CN109875504B - Method for non-invasively measuring corneal viscoelasticity based on jet optical coherence elastography technology - Google Patents
Method for non-invasively measuring corneal viscoelasticity based on jet optical coherence elastography technology Download PDFInfo
- Publication number
- CN109875504B CN109875504B CN201910034893.4A CN201910034893A CN109875504B CN 109875504 B CN109875504 B CN 109875504B CN 201910034893 A CN201910034893 A CN 201910034893A CN 109875504 B CN109875504 B CN 109875504B
- Authority
- CN
- China
- Prior art keywords
- elastic wave
- elastic
- cornea
- corneal
- phs
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Landscapes
- Eye Examination Apparatus (AREA)
Abstract
A method for non-invasively measuring the corneal viscoelasticity based on an air-jet optical coherence elastography technology is characterized in that pulsed airflow is used for inducing the cornea to deform, the propagation condition of an elastic wave in the cornea is detected through Phs-OCT, and besides the propagation speed, the central wavelength of the elastic wave and the energy attenuation coefficient in the propagation process are extracted, so that the corneal tissue viscoelasticity is estimated. The method fully utilizes the propagation characteristics of the elastic waves, not only utilizes the propagation speed of the elastic waves to estimate the elastic modulus of the soft tissue, but also comprehensively utilizes the energy attenuation coefficient and the central angle frequency of the elastic waves to extract the viscosity coefficient of the soft tissue, and utilizes the energy attenuation characteristics of the elastic waves to extract the energy attenuation coefficient of the elastic waves through curve fitting; meanwhile, two-dimensional Fourier transform is carried out on the phase information of different positions at different moments to obtain spatial frequency spectrum information, so that the central angle frequency of the elastic wave is extracted; the elastic wave energy attenuation coefficient and the central angular frequency are combined together to estimate the soft tissue viscosity coefficient.
Description
Technical Field
The invention particularly relates to the technical field of optical coherent elastography, and particularly relates to a method for non-invasively measuring corneal viscoelasticity based on an air jet type optical coherent elastography technology.
Background
The corneal tissue is a viscoelastic material, has two characteristics of viscosity and elasticity, and can be characterized by biomechanical performance parameters such as elastic modulus, viscosity coefficient and the like. However, the existing research finds that the mechanical properties of the cornea can assist in early diagnosis of certain ophthalmic diseases (such as keratoconus, Fuchs corneal degeneration and the like) and guide to carry out corneal related operations (such as corneal refractive operation, corneal crosslinking operation and the like).
The Optical Coherence Elastography (OCE) is a technique based on an Optical Coherence Tomography (OCT) and uses biological parameters such as elastic modulus, shear modulus, and viscosity coefficient of soft tissue as an imaging target. Because the diameter of the cornea of a human eye is about 11mm, the central thickness of the cornea is only 0.52mm, and the OCE keeps the advantages of high resolution, non-invasive property, high scanning speed and the like of OCT, compared with other elastic technologies such as Brillouin optical microscope (CBM), Ultrasonic Elastography (UE), Magnetic Resonance Elastography (MRE) and the like, the method can image the corneal tissue in real time and high precision, and has great clinical application prospect in the aspect of corneal biomechanics in vivo measurement.
From the structural aspect, the OCE system consists of three parts, namely a mechanical loading device, a tissue response reaction and a motion detection system. While tissue response and motion detection systems depend on the type of mechanical loading. The types of mechanical loading commonly used today are classified into 3 forms of static, vibratory and pulsed excitation. The OCE system adopts a pulse excitation mode to cause the biological tissue to generate shear wave propagation, and the propagation condition of the shear wave is detected through Phase sensitive OCT (Phs-OCT), so as to obtain the biomechanical property of the tissue, and the tissue can enter a clinical application stage at the fastest speed.
Pulse excitation is currently classified into Piezoelectric ceramic excitation (PZT), ultrasonic excitation (ARF), Air excitation (Air puff), laser excitation (Pulsed laser excitation), and Air-coupled ultrasonic excitation (a μ T). The piezoelectric ceramic excitation is in a contact type, so that the patient is easy to feel uncomfortable; ultrasonic excitation requires a water bath environment, and is not suitable for clinical implementation; laser may have damage to eye tissues, and lacks safety; air-coupled ultrasound overcomes the drawback of traditional ultrasound that needs to be propagated through a water bath environment, but this technology is just emerging, still in the development stage and security remains to be verified. Air excitation is a safe and effective non-contact excitation mode among the above excitation modes, and is easy to popularize and apply clinically.
