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Quantifying human crystalline lens geometry as a function of age and accommodation is important for improved cataract and presbyopia treatments. In previous works we presented eigenlenses as a basis of 3-D functions to represent the full shape of the crystalline lens ex vivo. Also, we presented the application of eigenlenses to estimate the full shape of the lens in vivo from 3-D optical coherence tomography (OCT) images, where only the central part of the lens -visible through the pupil- is available. The current work presents a validation of the use of eigenlenses to estimate in vivo the full shape of dis-accommodated lenses. We used 14 ex vivo crystalline lenses from donor eyes (11-54 y/o) mounted in a lens stretcher, and measured the geometry and the power of the lenses using a combined OCT and ray tracing aberrometry system. Ex vivo, the full extent of the lens is accessible from OCT because the incident light is not blocked by the iris. We measured in non-stretched (fully accommodated) and stretched (mimicking in vivo dis-accommodated lenses) conditions. Then, we simulated computationally in vivo conditions on the obtained ex vivo lenses geometry (assuming that just the portion of the lens within a given pupil is available), and estimated the full shape using eigenlenses. The mean absolute error (MAE) between estimated and measured lens’ diameters and volumes were MAE=0.26 ± 0.18 mm and MAE=7.0 ± 4.5 mm³, respectively. Furthermore, we concluded that the estimation error between measured and estimated lenses did not depend on the accommodative state (change in power due to stretching), and thus eigenlenses are also useful for the full shape estimation of in vivo dis-accommodated lenses.

The localized application of the riboflavin/UV-A collagen cross-linking (UV-CXL) corneal treatment has been proposed to concentrate the stiffening process only in the compromised regions of the cornea by limiting the epithelium removal and irradiation area. However, current clinical screening devices dedicated to measuring corneal biomechanics cannot provide maps nor spatial-dependent changes of elasticity in corneas when treated locally with UV-CXL. In this study, we leverage our previously reported confocal air-coupled ultrasonic optical coherence elastography (ACUS-OCE) probe to study local changes of corneal elasticity in three cases: untreated, half-CXL-treated, and full-CXL-treated in vivo rabbit corneas (n = 8). We found a significant increase of the shear modulus in the half-treated (>450%) and full-treated (>650%) corneal regions when compared to the non-treated cases. Therefore, the ACUS-OCE technology possesses a great potential in detecting spatially-dependent mechanical properties of the cornea at multiple meridians and generating elastography maps that are clinically relevant for patient-specific treatment planning and monitoring of UV-CXL procedures.

Transient optical coherence elastography (OCE) has undergone rapid development over the past couple of decades with introductions of new techniques for inducing motion in tissues, developments of robust signal processing algorithms, and demonstrations of transient OCE methods in humans in vivo. Transient OCE is widely used due to its simplicity, adoption of established techniques from other fields, and ability to quantify tissue biomechanical properties with no knowledge of the excitation force. The past few years have seen a transition from rapid development and demonstrations of novel techniques to rigorous studies analyzing the technical capabilities and limitations of transient OCE methods and live human studies. In this chapter, we describe how to link OCE-measured motion to tissue biomechanical properties, discuss practical system design aspects, and showcase recent applications of transient OCE, focused on wave-based OCE. Finally, we consider the prospects of transient OCE and the next steps that are required to fully establish transient OCE as a viable clinical imaging modality.

Collagen XII plays a role in regulating the structure and mechanical properties of the cornea. In this work, several optical elastography techniques were used to investigate the effect of collagen XII deficiency on the stiffness of the murine cornea.A three-prong optical elastography approach was used to investigate the mechanical properties of the cornea. Brillouin microscopy, air-coupled ultrasonic optical coherence elastography (OCE) and heartbeat OCE were used to assess the mechanical properties of wild type (WT) and collagen XII-deficient (Col12a1-/-) murine corneas. The Brillouin frequency shift, elastic wave speed, and compressive strain were all measured as a function of intraocular pressure (IOP).All three optical elastography modalities measured a significantly decreased stiffness in the Col12a1-/- compared to the WT (P0.01 for all three modalities). The optical coherence elastography techniques showed that mean stiffness increased as a function of IOP; however, Brillouin microscopy showed no discernable trend in Brillouin frequency shift as a function of IOP.Our approach suggests that the absence of collagen XII significantly softens the cornea. Although both optical coherence elastography techniques showed an expected increase in corneal stiffness as a function of IOP, Brillouin microscopy did not show such a relationship, suggesting that the Brillouin longitudinal modulus may not be affected by changes in IOP. Future work will focus on multimodal biomechanical models, evaluating the effects of other collagen types on corneal stiffness, and in vivo measurements.

