Nondestructive measurement of anterior cerebral artery stiffness using optical coherence elastography.

Through-thickness strain field characterization and internal defect detection in polymer films using optical coherence elastography

Seborrheic keratosis is a common benign skin tumor. None of the current conventional testing techniques can assess the mechanical properties of the tissue, such as hardness, elasticity and viscoelasticity. In this study, we investigated the morphological and elastic properties of seborrheic keratosis (SK), a common benign skin tumor, using optical coherence elastography (OCE). We found that the OCE technique was able to distinguish SK tissue from normal tissue. In addition, by measuring skin elasticity, it was possible to identify SK lesions with different clinical types and dermoscopic patterns of presentation. As a non-invasive quantitative tool, OCE demonstrates significant potential in the clinical diagnosis and assessment of skin aging diseases, providing objective evaluations based on elasticity.

Abstract Optical elastography is rapidly evolving for assessing tissue biomechanical properties, and these techniques are now reaching technical maturity, resulting in large-scale clinical studies. However, a lack of extensive research on intra- and inter-operability across different methods may limit clinical utility and complicate the interpretation of results due to uncertainty in elastographic measurements. This study evaluates the performance of wave-based air-pulse optical coherence elastography (OCE), air-coupled ultrasound (ACUS) OCE, piezoelectric (PZT) OCE, quasistatic compression OCE, ultrasound-based shear wave elastography (USWE), and Brillouin imaging against the benchmark standard of uniaxial mechanical testing. The absolute percentage difference of Young’s modulus was calculated between uniaxial mechanical testing and all elastography methods. Bland-Altman analysis was utilized to identify systematic biases and levels of agreement. The results show that wave-based OCE methods (air-pulse, ACUS, and PZT) agree well with each other and with mechanical testing. The degree of variability was greater in USWE and compression OCE. However, wave-based OCE had a lower degree of variability, while USWE demonstrated the least overall error when compared with uniaxial mechanical testing results. Brillouin imaging showed a strong correlation (R = 0.96) with uniaxial mechanical testing measurements. However, because its link to Young’s modulus is not direct without knowledge of the refractive index and density, it was not compared. The findings from this comprehensive approach will facilitate further research into optimizing elastography technologies, allowing for more accurate, consistent, and reproducible measurements of tissue elasticity across diverse applications.

.SignificanceEstimating biomechanical properties of the in vivo crystalline lens remains a challenge and is a barrier to evaluating novel lens softening therapies. There is a need to estimate quantitative biomechanical properties of the human anterior and mid segments of the eye in vivo for conditions such as presbyopia.AimWe aim to develop a multimodal elastography device that enables high-performance sequential 3D imaging with both Brillouin microscopy and optical coherence elastography (OCE).ApproachWe combined Brillouin spectroscopy and OCE on a modified slit lamp platform for human measurements. The multimodal system was first characterized and then tested on both a porcine eye and a human subject.ResultsBoth OCE and Brillouin microscopy were characterized at peak operating performance for clinical imaging. Successful measurements of an in situ porcine lens and a human in vivo lens are reported.ConclusionWe demonstrated the first successful multimodal OCE and Brillouin microscopy measurement in a human subject. This instrument offers the potential to characterize the biomechanical status of presbyopia with age.

Bimodal ex vivo biomechanical characterization of corneal UVA-crosslinking via optical coherence elastography and nanoindentation under physiological conditions.

Low-energy femtosecond laser lens fragmentation techniques for cataract.

Purpose:This study provides a bibliometric analysis of global research on anterior segment optical coherence tomography (AS-OCT) in corneal diseases, mapping key research trajectories, collaborations, and emerging trends.Methods:A systematic search in the Web of Science Core Collection on January 1, 2025, retrieved 3634 records (1994–2024). After excluding non-English publications, non-ophthalmology studies, and non-corneal research, 2079 publications were analyzed using VOSviewer and CiteSpace for citation networks, coauthorship trends, and keyword co-occurrence.Results:AS-OCT research has grown significantly (Mann–Kendall τ = 0.929, P < .001). The United States led in publications (639 papers, 19,594 citations), followed by China (333 papers, 4502 citations). The University of California was the most productive institution. The first AS-OCT study, published in the Archives of Ophthalmology (1994) by Izatt JA et al, marked the field’s inception. The most cited article was Huang et al’s 1991 Science paper on optical coherence tomography. Recent trends highlight the integration of artificial intelligence, deep learning, and optical coherence elastography in AS-OCT applications. The top 3 contributing journals were Cornea, Journal of Refractive Surgery, and Journal of Cataract and Refractive Surgery. Coauthorship analysis identified Jodhbir S. Mehta and David Huang as central figures in AS-OCT research collaborations.Conclusion:AS-OCT research has expanded significantly, enhancing diagnostics, surgical planning, and disease monitoring. Artificial intelligence-driven analytics and optical coherence elastography are promising future directions. This bibliometric analysis guides advancing AS-OCT research and clinical applications.