(1) OCE based on amplitude contrast:
the teaching team of Maciej Wojtkowski of the Bondyland Cocini university utilizes pulse airflow to apply excitation to the cornea, and detects the deformation process of the cornea in real time through SSOCT, so as to obtain the variation of the whole axial (A-scan) structure of the cornea at a certain position along with time. If the amount of corneal deformation is large, it indicates that the elastic modulus of the corneal tissue is small. The method is based on a structural OCT image, displacement resolution is limited, and the reflected elastic modulus of corneal tissue is a relative value. (reference: Association of corn dynamics with high-speed sweet soil Optical Coherence combined with an air pump system)
(2) Elastic wave-based OCE:
the group of Kirill V.Larin professor of Houston university, USA, first realized OCE of cornea of in vivo mouse, which also induced the deformation of cornea by applying excitation to cornea with pulse airflow, but detected the deformation of cornea tissue by Phase sensitive OCT (Phs-OCT), the precision of which could reach nanometer level and is much higher than the axial resolution (micron level) of structure OCT, could detect the elastic wave propagation in cornea tissue, and according to the relationship between the elastic wave propagation speed and the elastic modulus of tissue, that is, the relationship between the elastic wave propagation speed and the elastic modulus of tissue
Wherein E is the elastic modulus, ρ is the soft tissue density, ρ is the Poisson's ratio of the soft tissue, and c is the elastic wave velocity.
The method can obtain the elastic modulus of the corneal tissue within a certain range, but cannot reflect the viscosity coefficient of the corneal tissue. (from journal articles "Dynamic optical coherence tomography measures of elastic wave propagation in tissue-differentiation vectors and motion corn in vivo")
(3) Resonance frequency based OCE:
the Chen faith professor team of the European school of California university uses acoustic radiation force with different excitation frequencies to induce the soft tissue to generate deformation, and Phs-OCT is used for detecting the deformation of the soft tissue, and the deformation of the soft tissue reaches the maximum value when the excitation frequency is consistent with the natural frequency of the soft tissue; meanwhile, they found that the elastic modulus of soft tissue and the natural frequency satisfy the following relationship:
λ＝-γ/2m
wherein E is the elastic modulus, k is the elastic coefficient, L is the thickness of the soft tissue, S is the area of the soft tissue, μ is the natural frequency, λ is the attenuation coefficient of the soft tissue, m is the mass of the soft tissue, and γ is the viscosity coefficient of the soft tissue. Therefore, the elastic modulus of the soft tissue can be obtained by the method, but vibration excitation with different frequencies is needed to obtain the natural frequency of the soft tissue, the operation is complicated, and meanwhile, the method ignores the viscosity coefficient, and finally only the elastic modulus of the soft tissue can be estimated. (from journal articles "resource environmental radiation for optical coherence tomography")
Disclosure of Invention
The invention provides a method for non-invasively measuring corneal viscoelasticity based on a jet optical coherence elastography technology, aiming at solving the defects that the viscosity coefficient of soft tissue is far smaller than the elastic modulus and is ignored, and the elastic modulus of the soft tissue can only be estimated finally and the biomechanical performance of the soft tissue cannot be comprehensively reflected in the existing OCE whether based on amplitude contrast, elastic wave or resonance frequency.
The technical solution adopted by the invention is as follows: a method for non-invasively measuring the corneal viscoelasticity based on a jet optical coherence elastography technology comprises the following steps:
(1) constructing and integrating a Phs-OCT system: integrating an air injection device and a Phs-OCT system to ensure that air pulse and Phs-OCT detection need to simultaneously act on corneal tissues, and adopting an oblique incidence integration mode, namely forming an included angle between an air injection emission probe and a long axis of a Phs-OCT scanning probe, wherein at a signal control layer, Phs-OCT drives a galvanometer working signal to be used as a trigger signal of a valve switch of the air injection device to ensure that image acquisition and air pulse emission are synchronous;
(2) the doppler phase resolution algorithm applies: the method comprises the following steps of obtaining interference spectrum intensity I (lambda) by a balance detector, carrying out spectrum correction and direct current item removal, enabling the center frequency to be from a carrier wave to zero, converting the interference spectrum intensity I (lambda) into an interference signal I (k) with wave number k as a variable, and carrying out fast discrete Fourier transform (FFT) to obtain a complex value signal with depth z as a variable, namely an expression (4-1):
and performing cross correlation on two adjacent A-lines to obtain phase information, wherein the phase information is represented by the following formula (4-2):
by comparing the change of the phase information, the sensitivity of the system to the deformation detection of the sample is improved.
