Vector Cardiogram Synchronization for MRI Heart Imaging
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Solution Overview
Problem
Magnetic resonance imaging (MRI) synchronization with heart cyclic movement is challenged by noise sources like magneto-hydrodynamic effects and magnetic gradient field distortions, leading to errors in image acquisition, especially during different breathing phases.
Innovation Solution
Adapting the discriminating function and reference function based on the subject's breathing status by modifying the angular relationship between the electrical axis and instantaneous vector of the vector cardiogram to improve synchronization of MRI signal acquisition with heart movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If synchronization is conducted with respect to the prominent R-wave of the QRS-complex, then each portion of the magnetic resonance image is acquired at the same phase of the cardiac cycle, but noise sources such as magneto-hydrodynamic effects and magnetic gradient field distortions give rise to synchronization issues
Solution Approach 1:
The invention changes the parameter used for synchronization from the traditional R-wave detection to the vector cardiogram's instantaneous vector direction. By using the angular relationship between the electrical axis and the instantaneous vector, the system achieves more reliable synchronization that is less susceptible to noise from magneto-hydrodynamic effects and magnetic gradient field distortions.
Solution Approach 2:
The invention replaces the mechanical/electrical signal-based R-wave detection with a vector-based approach. The vector cardiogram provides directional information about cardiac electrical activity, allowing synchronization to be based on the orientation of the instantaneous vector relative to the electrical axis, which is more robust against electromagnetic noise.
2Ease of manufacture
If a fixed threshold reference function is used for determining acquisition periods, then the method is simple to implement, but the number of erroneous acquisition periods increases during different breathing phases
Solution Approach 1:
The invention introduces dynamic adaptation of the reference function based on breathing status. Instead of using a fixed threshold, the reference function is adjusted according to the subject's breathing phase, which accounts for the physiological changes that occur during respiration. This dynamic approach maintains implementation simplicity while significantly improving the accuracy of acquisition period determination.
Solution Approach 2:
The system incorporates feedback by monitoring breathing status and using this information to adapt the reference function. The breathing status detection provides feedback that allows the system to adjust its synchronization parameters in real-time, reducing erroneous acquisition periods while maintaining ease of implementation through automated adaptation.
Data Source
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AI summary
A method of imaging, by means of magnetic resonance, at least a portion of a human or animal subject of interest (20) positioned in a static magnetic field, the method comprising: - taking measurements of electrocardiogram data; - generate vector cardiogram data from the electrocardiogram data; - determining at least one parameter of an acquisition period of acquiring magnetic resonance signals from the vector cardiogram data in order to synchronize measurement of magnetic resonance signals to a cyclic movement of the heart of the subject of interest (20); wherein the at least one parameter of the acquisition period is determined from an actual value of a discriminating function and a predetermined reference function, wherein for determining the at least one parameter of the acquisition period, a step of adapting at least one of the discriminating function and the predetermined reference function is executed, dependent on a breathing status of the human or animal subject of interest (20); and - a magnetic resonance imaging system (10) for acquisition of images of at least a portion of a human or animal subject of interest (20), synchronized to a cyclic movement of the heart of the subject of interest (20), comprising: - a control unit (28) for controlling functions of the magnetic resonance imaging system (10); - an image processing unit (34) provided for processing acquired magnetic resonance signals; - an electrocardiogram device (36) for taking measurements of electrocardiogram data of the heart of the subject of interest (20); - a synchronization unit (40) coupled to the electrocardiogram device (36) and configured for determining at least one parameter of an acquisition period from the vector cardiogram data, wherein the synchronization unit (40) is configured to provide trigger signals (60) indicative of the determined at least one parameter of the acquisition period to the control unit (28); and wherein the synchronization unit (40) is configured to adapt at least one of the discriminating function and the predetermined reference function, dependent on a breathing status of the human or animal subject of interest (20).