Non-metallic Piston Actuator for MRE Shear Wave Generation
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Solution Overview
Problem
Current magnetic resonance elastography (MRE) devices face challenges in efficiently producing shear waves with high amplitude and fidelity, particularly for imaging the brain, due to the skull and cerebrospinal fluid, which leads to discomfort and distortion in elasticity maps, and existing actuators often result in 'jack-hammer' effects and reduced vibration amplitudes to maintain comfort.
Innovation Solution
A non-metallic MRE actuator comprising a spring-loaded plastic piston with a restorative device, connected to an air, hydraulic, or mechanical source, providing a non-metallic interface for vibrating tissue, ensuring tight coupling and minimizing higher harmonics, thus allowing for larger amplitude vibrations without discomfort and maintaining single-frequency fidelity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MRE actuators are used to vibrate tissue, then shear waves can be produced, but the skull and cerebrospinal fluid cause discomfort and distortion in elasticity maps
Solution Approach 1:
The patent introduces a non-metallic piston as an intermediary element between the actuator and the tissue. This piston serves as a mediator that transmits vibrations more effectively through the skull and cerebrospinal fluid while reducing discomfort. The piston's non-metallic construction allows it to be used with MRI scanners while its mechanical properties enable it to couple vibrations to the tissue more efficiently, resolving the contradiction between achieving accurate elasticity maps and minimizing discomfort.
Solution Approach 2:
The patent changes the material parameter of the piston from metallic to non-metallic, which allows the actuator to be used with MRI scanners. This parameter change enables the system to maintain vibration amplitude while reducing the harmful effects of skull and cerebrospinal fluid interference, thereby improving both the accuracy of elasticity maps and patient comfort.
2Measurement precision
If vibration amplitude is increased to improve shear wave production, then higher fidelity images are achieved, but discomfort and jack-hammer effects increase
Solution Approach 1:
The non-metallic piston acts as an intermediary that decouples the direct transmission of high-amplitude vibrations to the tissue, reducing jack-hammer effects and discomfort while still enabling sufficient vibration amplitude for high-fidelity shear wave detection. The piston's mechanical properties allow it to transmit vibrations effectively without the harmful effects associated with direct high-amplitude actuation.
3Strength
If metallic actuators are used for MRE, then structural strength is achieved, but MRI compatibility is lost due to metal interference
Solution Approach 1:
The patent changes the material parameter of the actuator components from metallic to non-metallic, specifically using non-metallic pistons and housing. This parameter change eliminates MRI interference while maintaining sufficient structural strength through the design of the non-metallic components. The non-metallic materials used are specifically selected to provide the necessary mechanical properties without interfering with MRI fields.
4Object-affected harmful factors
If non-metallic materials are used for MRI compatibility, then MRI interference is eliminated, but structural strength may be reduced
Solution Approach 1:
The patent employs composite material construction for the actuator components, combining non-metallic materials with appropriate structural properties. The non-metallic piston and housing are designed to provide sufficient structural strength for actuation while maintaining MRI compatibility. The composite design allows optimization of both material properties for strength and properties for MRI compatibility.
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
The solution enables high-fidelity, high-amplitude shear wave production with minimal discomfort, improving the accuracy and clarity of shear modulus images by reducing unwanted harmonics and ensuring vibrations are primarily at the intended frequency, enhancing the diagnostic capabilities of MRE.
Implementation Method 1
a restorative device that connects the closed end of the body to the opposite end of the piston and that produces a restoring force on the piston when the piston is displaced relative to the body
Implementation Method 2
a first non-metallic connector on the body that provides the body with a connection to an air, hydraulic or mechanical source of pressure that vibrates the piston
Implementation Method 3
a non-metallic interface located on the end of the piston that protrudes from the body, where the interface provides a contact area with a subject
Data Source
AI summary
Disclosed are piston actuator devices and their uses for magnetic resonance elastography (MRE).