(3) Constructing a cornea biomechanical model: the common Kelvin-Voigt model is used to characterize the relationship between the elasticity and viscosity of corneal tissue, i.e. the two are in parallel relationship,
from the viscoelastic relationship in the Kelvin-Voigt model, the following formula (4-3) can be obtained,
μ＝μ1+iωζ (4-3)；
wherein μ is the coefficient of viscoelasticity, μ1For shear modulus, ω is the angular frequency of the elastic wave, and ζ is the shear viscosity; but is elasticModulus E and shear modulus μ1The relationship of (A) is as follows (4-4),
E＝2(1+υ)μ1 (4-4)；
propagation rate C (omega) and shear modulus mu of elastic wave1The relationship between the angular frequency ω and the shear viscosity ζ is as follows (4 to 5):
where ρ is the soft tissue density, when the soft tissue shear viscosity ζ is much less than the shear modulus μ1Then, the above formula can be simplified to formula (4-6),
and the energy attenuation coefficient alpha (omega) in the elastic wave propagation process satisfies the following formula (4-7):
(4) corneal viscoelasticity estimation: according to a cornea biomechanics mathematical model, under the condition that cornea tissue density rho and Poisson ratio upsilon are certain, the premise of obtaining the elastic modulus E and the shear viscosity zeta is to clearly determine the elastic wave velocity C (omega), the central angular frequency omega of an elastic wave and the elastic wave energy attenuation coefficient alpha (omega);
assuming that the scan parameters of the OCE are set as follows, the M-mode value in the M-B mode is set as M, the B-mode value is set as n, and the time interval between adjacent A-lines is T, according to the Phs-OCT algorithm, the phase corresponding to the jth A-line at the ith bit point on the cornea is
Then take the maximum phase of the ith position
To characterize the propagation of elastic waves, then
Satisfies the following relational expression (4-8):
where the max function is taken to be the maximum and m is the number of A-lines scanned in total at the ith position, and will be
The corresponding j is defined as mji(z) the position of the ith position is xiSince the corneal tissue cross section is uniform over a local area, the elastic modulus E remains unchanged; will mji(z) as abscissa, position xiAs ordinate, plotted as mji(z)-xiA scatter diagram, and the slope a can be obtained by using a least square method;
the elastic wave velocity C (ω) can be expressed by the formula (4-9):
the energy Q of the elastic wave is proportional to the square of its amplitude, which is proportional to the phase, and therefore the energy Q of the elastic wave is proportional to the square of the phase, i.e. equation (4-10),
and elastic wave energy Q at the i-th siteiSatisfies the following relational expression (4-11):
wherein Q0Is the initial elastic wave energy, is a constant;
by using
To characterize elastic wave energy QiThen it is known
And xiObtaining the attenuation coefficient alpha (omega) through curve fitting;
and the central angular frequency omega can pass through the pair
Obtained by performing spectral analysis, i.e. on
Two-dimensional Fourier transform (FFT2) is performed to obtain spectrum information SPk,fAs shown in formulas (4-12),
where k is the wave number and f is the frequency. Get SPk,fF corresponding to the maximum value is the center frequency fcThen, the formula (4-13) can be obtained,
ω＝2πfc (4-13)；
from the above, the elastic wave velocity C (ω), the central angular frequency ω of the elastic wave, and the elastic wave energy attenuation coefficient α (ω) are sequentially obtained, and the elastic modulus E and the shear viscosity ζ of the corneal tissue are estimated.
The Phs-OCT system adopts an M-B scanning mode, wherein the M mode refers to that a certain specific position of a cornea is subjected to A-line scanning for multiple times to acquire a dynamic change process of displacement along with time; the B mode refers to two-dimensional tomography of the cornea, and the displacement change conditions of a plurality of positions of the cornea at a certain time can be obtained by adopting the M-B mode, so that the propagation condition of elastic waves in the cornea tissue is reflected.