To determine the biomechanical properties of the central corneal region under intraocular pressure (IOP) and to develop an accurate method for predicting the corresponding responses. In the rabbit corneal inflation test, a calculation method for the biomechanical properties in the thickness direction of the cornea was proposed. The corresponding stress-strain relationship was obtained from the change in the central corneal thickness and IOP. Finite element analysis (FEA) was utilized to predict the biomechanical responses of the central corneal region under IOP using the derived stress-strain relationship. The FEA predictions using the stress-strain relationships derived fromtheuniaxial tensile test and optical coherence elastography (OCE) were also conducted for comparison. The prediction accuracy of the FEA based on the inflation test was evaluated against OCE (in-plane), OCE (out-of-plane), and uniaxial tensile test. Compared to these methods, the maximum deviation of the apex displacement prediction based on the inflation test decreased by 73.2, 88.4, and 64.4%, respectively, and the maximum deviation of the central curvature prediction decreased by 89.2, 30.7, and 49.7%, respectively. The stress-strain relationship in the thickness direction of the cornea can provide the most accurate prediction result of the corneal biomechanical responses under IOP. The inflation test-based method proposed can serve as an accurate tool for biomechanical characterization of the central corneal region.

Systemic sclerosis (SSc) is a chronic autoimmune disease characterized by fibrosis, vascular dysfunction, and immune dysregulation, leading to significant morbidity and mortality. Noninvasive imaging techniques are critical for monitoring disease progression and evaluating therapeutic interventions. This study investigates the technical feasibility of multifunctional optical coherence tomography (OCT)-based methods for longitudinal assessment of skin thickness, stiffness, and microvasculature in a murine SSc model as a translational, noninvasive, and quantitative method to study disease progression and treatment response. Our findings demonstrate significant structural, biomechanical, and vascular changes in the skin's stiffness, indicative of fibrosis, a hallmark of SSc. The application of SB 525334 (a transforming growth factor β1 receptor ALK5 inhibitor) mitigated these changes, highlighting its potential as a treatment strategy. Despite the inherent limitations of the mouse model in replicating the complexity of SSc, this study introduces a new technique for investigating the SSc pathogenesis and evaluating the efficacy of potential SSc therapies. These results encourage further exploration of the multifunctional Optical Coherence Elastography and OCT Angiography for monitoring disease progression and treatment response in SSc. In summary, bleomycin treatment significantly increased skin thickness, stiffness, and vessel lumen width, while SB 525334 partially reversed these changes, demonstrating the feasibility of our multifunctional OCT approach for monitoring experimental SSc.

Riboflavin/UV-A corneal collagen cross-linking (CXL) is a standard treatment for early-stage keratoconus. However, quantitative CXL outcomes remain limited. This study evaluated CXL effects on outflow facility and corneal biomechanics at intraocular pressures (IOPs) in exvivo porcine eyes. Ocular rigidity and outflow facility were derived from pressure-volume and IOP decay curves using a direct manometric technique, while corneal elasticity (Young's modulus) was measured via non-contact air-pulse optical coherence elastography. CXL increased ocular rigidity (0.0066 ± 0.0001 μL-1 vs. 0.0060 ± 0.0002 μL-1) and reduced outflow facility from 0.5429 ± 0.0320 to 0.1485 ± 0.0153 μL/min/mmHg (20-40 mmHg), compared to 0.7327 ± 0.0894-0.2210 ± 0.0502 μL/min/mmHg in untreated eyes. Young's modulus increased by 92%, 89%, and 155% at 20, 30, and 40 mmHg. These findings enhance our understanding of flow dynamics at IOP levels, suggesting that outflow facility and corneal biomechanics may serve as potential indicators for evaluating the effectiveness of CXL.

.SignificanceOptical coherence elastography (OCE) is a noninvasive imaging technique with high sensitivity and resolution that can be used for mucocutaneous imaging. Oral submucous fibrosis (OSF) is a chronic disease that has a tendency to become cancerous. Nevertheless, there are a few noninvasive methods for early detection of OSF.AimA piezoelectric transducer-based (PZT) OCE technique was devised to noninvasively assess the structural and mechanical properties of mucosa in healthy and fibrotic oral diseases.ApproachWe first validated the accuracy and reliability of the OCE system for tissue elasticity detection by means of a heterogeneous agar model. The structural and biomechanical characteristics of the regional tissues were then evaluated by examining the oral mucosa of both healthy and fibrotic SD rats.ResultsNormal and fibrotic tissue stiffness differed significantly (). The elastic wave velocity was in the normal group and in the fibrotic group. After converting the results to Young’s modulus, the stiffness of the healthy buccal tissues and the fibrotic buccal tissues were and , respectively ().ConclusionsOCE can differentiate between normal and fibrotic tissue based on elasticity and optical properties. Healthy buccal tissues were softer than diseased tissues.