We derive closed-form solutions for reverberant elastography in anisotropic elastic media by adapting the framework used in electromagnetic theory to treat transverse isotropic materials. Different sample-setup geometries are analyzed, highlighting their relevance for both optical coherence elastography (OCE) and ultrasound elastography (USE). Numerical simulations using finite elements are used to validate the proposed solutions in practical cases. OCE experiments are conducted in ex vivo chicken muscle samples for the characterization of in-plane and out-of-plane shear modulus assuming a transverse isotropic elastic model. Additionally, we obtained a generalized geometry-independent solution for the isotropic media case, thus unifying previous results for reverberant elastography., Comment: 12 pages, 14 figures

In this study, we propose to measure the spatial deformation spreading (SDS) produced by an air-pulse on the surface of tissues during the near-field regime of propagation as a metric to characterize degree of anisotropy. Experiments in isotropic tissue-mimicking phantoms and anisotropic chicken tibialis muscle were conducted using an optical coherence tomography system synchronized with a confocal air-pulse stimulation. SDS ratio measured along versus across the direction of fibers in chicken muscle agreed with the wave speed ratio taken at the same directions, demonstrating the capabilities of the air-pulse SDS technique in measuring the elastic anisotropy of transverse isotropic tissues.

We have designed and developed an air-coupled ultrasonic radiation force probe co-focused with a phase-sensitive optical coherence tomography system (ACUS-OCT). Our custom-made 1 MHz spherically focused piezo-electric transducer with a concentric circular opening of 10 mm diameter allows for the confocal micro-excitation of waves and the spatial (2D, 3D) motion measurement of tissues. Phantom studies demonstrated the capabilities of this probe to produce quasi-harmonic excitation up to 4 kHz for the generation of highly localized elastic waves. Experimental results in ocular tissues showed the highly localized 2D/3D elasticity mapping capabilities of this approach with great potential for clinical translation.

The purpose of this study is to evaluate the changes in elasticity of the corneo-scleral limbus when the eye-globe is subjected to different intraocular pressures. Continuous elastic waves were mechanically induced in the sclera and imaged using a phase-sensitive optical coherence tomography system. Experimental results showed a marked heterogeneity of wave speed across the corneal-limbal-scleral region, which increased as a function of IOP. The conclusion of this study reveals that the corneo-scleral limbus tissue is more mechanically nonlinear compared to the cornea and sclera. This suggests that limbus acts as a supporting and accommodating mechanical structure for the cornea.

In optical coherence elastography (OCE), air-pulse stimulation has been widely used to produce propagation of mechanical waves for elastic characterization of tissues. In this paper, we propose the use of spatial deformation spreading (SDS) on the surface of samples produced by air-pulse stimulation for the OCE of transverse isotropic tissues. Experiments in isotropic tissue-mimicking phantoms and anisotropic chicken tibialis muscle were conducted using a spectral-domain optical coherence tomography system synchronized with a confocal air-pulse stimulation. SDS measurements were compared with wave speeds values calculated at different propagation angles. We found an approximately linear relationship between shear wave speed and SDS in isotropic phantoms, which was confirmed with predictions made by the numerical integration of a wave propagation model. Experimental measurements in chicken muscle show a good agreement between SDS and surface wave speed taken along and across the axis of symmetry of the tissues, also called degree of anisotropy. In summary, these results demonstrated the capabilities of SDS produced by the air-pulse technique in measuring the shear elastic anisotropy of transverse isotropic tissues.