The invention has the beneficial effects that: the invention provides a method for non-invasively measuring the corneal viscoelasticity based on an air-jet optical coherence elastography technology, which utilizes pulse airflow to induce the cornea to deform, detects the propagation condition of an elastic wave in the cornea through Phs-OCT, extracts the central wavelength of the elastic wave and the energy attenuation coefficient in the propagation process besides the propagation speed, and further estimates the viscoelasticity of corneal tissues. The method fully utilizes the propagation characteristics of the elastic waves, not only utilizes the propagation speed of the elastic waves to estimate the elastic modulus of the soft tissue, but also comprehensively utilizes the energy attenuation coefficient and the central angle frequency of the elastic waves to extract the viscosity coefficient of the soft tissue, and utilizes the energy attenuation characteristics of the elastic waves to extract the energy attenuation coefficient of the elastic waves through curve fitting; meanwhile, two-dimensional Fourier transform is carried out on the phase information of different positions at different moments to obtain spatial frequency spectrum information, so that the central angle frequency of the elastic wave is extracted; the elastic wave energy attenuation coefficient and the central angular frequency are combined together to estimate the soft tissue viscosity coefficient.
Drawings
FIG. 1 is a structural diagram of an experimental apparatus based on jet optical coherence elastography.
In the figure, 1-1060nm sweep laser source, 2-90/10 optical fiber coupler, 3-circulator, 4-optical fiber collimator, 5-focusing lens, 6-plane reflector, 7-circulator, 8-optical fiber collimator, 9-one-dimensional scanning galvanometer, 10-focusing lens, 11-sample, 12-50/50 optical fiber coupler, 13-balance detector, 14-computer host, 15-air injection device signal controller, 16-air injection device electronic valve, 17-air injection nozzle, 18-air storage tank and 19-light beam.
Detailed Description
The invention is further explained by combining fig. 1, and the invention is based on the jet optical coherence elastography technology to non-invasively measure the corneal viscoelasticity, and mainly comprises the steps of building a Phs-OCT system, integrating a jet device and the Phs-OCT system, constructing a corneal biomechanical mathematical model and estimating the corneal viscoelasticity.
(1) The method comprises the following steps of (1) building a Phs-OCT system, and integrating an air injection device and the Phs-OCT system: the air pulse and the Phs-OCT detection need to act on corneal tissues at the same time, so that the synchronous integration of the air injection device and the Phs-OCT probe is key. The invention adopts an oblique incidence integration mode (as shown in figure 1) in the structure, namely an included angle is formed between the jet emission probe and the long axis of the Phs-OCT scanning probe. In the signal control layer, Phs-OCT drives the working signal of the galvanometer as the trigger signal of the valve switch of the air injection device, so that the image acquisition and the air pulse emission are synchronous. In the scanning mode, an M-B scanning mode is adopted, wherein the M mode refers to that a certain specific position of the cornea is subjected to A-line scanning for multiple times to obtain the dynamic change process of the displacement along with the time; b-mode refers to two-dimensional tomographic imaging of the cornea. Therefore, the displacement change conditions of a plurality of positions of the cornea at a certain time can be obtained by adopting the M-B mode, so that the propagation condition of the elastic wave in the cornea tissue can be reflected.
(2) Phs-OCT is based on the interference spectrum signal that structure OCT gathered, converts phase information into through data processing to the high accuracy reflects deformation degree:
the balanced detector acquires interference spectrum intensity I (lambda), and the interference spectrum intensity I (lambda) is subjected to spectrum correction and DC item removal (the center frequency is changed from a carrier wave to zero), and is converted into an interference signal I (k) with wave number k as a variable. By fast discrete Fourier transform (FFT) to obtain complex-valued signals with depth z as variable, i.e.
And performing cross correlation on two adjacent A-lines to obtain phase information, wherein the phase information is as follows:
(3) constructing a cornea biomechanical model: corneal tissue is a viscoelastic tissue material, and the study uses the commonly used Kelvin-Voigt model to characterize the relationship between elasticity and viscosity of corneal tissue, i.e., parallel relationship.