Quantitative analysis of viscoelastic alterations in oral submucous fibrosis (OSF) provides crucial insights for monitoring disease progression and preventing malignant transformation. We developed a piezoelectric-based optical coherence elastography (OCE) system for real-time, in vivo quantitative assessment of OSF progression. In our experimental model, sixteen rats were systematically divided into four groups representing progressive fibrosis stages. Phase-sensitive OCE measurements captured distinctive elastic wave propagation patterns across all experimental groups. Comprehensive analysis of phase velocity dispersion curves and wave attenuation enabled the extraction of quantitative viscoelastic parameters that reflect fundamental tissue changes. Results demonstrated significant biomechanical alterations with disease progression, most notably a nearly four-fold increase in Young’s modulus from normal tissue (32.6 ± 3.9 kPa) to severe fibrosis (121.1 ± 9.9 kPa), accompanied by more than doubled viscosity coefficients (0.52 ± 0.06 Pa·s to 1.27 ± 0.15 Pa·s). Particularly significant was the loss factor (G"/G′) pattern, which exhibited a non-monotonic trend—decreasing from 0.30 in control specimens to 0.18 in moderate fibrosis groups before slightly increasing to 0.20 in severe fibrosis groups. The viscoelastic parameters quantified by OCE may facilitate more precise staging of OSF and potentially provide early indicators for assessing progression risk toward malignancy.

.SignificanceGlaucoma is a leading cause of irreversible blindness, characterized by progressive optic nerve damage. Early detection of glaucoma is key to effective intervention, but an incomplete clinical understanding of the development of glaucoma complicates the selection of diagnostic criteria. Prolonged ocular hypertension due to glaucoma can impact the biomechanical properties of ocular tissues, including the cornea. We examine whether experimental glaucoma causes changes in the biomechanical properties of the cornea.AimWe determined the biomechanical properties of the cornea in a nonhuman primate model of unilateral experimental glaucoma and compared them with the fellow, untreated control eyes using optical coherence elastography (OCE) to determine if prolonged intraocular pressure (IOP) elevation causes changes in corneal stiffness.ApproachExperimental glaucoma was induced in one eye (Macaca mulatta, ) by lasering the trabecular meshwork, whereas the fellow eye was used as a control. Both eyes were imaged with wave-based OCE to investigate the inter-ocular difference in stiffness. Measurements were taken at three different frequencies with quasi-harmonic excitation, and central corneal thickness was measured along with IOP in each eye.ResultsOur results show a significant () increase in wave speed in the experimental glaucoma eye compared with the control eye for both subjects.ConclusionsThese results show the potential of wave-based OCE methods for assessing stiffness changes in the cornea caused by remodeling due to chronic pressure elevation.

.SignificanceAccurate estimation of hydrogel phantom elasticity in 3D cell culture systems provides valuable insights into cellular responses to various mechanical stimuli. Although reverberant wave elastography has been applied to measure hydrogel elasticity in 3D cell cultures using multi-point loading, achieving a high-quality reverberant displacement field remains critical for accurate reverberant wave elastography.AimWe develop an innovative approach using 3D-printed randomly distributed scatterers to improve displacement field quality in reverberant wave elastography, inspired by scattering-coded architectured boundaries in object localization.ApproachNumerical simulations were performed to analyze the reverberant displacement fields under various loading conditions. The results were compared to determine the optimal loading configuration to enhance the reverberation level of the displacement field. Subsequently, both numerical and experimental reverberant wave elastography were carried out to validate the elasticity measurement with 3D-printed randomly distributed scatterers.ResultsThe comparison of reverberant displacement patterns under various loading conditions revealed that the displacement pattern under circular loading with 64 scatterers most closely approximated a diffuse wave field, exhibiting both spatial uniformity and directional isotropy. Numerical reverberant wave elastography was subsequently performed, successfully demonstrating its capability for elasticity measurements. Furthermore, the shear wave speeds obtained through optical coherence elastography showed good agreement with shear rheometry measurements.ConclusionsThe developed 3D-printed randomly distributed scatterers successfully enhanced the quality of the reverberant displacement field for reverberant wave elastography. Our approach presents a novel and promising tool for quantifying tissue elasticity in reverberant wave elastography applications.

