Inertial Vibration Probe for 2D Viscoelastic Tissue Mapping
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Solution Overview
Problem
Existing technologies for measuring tissue viscoelastic properties, such as shear wave elastography, face challenges in achieving efficient 2D tissue mapping due to ergonomic issues, high energy consumption, and limitations in depth penetration, particularly in the context of liver fibrosis evaluation.
Innovation Solution
A 2D pulse elastography system using a probe with a network of transducers and an inertial vibration exciter, where the moving part of the exciter represents 5-25% of the probe's mass, operates at a resonant frequency, and includes a return spring with a stiffness coefficient between 300 kg.s^2 and 50,000 kg.s^2, allowing efficient shear wave generation with minimal energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an electrodynamic actuator is used to vibrate the transducer for shear wave generation, then efficient mechanical energy transmission to the tissue is achieved, but the device becomes incompatible with 2D tissue mapping due to the large size of the transducer array and cable harness
Solution Approach 1:
The device is segmented into two separate components: a compact handheld probe containing only the ultrasonic transducer array for 2D imaging, and an external mechanical excitation system with the electrodynamic actuator and vibrator. This segmentation allows the transducer array to remain small and maneuverable while the actuator provides sufficient mechanical energy transmission capability.
Solution Approach 2:
The mechanical excitation function is extracted from the probe and placed in an external device. The probe contains only the ultrasonic transducer array, which is connected to the external excitation system via a flexible cable. This extraction enables the probe to be compact and suitable for 2D mapping while the external device houses the bulky electrodynamic actuator.
2Adaptability or versatility
If rods are positioned on either side of the transduction elements for mechanical excitation, then 2D mapping capability is achieved, but the system width becomes incompatible with liver exploration between ribs and creates disinfection problems
Solution Approach 1:
The mechanical excitation function is separated from the probe body and placed in an external device. The probe itself contains only the flexible transducer array, which can be maneuvered into the intercostal space for liver exploration. The external excitation device operates independently and connects to the probe via cable, avoiding the need for wide positioning of rods.
Solution Approach 2:
The excitation mechanism transitions from a wide lateral arrangement (rods on either side) to a longitudinal arrangement where the flexible cable connects the external actuator to the probe along the length of the probe. This dimensional change allows the probe to maintain a narrow profile suitable for intercostal access while still providing 2D mapping capability.
3Power
If the moving part mass is increased to generate sufficient shear wave power, then deep tissue penetration is achieved, but the probe size and weight increase, reducing maneuverability
Solution Approach 1:
The heavy inertial mass required for shear wave generation is extracted from the probe and placed in the external excitation device. The probe contains only lightweight ultrasonic transducer elements, while the external device houses the massive electrodynamic actuator and vibrator components that generate the mechanical excitation forces.
Solution Approach 2:
A flexible cable acts as an intermediary, transmitting mechanical vibrations from the external actuator to the compact probe. This allows the probe to remain lightweight and maneuverable while still receiving sufficient mechanical energy transmission capability from the external device through the cable connection.
4Device complexity
If acoustic radiation pressure is used to generate shear waves, then the probe structure is simplified, but the shear wave amplitude is low and depth penetration is limited
Solution Approach 1:
The invention merges the advantages of both acoustic and mechanical approaches by combining a compact ultrasonic transducer array (for imaging and acoustic radiation pressure) with an external mechanical excitation system. The mechanical excitation provides high-amplitude shear waves for deep penetration, while the ultrasonic array provides imaging capability and supplementary acoustic radiation pressure for enhanced shear wave generation.
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 system enables effective 2D viscoelastic property measurement with reduced energy use, compact size, and ease of disinfection, suitable for battery operation and maneuverability, while maintaining sufficient shear wave power for deep tissue penetration.
Implementation Method 1
at least one inertial vibration exciter for the emission of at least one low-frequency elastic wave, said and at least one exciter including: a fixed part mechanically secured to the network of transducers, a mobile part capable of moving freely relative to the fixed part to produce vibrations in order to generate the low-frequency elastic wave
Implementation Method 2
a network of transducers, mechanically secured to the housing, for the emission of high-frequency ultrasonic waves
Implementation Method 3
for the emission of high-frequency ultrasonic waves and the reception of acoustic echoes
Implementation Method 4
at least one return spring extending between the fixed part and the mobile part, and in This that the stiffness coefficient of said and at least one return spring is between 300 kg.s^2 and 50,000 kg.s^2
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The present invention relates to a probe for measuring the viscoelastic properties of a human or animal medium of interest, such as a liver, said measurement consisting of: - generating at least one low-frequency elastic wave in the medium of interest, - simultaneously with the generation of the low-frequency wave: o emitting high-frequency ultrasonic waves, and o receiving acoustic echoes due to the reflections of the ultrasonic waves in the medium of interest, the probe comprising: - a housing (31), - a transducer array (33) for emitting high-frequency ultrasonic waves and receiving acoustic echoes, characterised in that the probe (3) further comprises at least one inertial vibration exciter (34) including: - a fixed part (341) mechanically integral with the transducer array (33), - a mobile part (342) capable of moving relative to the fixed part to produce vibrations in order to generate the low-frequency elastic wave.