According to the viscoelastic relationship in the Kelvin-Voigt model, the following formula can be obtained,
μ＝μ1+iωζ (4-3)
wherein μ is the coefficient of viscoelasticity, μ1For shear modulus, ω is the angle of the elastic waveFrequency, ζ is the shear viscosity. And the elastic modulus E and the shear modulus μ1The relationship of (a) is as follows,
E＝2(1+υ)μ1 (4-4)
propagation rate C (omega) and shear modulus mu of elastic wave1The angular frequency ω and the shear viscosity ζ are related as follows:
where ρ is the soft tissue density, when the soft tissue shear viscosity ζ is much less than the shear modulus μ1Then, the above formula can be simplified as:
and the energy attenuation coefficient alpha (omega) in the elastic wave propagation process satisfies the following formula:
(4) corneal viscoelasticity estimation: according to a cornea biomechanics mathematical model, under the condition that cornea tissue density rho and poisson ratio upsilon are constant, the premise of obtaining the elastic modulus E and the shear viscosity zeta is to clearly determine the elastic wave velocity C (omega), the central angular frequency omega of the elastic wave and the attenuation coefficient alpha (omega) of the elastic wave energy.
Assuming that the scan parameters of the OCE are set as follows, the M-mode value in the M-B mode is set as M, the B-mode value is set as n, and the time interval between adjacent A-lines is T, according to the Phs-OCT algorithm, the phase corresponding to the jth A-line at the ith bit point on the cornea is
Then take the maximum phase of the ith position
To characterize the propagation of elastic waves, then
Satisfies the following relation:
where the max function is taken to be the maximum and m is the number of A-lines scanned in total at the ith position, and will be
The corresponding j is defined as mji(z) the position of the ith position is xi. Since the corneal tissue cross-section is uniform over a local area, the elastic modulus E remains constant. The invention will mji(z) as abscissa, position xiAs ordinate, plotted as mji(z)-xiThe slope a is obtained by a least square method in a scattergram.
The elastic wave velocity C (ω) can be expressed as:
the energy Q of an elastic wave is proportional to the square of its amplitude, which is proportional to the phase, and thus the energy Q of an elastic wave is proportional to the square of the phase, i.e.
And elastic wave energy Q at the i-th siteiThe following relationship is satisfied:
wherein Q0Is the initial elastic wave energy, and is constant.
Thus, the present invention utilizes
To characterize elastic wave energy QiThen it is known
And xiThe attenuation coefficient α (ω) can be obtained by curve fitting.
And the central angular frequency omega can pass through the pair
Obtained by performing spectral analysis, i.e. on
Two-dimensional Fourier transform (FFT2) is performed to obtain spectrum information SPk,f，
Where k is the wave number and f is the frequency. Get SPk,fF corresponding to the maximum value is the center frequency fcThen can obtain
ω＝2πfc (4-13)
From the above, the elastic wave velocity C (ω), the central angular frequency ω of the elastic wave, and the elastic wave energy attenuation coefficient α (ω) are sequentially obtained, and the elastic modulus E and the shear viscosity ζ of the corneal tissue are estimated.
The invention fully utilizes the propagation characteristics of the elastic wave, estimates the elastic modulus of the soft tissue by utilizing the propagation speed of the elastic wave, and also comprehensively utilizes the energy attenuation coefficient and the central angle frequency of the elastic wave to extract the viscosity coefficient of the soft tissue.
The invention utilizes the attenuation characteristic of the elastic wave energy and extracts the attenuation coefficient of the elastic wave energy through curve fitting; meanwhile, two-dimensional Fourier transform is carried out on the phase information of different positions at different moments to obtain spatial frequency spectrum information, so that the central angle frequency of the elastic wave is extracted; the elastic wave energy attenuation coefficient and the central angular frequency are combined together to estimate the soft tissue viscosity coefficient.
The experimental device based on jet optical coherence elastography is shown in figure 1, a jet device is arranged between an OCT system and a sample, a jet nozzle of the jet device acts on corneal tissue of the sample, the jet nozzle and the corneal tissue of the sample are obliquely arranged, an included angle is formed between a jet emission nozzle and a long axis of a scanning probe of the OCT system, and the jet device of a jet device signal controller controls a trigger signal to synchronously control the scanning probe of the OCT system, so that image acquisition and air pulse emission are synchronous.
In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art. In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.
The skilled person should understand that: although the invention has been described in terms of the above specific embodiments, the inventive concept is not limited thereto and any modification applying the inventive concept is intended to be included within the scope of the patent claims.
The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.