Purpose Currently, the biomechanical properties of the corneo-scleral limbus when the eye-globe deforms are largely unknown. The purpose of this study is to evaluate changes in elasticity of the cornea, sclera, and limbus when subjected to different intraocular pressures (IOP) using wave-based optical coherence elastography (OCE). Special attention was given to the elasticity changes of the limbal region with respect to the elasticity variations in the neighboring corneal and scleral regions. Methods Continuous harmonic elastic waves (800 Hz) were mechanically induced in the sclera near the corneo-sclera limbus of in situ porcine eye-globes (n = 8). Wave propagation was imaged using a phase-sensitive optical coherence tomography system (PhS-OCT). The eyes were subjected to five different IOP-levels (10, 15, 20, 30, and 40 mm Hg), and spatially distributed propagation velocities were calculated along corneal, limbal, and scleral regions. Finite element analysis (FEA) of the same regions under the same excitation conditions were conducted for further validation of results. Results FEA demonstrated that the stiffness of the heterogeneous cornea-limbus-sclera transition can be characterized by phase velocity measurements of the elastic waves produced at 800 Hz in the anterior eye. Experimental results revealed that the wave speed in the limbus (cL = 6.5 m/s) is between the cornea (cc = 2.9 m/s) and sclera (cs = 10.0 m/s) at a physiological IOP level (15 mm Hg) and rapidly increases as the IOP level is increased, even surpassing the wave speed in the sclera. Finally, the change in elastic wave speed in the limbus (ΔcL∼18.5 m/s) was greater than in the cornea (Δcc ∼12.6 m/s) and sclera (Δcs∼8.1 m/s) for the same change in IOP. Conclusions We demonstrated that wave-based OCE can be utilized to assess limbus biomechanical properties. Moreover, experimental evidence showed that the corneo-scleral limbus is highly nonlinear compared to the cornea and sclera when the eye-globe is deformed by an increase of IOP. This may suggest that the limbus has enough structural flexibility to stabilize anterior eye shape during IOP changes.

In this work, we study the conditions in which a reverberant field is created by varying the number and locations of multiple mechanical sources, and then fitting axial and lateral autocorrelation profiles to theoretical models. Numerical simulation showed that at least 60 incident plane waves were necessary to generate a R-SWF. The general trend is that by applying more incident waves, the coefficient of determination improves and the error decreases. We report a bias error lower than 6% in the mean shear wave speed $(\pmb{C}_{s})$ . Phantom experiments showed a similar tendency. Moreover, we demonstrated that the creation of a R-SWF based on the superposition of incident plane waves was possible. At least three vibration sources located at the top of the phantom surface were necessary to measure an average $\pmb{C}_{s}$ with an error less than 9%.

Excitation of dye-loaded perfluorocarbon nanoparticles (nanobombs) can generate highly localized axially propagating longitudinal shear waves (LSW) that can be used to quantify tissue mechanical properties without transversal scanning of the imaging beam. In this study, we used repetitive excitations of dodecafluoropentane (C5) and tetradecafluorohexane (C6) nanobombs by a nanosecond-pulsed laser to produce multiple LSWs from a single spot in a phantom. A 1.5 MHz Fourier-domain mode-locked laser in combination with a phase correction algorithm was used to perform elastography. Multiple nanobomb activations were also monitored by detecting photoacoustic signals. Our results demonstrate that C6 nanobombs can be used for repetitive generation of LSW from a single spot for the purpose of material elasticity assessment. This study opens new avenues for continuous quantification of tissue mechanical properties using single delivery of the nanoparticles.

Longitudinal shear waves (LSW) are waves with longitudinally polarized displacement that travel at the shear wave speed through depth when generated at the surface of tissues. In this study, we explore LSW generated by a circular glass plate in contact with the sample. Results demonstrated the potential of LSW in detecting an elasticity gradient along axial (resolution < 0.13 mm) and lateral (resolution < 0.78 mm) directions simultaneously. Finally, LSWs are used for the elastography of ex vivo mouse brain and demonstrated differentiated LSW speed values between the cerebral cortex (2.91 m/s) and cerebellum/midbrain (1.18 m/s) regions.

Optical coherence elastography (OCE) has seen rapid growth since its introduction in 1998. The past few decades have seen tremendous advancements in the development of OCE technology and a wide range of applications, including the first clinical applications. This tutorial introduces the basics of solid mechanics, which form the foundation of all elastography methods. We then describe how OCE measurements of tissue motion can be used to quantify tissue biomechanical parameters. We also detail various types of excitation methods, imaging systems, acquisition schemes, and data processing algorithms and how various parameters associated with each step of OCE imaging can affect the final quantitation of biomechanical properties. Finally, we discuss the future of OCE, its potential, and the next steps required for OCE to become an established medical imaging technology.