Early diagnosis of skin lesions is crucial for improving treatment outcomes. So far, based on optical coherence tomography (OCT), as a non-invasive technique, OCT structural image, optical coherence elastography (OCE), and OCT-based angiography (OCTA) have been utilized to evaluate the biomechanical properties and vascular network in in-vivo human skin. However, image registrations are the major difficulty in separating scans. Therefore, the integration of these three modalities has been achieved by a new scanning protocol to provide a comprehensive, non-invasive assessment of skin tissue, enabling more accurate differentiation between benign and malignant lesions. This study aimed to collect data for the OCT structure, OCE, and OCTA in one scanning acquisition by employing a swept-source (SS-OCT) OCT system. Eleven health participants were recruited for three positions: palm (n = 11), forearm (n = 11), and facial skin (n = 5). From OCE data, Young’s modulus was calculated for the stiffness; from OCTA data, vessel area density (VAD), vessel skeleton density (VSD), vessel diameter index (VDI), and weighted Tortuosity Index (WTI) were used to evaluate the vessel network. One facial lesion dataset was collected, and the results indicated differences in the above parameters compared to healthy facial skin data. In conclusion, the new scanning protocol for integrating the structural image, OCE, and OCTA in one scan demonstrated results to calculate the parameters of the skin, which provides potential benefits for skin research and offers full aspects for dermatologists of skin disease.

Quantifying Lesion Biomechanics During Oral Carcinogenesis Via Optical Coherence Elastography

Impact of multiplicative noise removal on digital volume correlation-based optical coherence elastography

Current methods for assessing corneal mechanical properties are limited, particularly in their ability to provide localized information. This study proposes a novel approach based on the spectroscopic magnetomotive optical coherence elastography (MM-OCE) technique, aiming to enable non-invasive, localized evaluation of corneal mechanical properties. Magnetic nanoparticles (MNPs) were distributed on sample surfaces to induce vibrations via magnetic excitation. A spectral-domain OCT system combined with phase-sensitive OCT analysis tracked mechanical responses. Gelatin phantoms (varying stiffness) and ex vivo porcine corneas (untreated vs. crosslinked [CXL] regions) were tested. MB-mode validated MNP-induced vibrations, while M-mode scans and spectral analysis determined resonance frequencies. Histology assessed tissue integrity post-MNP application. Gelatin resonance frequencies increased with concentration, confirming sensitivity to mechanical variations. In corneas, MM-OCE detected significant differences between untreated and CXL-treated regions: resonance frequencies rose from 74.48 ± 6.23 Hz (untreated) to 83.42 ± 4.97 Hz (1-min UV), 110.92 ± 2.40 Hz (3-min UV), and 121.23 ± 3.02 Hz (6-min UV). Histology confirmed no MNP-induced tissue damage. MM-OCE effectively differentiates localized biomechanical changes in corneal tissue, demonstrating feasibility for quantifying stiffness variations induced by CXL. Although further improvements are needed for potential clinical applications, this study demonstrated that MM-OCE may offer a promising, non-invasive method for assessing local mechanical properties of a cornea, with the potential to enhance early diagnosis, treatment planning, and monitoring in ophthalmology.

.SignificanceThe stiffness and compliance of biological tissues are key properties that often change in the presence of pathology, yet current shear wave elastography approaches using optical coherence tomography (OCT) face limitations due to slow image acquisition, sensitivity to motion artifacts, and reliance on advanced hardware, hindering clinical translation.AimThe aim is to develop and validate a practical, high-speed method for three-dimensional shear wave imaging compatible with standard OCT systems and wave propagation variability.ApproachWe introduce a technique for the rapid, asynchronous acquisition of three-dimensional shear wave fields. Our technique operates at conventional acquisition rates and utilizes pairs of B-scans, similar to angiography scanning protocols. This approach significantly reduces motion sensitivity and enhances acquisition speed, even with much denser lateral sampling. In addition, we present a technique for estimating the shear wave number, termed directional phase gradient analysis. This method computes the phase gradient of the autocorrelation of the directionally-filtered, complex-valued shear wave and is robust across unidirectional, partially diffuse, and fully diffuse shear wave conditions.ResultsWe validated the accuracy of our techniques through direct comparison with phase-locked, synchronous-mode imaging in benchtop experiments using tissue-mimicking phantoms. Furthermore, we demonstrated their robustness to variations in wave orientation, excitation amplitude, and diffusivity, as confirmed by repeated measurements on the same sample under diverse conditions.ConclusionsTogether, these methods may offer a more practical approach for shear wave imaging without requiring modifications to existing clinical phase-stable OCT systems.