Claims (2)
1. A method for non-invasively measuring the corneal viscoelasticity based on a jet optical coherence elastography technology is characterized by comprising the following steps:
(1) constructing and integrating a Phs-OCT system: integrating an air injection device and a Phs-OCT system to enable air pulses and Phs-OCT detection to simultaneously act on corneal tissues, and adopting an oblique incidence integration mode, namely forming an included angle between an air injection emission probe and a long axis of a Phs-OCT scanning probe, wherein at a signal control layer, Phs-OCT drives a galvanometer working signal to serve as a trigger signal of a valve switch of the air injection device to enable image acquisition and air pulse emission to be synchronously carried out;
(2) the doppler phase resolution algorithm applies: the method comprises the following steps of obtaining interference spectrum intensity I (lambda) by a balance detector, carrying out spectrum correction and direct current item removal, enabling the center frequency to be from a carrier wave to zero, converting the interference spectrum intensity I (lambda) into an interference signal I (k) with wave number k as a variable, and carrying out fast discrete Fourier transform (FFT) to obtain a complex value signal with depth z as a variable, namely an expression (1-1):
and performing cross correlation on two adjacent A-lines to obtain phase information, wherein the phase information is represented by the following formula (1-2):
(3) constructing a cornea biomechanical model: the common Kelvin-Voigt model is used to characterize the relationship between the elasticity and viscosity of corneal tissue, i.e. the two are in parallel relationship,
according to the viscoelastic relationship in the Kelvin-Voigt model, the following formulas (1-3) can be obtained,
μ＝μ1+iωζ (1-3)；
wherein μ is the coefficient of viscoelasticity, μ1For shear modulus, ω is the angular frequency of the elastic wave, and ζ is the shear viscosity; and the elastic modulus E and the shear modulus μ1The relationship of (A) is as follows (1-4),
E＝2(1+υ)μ1 (1-4)；
propagation rate C (omega) and shear modulus mu of elastic wave1The relationship between the angular frequency ω and the shear viscosity ζ is as follows (1 to 5):
where ρ is the soft tissue density, when the soft tissue shear viscosity ζ is much less than the shear modulus μ1Then, the above formula can be simplified to formula (1-6),
and the energy attenuation coefficient alpha (omega) in the elastic wave propagation process satisfies the following formula (1-7):
(4) corneal viscoelasticity estimation: according to a cornea biomechanics mathematical model, under the condition that the cornea tissue density rho and the Poisson ratio upsilon are certain, the premise of obtaining the elastic modulus E and the shear viscosity zeta is to clearly determine the elastic wave speed C (omega) and the central angular frequency omega of the elastic wave0And the elastic wave energy attenuation coefficient α (ω);
assume that the scan parameters of the OCE are set as followsSetting the M mode value as M, the B mode value as n and the time interval between adjacent A-lines as T in the M-B mode, and setting the phase corresponding to the jth A-line of the ith bit point on the cornea as T according to the Phs-OCT algorithm
Then take the maximum phase of the ith position
To characterize the propagation of elastic waves, then
Satisfies the following relational expression (1-8):
where the max function is taken to be the maximum and m is the number of A-lines scanned in total at the ith position, and will be
The corresponding j is defined as mji(z) the position of the ith position is xiSince the corneal tissue cross section is uniform over a local area, the elastic modulus E remains unchanged; will mji(z) as abscissa, position xiAs ordinate, plotted as mji(z)-xiA scatter diagram, and the slope a can be obtained by using a least square method;
the elastic wave velocity C (ω) can be represented by the formula (1-9):
the energy Q of the elastic wave is proportional to the square of its amplitude, which is proportional to the phase, and therefore the energy Q of the elastic wave is proportional to the square of the phase, i.e. the equations (1-10),
and elastic wave energy Q at the i-th siteiSatisfies the following relational expression (1-11):
wherein Q0Is the initial elastic wave energy, is a constant;
by using
To characterize elastic wave energy QiThen it is known
And xiObtaining the attenuation coefficient alpha (omega) through curve fitting;
and a central angular frequency omega0Can pass through the pair
Obtained by performing spectral analysis, i.e. on
Two-dimensional Fourier transform (FFT2) is performed to obtain spectrum information SPk,fAs shown in formulas (1-12),
where k is the wave number and f is the frequency, then SP is takenk,fF corresponding to the maximum value is the center frequency fcThen, the formula (1-13) can be obtained,
ω0＝2πfc (1-13)；
from the above, the elastic wave velocity C (ω) and the central angular frequency of the elastic wave can be obtained in turnRate omega0And the elastic wave energy attenuation coefficient alpha (omega), thereby estimating the elastic modulus E and the shear viscosity zeta of the corneal tissue.