43 pags., 18 figs., After ten years of progress and innovation, optical coherence elastography (OCE) based on the propagation of mechanical waves has become one of the major and the most studied OCE branches, producing a fundamental impact in the quantitative and nondestructive biomechanical characterization of tissues. Preceding previous progress made in ultrasound and magnetic resonance elastography; wave-based OCE has pushed to the limit the advance of three major pillars: (a) implementation of novel wave excitation methods in tissues, (b) understanding new types of mechanical waves in complex boundary conditions by proposing advance analytical and numerical models, and (c) the development of novel estimators capable of retrieving quantitative 2D/3D biomechanical information of tissues. This remarkable progress promoted a major advance in answering basic science questions and the improvement of medical disease diagnosis and treatment monitoring in several types of tissues leading, ultimately, to the first attempts of clinical trials and translational research aiming to have wave-based OCE working in clinical environments. This paper summarizes the fundamental up-to-date principles and categories of wave-based OCE, revises the timeline and the state-of-the-art techniques and applications lying in those categories, and concludes with a discussion on the current challenges and future directions, including clinical translation research., The authors would like to acknowledge the research support provided by NIH grants R01EY022362, R01EY030063, R61AR078078, and R01HD095520.

Cutaneous Leishmaniasis is a skin infection which is commonly present in underdeveloped countries. The incidence is particularly high in amazonic countries of Latin-America like Brazil, Colombia and Perú and is usually reported as endemic. In Perú, more than one million people are at risk of infection and approximately 6,000 new cases are detected each year. The present work proposes to integrate a set of control, monitoring and disease quantification procedures in: (1) an automated tool to expedite the analysis in laboratories studying parasiticidal agents and (2) a non-invasive treatment monitoring protocol. The first, consists in the adaptation of an optical microscope KRUSS MBL3100 to perform a fast image capture and automated promastigotes identification. This may be of value to evaluate the effectiveness of various parasiticidal agents. The counting process is performed by an automatic segmentation in the RGB green color space discriminating elements by their area. The second, proposes a protocol for monitoring the evolution of the disease treatment divided into three stages: supra-skin modeling and reconstruction, subcutaneous exploration by textural characteristics and volumetric segmentation. This protocol is performed using a Next Engine HD 3D scanner and a Vevo Visualsonix 2100 ultrasonic scanner. The results show improvements in sample processing time, accuracy and inter- and intra-operational variability. The sensitivity and accuracy of the microscopic identification system was of 97% and 92% respectively. The exactitude and precision error was up to 2% and the sensitivity and specificity went as high as 71% in the 3D reconstruction and texture analysis respectively.

The determination of shear wave speed is an important subject in the field of elastography, since elevated shear wave speeds can be directly linked to increased stiffness of tissues. MRI and ultrasound scanners are frequently used to detect shear waves and a variety of estimators are applied to calculate the underlying shear wave speed. The estimators can be relatively simple if plane wave behavior is assumed with a known direction of propagation. However, multiple reflections from organ boundaries and internal inhomogeneities and mode conversions can create a complicated field in time and space. Thus, we explore the mathematics of multiple component shear wave fields and derive the basic properties, from which efficient estimators can be obtained. We approach this problem from the historic perspective of reverberant fields, a conceptual framework used in architectural acoustics and related fields. The framework can be recast for the alternative case of shear waves in a bounded elastic media, and the expected value of displacement patterns in shear reverberant fields are derived, along with some practical estimators of shear wave speed. These are applied to finite element models and phantoms to illustrate the characteristics of reverberant fields and provide preliminary confirmation of the overall framework.

In medicine, both pathological (e.g. cirrhosis) and non-pathological states (e.g. aging) can be characterized by changes in the mechanical properties of biological tissue. The use of optical techniques to measure and map the elastic properties of soft tissue, known as optical elastography, is an emergent field with applications in various clinical disciplines, including ophthalmology and dermatology. In this paper, a brief overview of optical elastography will be provided with a short taxonomy. Categories include appropriate types of tissue models (semi-infinite, single thin layer, composite stacks), clinical tasks (classification or estimation), and excitation modes (transient, continuous, quasi-static, or molecular shift). We will then discuss examples of current advances, including optical coherence elastography using reverberant shear wave fields and Brillouin microscopy. The examples will demonstrate how current and future techniques may address clinical needs. Advantages and disadvantages of these techniques will be presented, augmenting the framework of the categorization system. With emerging applications, the taxonomy may be expanded providing a roadmap to future techniques.

We present an air-coupled ultrasonic radiation force probe co-focused with a phase-sensitive optical coherence tomography (OCT) system for quantitative wave-based elastography. A custom-made 1 MHz spherically focused piezoelectric transducer with a concentric 10 mm wide circular opening allowed for confocal micro-excitation of waves and phase-sensitive OCT imaging. Phantom studies demonstrated the capabilities of this probe to produce quasi-harmonic excitation up to 4 kHz for generation of elastic waves. Experimental results in ocular tissues showed highly detailed 2D and 3D elasticity mapping using this approach with great potential for clinical translation.

