Rotational Eccentric-Mass Position Feedback for MRE Scans
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Solution Overview
Problem
Existing magnetic resonance elastography (MRE) systems using gravitational transducers face challenges in achieving stability and synchronization of mechanical excitation with MRI systems, particularly affecting the angular position of the eccentric mass, which impacts the reliability and stability of measurement results.
Innovation Solution
A method and system for synchronizing the rotational eccentric mass of a gravitational transducer with an MRE scan by adjusting the rotational speed based on reference positions and comparing current positions with theoretically expected positions, using a stepper motor and motor controller to ensure precise synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a gravitational transducer with rotational eccentric mass is used for MRE excitation, then linearity is improved and parasitic harmonics are reduced, but stability and synchronization of the mechanical excitation with the MRI system deteriorates
Solution Approach 1:
The patent implements a feedback control system where the actual rotational position of the eccentric mass is continuously measured and compared with the theoretically expected reference position. Based on this comparison, the rotational speed is dynamically adjusted to minimize position deviations, thereby maintaining stable and synchronized mechanical excitation throughout the MRE acquisition process.
Solution Approach 2:
The patent replaces a purely mechanical speed control system with an integrated system that combines mechanical rotation, optical or magnetic position sensing, and electronic feedback control. This substitution allows for precise measurement and adjustment of rotational position, transforming the system from open-loop to closed-loop control.
2Productivity
If the rotational speed of the eccentric mass is increased to match acquisition frequency, then synchronization with MRI system is improved, but stability of angular position deteriorates
Solution Approach 1:
The patent makes the rotational speed dynamic rather than fixed. The speed is continuously adjusted based on real-time position feedback to maintain synchronization with the MRI acquisition sequence. This dynamic adaptation allows the system to compensate for variations and maintain both high synchronization and angular position stability.
Solution Approach 2:
The patent changes the operational parameters of the rotational system by continuously adjusting the rotational speed based on the comparison between actual and reference positions. This parameter adjustment ensures that the eccentric mass remains synchronized with the MRI acquisition while maintaining stable angular positioning throughout the scanning process.
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 stabilizes the gravitational transducer, ensuring reliable and stable mechanical excitation synchronized with the MRI system, thereby improving the accuracy and reliability of MRE measurements.
Implementation Method 1
The gravitational transducer is based on a rotational eccentric mass, wherein the rotation of the eccentric mass is used to excite vibrations
Data Source
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AI summary
A method for synchronizing a rotational eccentric mass of a gravitational transducer used for a magnetic resonance elastography acquisition with a corresponding magnetic resonance elastography scan carried out by a magnetic resonance imaging system, wherein the rotation of the eccentric mass is driven by a shaft, the method comprising the steps: (a) starting the rotation of the eccentric mass at a set vibration frequency and the magnetic resonance elastography scan at a set acquisition frequency; (b) determining the rotational position of the shaft; (c) defining the determined rotational position as first reference position; (d) calculating further reference positions, wherein the further reference positions may be the same as the first reference position, or may alternate between several positions; (e) at the start time of each subsequent acquisition period, determining the current rotational position of the shaft; (f) comparing the determined current rotational position with the theoretically expected reference position and decreasing or increasing the rotational speed of the rotational eccentric mass based on the comparison.