2. The method for non-invasively measuring the corneal viscoelasticity based on the jet optical coherence elastography technology as claimed in claim 1, wherein the Phs-OCT system employs an M-B scanning mode, wherein the M mode refers to a plurality of a-line scans of the cornea for a specific position of the cornea to obtain a dynamic variation process of displacement with time; the B mode refers to two-dimensional tomography of the cornea, and the displacement change conditions of a plurality of positions of the cornea at a certain time can be obtained by adopting the M-B mode, so that the propagation condition of elastic waves in the cornea tissue is reflected.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910034893.4A CN109875504B (en) | 2019-01-15 | 2019-01-15 | Method for non-invasively measuring corneal viscoelasticity based on jet optical coherence elastography technology |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910034893.4A CN109875504B (en) | 2019-01-15 | 2019-01-15 | Method for non-invasively measuring corneal viscoelasticity based on jet optical coherence elastography technology |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109875504A CN109875504A (en) | 2019-06-14 |
| CN109875504B true CN109875504B (en) | 2021-07-30 |
Family
ID=66926085
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910034893.4A Active CN109875504B (en) | 2019-01-15 | 2019-01-15 | Method for non-invasively measuring corneal viscoelasticity based on jet optical coherence elastography technology |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109875504B (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110287617B (en) * | 2019-06-28 | 2022-09-27 | 中北大学 | Design of high-power ultrasonic transducer and related parameter solving method |
| CN110426372B (en) * | 2019-07-16 | 2021-10-22 | 南昌航空大学 | Elastic modulus imaging detection method for frequency-sweeping Brillouin scatterer |
| CN110426373B (en) * | 2019-07-16 | 2021-11-26 | 南昌航空大学 | In-situ detection method for Brillouin scattering and optical coherence elastography |
| CN110772217A (en) * | 2019-10-18 | 2020-02-11 | 南昌航空大学 | Method for improving signal-to-noise ratio of Brillouin elastography system through interference type optical path |
| CN110974148B (en) * | 2019-12-03 | 2022-01-07 | 温州医科大学 | Method for measuring cornea elastic modulus of in-vivo human eye based on jet optical coherence elastography technology |
| CN111449629B (en) * | 2020-04-28 | 2023-04-25 | 北京信息科技大学 | Optical coherence elastography method and device |
| CN111671390A (en) * | 2020-05-25 | 2020-09-18 | 广东唯仁医疗科技有限公司 | Method for extracting pulse parameters of trabecular network |
| CN113367653A (en) * | 2021-05-13 | 2021-09-10 | 佛山科学技术学院 | Method, system and storage medium for non-contact measurement of corneal viscoelasticity |
| CN113413139B (en) * | 2021-06-22 | 2022-09-16 | 赵雁之 | Image fusion device based on optical coherent elastography |
| CN113712503B (en) * | 2021-09-06 | 2023-06-09 | 温州医科大学 | OCT probe applied to fundus operation |
| CN115682988B (en) * | 2022-12-13 | 2023-05-09 | 浙江大学 | QME detection system for human tissue edge |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103006274A (en) * | 2012-12-21 | 2013-04-03 | 深圳大学 | Method and system for ultrasonic detection of cornea viscoelasticity |
| CN104367347A (en) * | 2014-05-16 | 2015-02-25 | 深圳大学 | System and method for measuring intra-ocular pressure and cornea viscoelasticity |
| CN104434028A (en) * | 2014-11-15 | 2015-03-25 | 中国科学院光电技术研究所 | System and method for combining cornea elasticity imaging with anterior segment structure imaging |
| CN109171639A (en) * | 2018-09-04 | 2019-01-11 | 温州医科大学 | A kind of measuring device and measuring method in body corneal parameters based on Optical Coherence Tomography Imaging Technology |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI507170B (en) * | 2012-10-24 | 2015-11-11 | Crystalvue Medical Corp | Optical apparatus and operating method thereof |
| TW201501688A (en) * | 2013-07-09 | 2015-01-16 | Univ Nat Taiwan | Non-contact system for measuring corneal properties and method for measuring corneal elastic constant and viscosity constant |
