the method analyzes the MR data itself to determine heart beat phases, thereby eliminating the source of false activation signals and arrhythmia-related errors.
Solution Approach 2:
The MR data acquisition system becomes self-sufficient by analyzing its own data to determine heart beat phases. The method uses the MR data to identify arterial versus venous phases without requiring external EKG hardware, making the system independent of external triggering and its associated problems.
2Measurement precision
If contrast agent injection is used to generate MR angiography images, then clear vascular imaging is achieved, but the method becomes invasive and requires additional hardware and processing
Solution Approach 1:
The system uses the natural physiological properties of blood flow and the MR data itself to generate angiography images without requiring external contrast agents. The method exploits the inherent signal differences between stationary tissue and flowing blood, making the system self-sufficient and eliminating the need for additional contrast injection infrastructure.
Solution Approach 2:
The patent changes the acquisition parameters and data analysis approach to achieve angiography without contrast agents. By modifying the pulse sequence parameters and using specific analysis methods to identify arterial phases, the system achieves vascular imaging through parameter optimization rather than chemical contrast enhancement.
3Adaptability or versatility
If radial acquisition with golden angle is used, then flexible data sampling and interruption capability are achieved, but the data reconstruction complexity increases
Solution Approach 1:
The patent implements dynamic radial sampling where the angle between successive radial lines follows the golden angle approximation. This dynamic sampling scheme allows the acquisition to be interrupted at any point while maintaining uniform coverage of k-space, providing flexibility without requiring fixed predetermined sampling patterns.
Solution Approach 2:
The system uses feedback from the accumulated data to determine when sufficient coverage has been achieved for reconstruction. The iterative reconstruction process continuously evaluates the quality of the reconstructed images and can determine when to stop acquisition, providing adaptive control based on the actual data quality rather than predetermined fixed parameters.
Data Source
AI summary
In the generation of MR angiography images of a predetermined three-dimensional volume segment of a living examination subject using means a magnetic resonance system, MR data in the volume segment are acquired by radial acquisition of k-space. The MR data are analyzed in order to subdivide the MR data into groups, with each group including only the MR data that correspond to a specific heart beat phase of the heat of the examination subject. MR angiography images are generated based only on the MR data of one of these groups.