Determining the mechanical properties of tissue such as elasticity and viscosity is fundamental for better understanding and assessment of pathological and physiological processes. Dynamic optical coherence elastography uses shear/surface wave propagation to estimate frequency-dependent wave speed and Young’s modulus. However, for dispersive tissues, the displacement pulse is highly damped and distorted during propagation, diminishing the effectiveness of peak tracking approaches. The majority of methods used to determine mechanical properties assume a rheological model of tissue for the calculation of viscoelastic parameters. Further, plane wave propagation is sometimes assumed which contributes to estimation errors. To overcome these limitations, we invert a general wave propagation model which incorporates (1) the initial force shape of the excitation pulse in the space-time field, (2) wave speed dispersion, (3) wave attenuation caused by the material properties of the sample, (4) wave spreading caused by the outward cylindrical propagation of the wavefronts, and (5) the rheological-independent estimation of the dispersive medium. Experiments were conducted in elastic and viscous tissue-mimicking phantoms by producing a Gaussian push using acoustic radiation force excitation, and measuring the wave propagation using a swept-source frequency domain optical coherence tomography system. Results confirm the effectiveness of the inversion method in estimating viscoelasticity in both the viscous and elastic phantoms when compared to mechanical measurements. Finally, the viscoelastic characterization of collagen hydrogels was conducted. Preliminary results indicate a relationship between collagen concentration and viscoelastic parameters which is important for tissue engineering applications.

Finite element analysis (FEA) is used to analyze the static and dynamic structural behavior providing important information for the conservation of monuments in cultural heritage. Accurate solid models are fundamental in this type of analysis, but the structural changes introduced during the lifetime of the monument produce complex geometrical configurations that may not be generated with the desired accuracy in standard CAD solid modeling software. On the other hand, techniques such as laser scanning or photogrammetry can reproduce accurate geometrical information but only of the surface of the monument which cannot be directly applied for FEA. We introduce a novel methodology for locally updating an existing 3D solid model of a complex monumental structure with the geometric information provided by a 3D mesh extracted from the digital survey of a specific sector of the monument. The methodology starts by registering the new information from the digital survey to the existing solid model of the monument. The difference between the models is used to highlight the region of interest (ROI) to be updated. The ROI is encapsulated and transformed into a solid space where Boolean operations are used to update the original solid model. We test the procedure on Huaca de la Luna, Trujillo, Peru, one of the most important massive earthen structures of the Moche civilization. Solid models are defined in AutoCAD while 3D meshes are recorded with a Faro Focus laser scanner. The results indicate that the proposed methodology is effective at transferring complex geometrical and topological features from the mesh to the solid modeling space.

Skin lesions change elastic properties near the surface. In the last decades, several non-invasive elastography techniques have been developed for detecting the mechanical properties of tissue. In particular, harmonic elastography is characterized for inducing shear wave propagation by an external vibrator in order to estimate shear modulus. However, near the boundary region, propagation is governed by surface acoustic waves (SAW). This paper combines crawling waves elastography with a high-frequency ultrasound (HFUS) system for the estimation of the SAW-to-shear compensation factor when ultrasound (US) gel is used as coupling interface. Experiments explore the SAWspeed in a homogeneous phantom with a solid-water interface in order to corroborate theoretical findings. Subsequently, experiments in a solid-US gel interface are conducted in order to find the correct compensation factor. Preliminary results suggest that SAW propagation can be detected using HFUS, and shear velocity maps can be generated by applying the estimated empirical correction factor. This study will potentially avoid the underestimation of shear modulus when using SAW-based HFUS elastography which is promising for the better diagnosis of skin diseases.

Several tropical diseases generate cutaneous lesions on the skin with different elastic properties than normal tissue. A number of non-invasive elastography techniques have been created for detecting the mechanical properties in tissue in the last decades. Quantitative information is mainly obtained by harmonic elastography, which is distinguished for producing shear wave propagation. When wave propagation is near a boundary region, surface acoustic waves (SAW) are found. This work presents crawling waves elastography technique implemented with a high-frequency ultrasound (HFUS) system for the estimation of SAW speed and its relationship with the elastic modulus. Experiments are conducted to measure SAW speed in a homogeneous phantom with a solid-water interface for a theoretical validation. Afterwards, ex-vivo experiments in thigh pork were performed to show SAW propagation in animal tissue. Preliminary results demonstrate the presence of SAW propagation in phantoms and skin tissue and how wave speed should be correctly adjusted according to the coupling media for elastography applications.

In dynamic optical coherence elastography (OCE), surface acoustic waves are the predominant perturbations. They constrain the quantification of elastic modulus to the direction of wave propagation only along the surface of tissues, and disregard elasticity gradients along depth. Longitudinal shear waves (LSW), on the other hand, can be generated at the surface of the tissue and propagate through depth with desirable properties for OCE: (1) LSW travel at the shear wave speed and can discriminate elasticity gradients along depth, and (2) the displacement of LSW is longitudinally polarized along the direction of propagation; therefore, it can be measured by a phase-sensitive optical coherence tomography system. In this study, we explore the capabilities of LSW generated by a circular glass plate in contact with a sample using numerical simulations and tissue-mimicking phantom experiments. Results demonstrate the potential of LSW in detecting an elasticity gradient along axial and lateral directions simultaneously. Finally, LSW are used for the elastography of ex vivo mouse brain and demonstrate important implications in in vivo and in situ measurements of local elasticity changes in brain and how they might correlate with the onset and progression of degenerative brain diseases.

Elastography is a technique that measures and maps the local elastic property of biological tissues. Aiming for detection of micron-scale inclusions, various optical elastography, especially optical coherence elastography (OCE), techniques have been investigated over the past decade. The challenges of current optical elastography methods include the decrease in elastographic resolution as compared with its parent imaging resolution, the detection sensitivity and accuracy, and the cost of the overall system. Here we report for the first time, we believe, on an elastography technique—crawling wave optical coherence elastography (CRW-OCE)—which significantly lowers the requirements on the imaging speed and opens the path to high-resolution and high-sensitivity OCE at relatively low cost. Methods of crawling wave excitation, data acquisition, and crawling wave tracking are presented.

Optical Coherence Elastography (OCE) is a widely investigated noninvasive technique for estimating the mechanical properties of tissue. In particular, vibrational OCE methods aim to estimate the shear wave velocity generated by an external stimulus in order to calculate the elastic modulus of tissue. In this study, we compare the performance of five acquisition and processing techniques for estimating the shear wave speed in simulations and experiments using tissue-mimicking phantoms. Accuracy, contrast-to-noise ratio, and resolution are measured for all cases. The first two techniques make the use of one piezoelectric actuator for generating a continuous shear wave propagation (SWP) and a tone-burst propagation (TBP) of 400 Hz over the gelatin phantom. The other techniques make use of one additional actuator located on the opposite side of the region of interest in order to create an interference pattern. When both actuators have the same frequency, a standing wave (SW) pattern is generated. Otherwise, when there is a frequency difference df between both actuators, a crawling wave (CrW) pattern is generated and propagates with less speed than a shear wave, which makes it suitable for being detected by the 2D cross-sectional OCE imaging. If df is not small compared to the operational frequency, the CrW travels faster and a sampled version of it (SCrW) is acquired by the system. Preliminary results suggest that TBP (error < 4.1%) and SWP (error < 6%) techniques are more accurate when compared to mechanical measurement test results.

Various types of waves are produced when a harmonic force is applied to a semi-infinite half space elastic medium. In particular, surface waves are perturbations with transverse and longitudinal components of displacement that propagate in the boundary region at the surface of the elastic solid. Shear wave speed estimation is the standard for characterizing elastic properties of tissue in elastography; however, the penetration depth of Optical Coherence Tomography (OCT) is typically measured in millimeters constraining the measurement region of interest to be near the surface. Plane harmonic Rayleigh waves propagate in solid-vacuum interfaces while Scholte waves exist in solid-fluid interfaces. Theoretically, for an elastic solid with a Poisson’s ratio close to 0.5, the ratio of the Rayleigh to shear wave speed is 95%, and 84% for the Scholte to shear wave. Our study demonstrates the evidence of Rayleigh waves propagating in the solid-air boundary of tissue-mimicking elastic phantoms. Sinusoidal tone-bursts of 400Hz and 1000 Hz were excited over the phantom by using a piezoelectric actuator. The wave propagation was detected with a phase-sensitive OCT system, and its speed was measured by tracking the most prominent peak of the tone in time and space. Similarly, this same experiment was repeated with a water interface. In order to obtain the shear wave speed in the material, mechanical compression tests were conducted in samples of the same phantom. A 93.9% Rayleigh-shear and 82.4% Scholte-Shear speed ratio were measured during experiments which are in agreement with theoretical results.