| US9687145B2 (en) * | 2014-11-10 | 2017-06-27 | University Of Houston System | Optical coherence elastography to assess biomechanics and detect progression of ocular and other tissues degenerative diseases |
-
2019
- 2019-01-15 CN CN201910034893.4A patent/CN109875504B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103006274A (en) * | 2012-12-21 | 2013-04-03 | 深圳大学 | Method and system for ultrasonic detection of cornea viscoelasticity |
| CN104367347A (en) * | 2014-05-16 | 2015-02-25 | 深圳大学 | System and method for measuring intra-ocular pressure and cornea viscoelasticity |
| CN104434028A (en) * | 2014-11-15 | 2015-03-25 | 中国科学院光电技术研究所 | System and method for combining cornea elasticity imaging with anterior segment structure imaging |
| CN109171639A (en) * | 2018-09-04 | 2019-01-11 | 温州医科大学 | A kind of measuring device and measuring method in body corneal parameters based on Optical Coherence Tomography Imaging Technology |
Non-Patent Citations (4)
| Title |
|---|
| Assessing corneal viscoelasticity after crosslinking at different IOP by noncontact OCE and a modified Lamb wave model;Zhaolong Han,et al;《Proc. of SPIE》;20171231;第10045卷;第1-5页 * |
| Assessing the viscoelasticity of green light induced CXL in the rabbit cornea by noncontact OCE and FEM;Zhaolong Han，et al;《SPIE BiOS》;20161231;第1-5页 * |
| Dynamic Optical Coherence Elastography of Soft Tissue;Kirill V. Larin;《IEEE》;20180813;第509页 * |
| Quantitative Assessment of Thin-Layer Tissue Viscoelastic Properties Using Ultrasonic Micro-Elastography With Lamb Wave Model;Cho-Chiang Shih，et al;《IEEE TRANSACTIONS ON MEDICAL IMAGING》;20180831;第37卷(第8期);第1887-1898页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109875504A (en) | 2019-06-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109875504B (en) | Method for non-invasively measuring corneal viscoelasticity based on jet optical coherence elastography technology | |
| Ambroziński et al. | Acoustic micro-tapping for non-contact 4D imaging of tissue elasticity | |
| US11413007B2 (en) | Non-contact acoustic radiation force based (ARF-based) generation of broad bandwidth mechanical waves using air-coupled ultrasound | |
| US20220110523A1 (en) | Arrangement for eye pressure measurements | |
| JP4451309B2 (en) | Apparatus and method for measuring elasticity of human or animal organs | |
| Strohm et al. | Quantitative measurements of apoptotic cell properties using acoustic microscopy | |
| Gennisson et al. | Assessment of elastic parameters of human skin using dynamic elastography | |
| US5810731A (en) | Method and apparatus for elasticity imaging using remotely induced shear wave | |
| CN110974148B (en) | Method for measuring cornea elastic modulus of in-vivo human eye based on jet optical coherence elastography technology | |
| US9364194B2 (en) | Systems and methods for detecting regions of altered stiffness | |
| JP3875581B2 (en) | Ultrasound diagnostic system | |
| Lawrence | Physics and instrumentation of ultrasound | |
| US20090116032A1 (en) | Optical Coherence Tomography / Acoustic Radiation Force Imaging Probe | |
| CN108445077B (en) | Optical elasticity test method | |
| CN103006274A (en) | Method and system for ultrasonic detection of cornea viscoelasticity | |
| CN109745077A (en) | Based on the elastic characteristic detection method for focusing ultrasonic sound and vibration signal | |
| CN112022215A (en) | Ultrasonic elastography cornea detection method, device and system and storage medium | |
| CN111449629B (en) | Optical coherence elastography method and device | |
| Vannacci et al. | Wide bandwidth fiber-optic ultrasound probe in MOMS technology: Preliminary signal processing results | |
| Zhang et al. | Measurement of quantitative viscoelasticity of bovine corneas based on lamb wave dispersion properties | |
| Detrez et al. | Flow Controlled Air Puff Generator Towards In Situ Brain Tumor Detection Based on MHz Optical Coherence Elastography | |
| CN111436910A (en) | Optical coherence tomography multi-modal imaging device and method for living tissue | |
| CN109875608B (en) | Elastography method | |
| CN109009229A (en) | A kind of device and method of sclera mechanical characteristic in body quantitative measurment | |
| Sarvazyan et al. | Potential biomedical applications of non-dissipative acoustic radiation force |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |