In Vivo Evidence of Porcine Cornea Anisotropy Using Supersonic Shear Wave Imaging

Nguyen, Thu-Mai; Aubry, Jean‐François; Fink, Mathias; Bercoff, Jérémy; Tanter, Mickaël

doi:10.1167/iovs.14-15127

Cited by 58 publications

(47 citation statements)

References 25 publications

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“…4 OCE is similar to other elastographic techniques such as ultrasound elastography (USE), 5 magnetic resonance elastography (MRE), 6 and supersonic shear wave imaging (SSI) [7][8][9] where an externally induced deformation is measured by the respective imaging modality. OCE has micrometer scale spatial resolution 10 and millisecond temporal resolution but has a limited penetration depth of a few millimeters in scattering media such as tissue.…”

mentioning

confidence: 99%

Analysis of the effects of curvature and thickness on elastic wave velocity in cornea-like structures by finite element modeling and optical coherence elastography

Han

Singh

et al. 2015

Applied Physics Letters

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Wave models that have been used to extract the biomechanical properties of the cornea from the propagation of an elastic wave are based on an assumption of thin-plate geometry. However, this assumption does not account for the effects of corneal curvature and thickness. This study conducts finite element (FE) simulations on four types of cornea-like structures as well as optical coherence elastography (OCE) experiments on contact lenses and tissue-mimicking phantoms to investigate the effects of curvature and thickness on the group velocity of an elastic wave. The elastic wave velocity as determined by FE simulations and OCE of a spherical shell section decreased from $2.8 m/s to $2.2 m/s as the radius of curvature increased from 19.1 mm to 47.7 mm and increased from $3.0 m/s to $4.1 m/s as the thickness of the agar phantom increased from 1.9 mm to 5.6 mm. Both the FE simulation and OCE results confirm that the group velocity of the elastic wave decreases with radius of curvature but increases with thickness. These results demonstrate that the effects of the curvature and thickness must be considered in the further development of accurate wave models for reconstructing biomechanical properties of the cornea. Assessing the biomechanical properties of the cornea is of great importance for detecting and monitoring the progression of ocular diseases, such as keratoconus, as well as evaluating the effectiveness of therapies, such as UVinduced collagen cross-linking. 1 In recent years, a number of noninvasive techniques have been proposed to characterize corneal biomechanical properties. For instance, the CorVis can image corneal dynamic responses from a strong air-puff stimulation, 2 and Brillouin microscopy is able to show the depth-resolved Brillouin frequency shift distribution of the cornea.3 Although these methods can provide important measurements that reflect the biomechanical characteristics of the cornea, directly quantifying the viscoelasticity of the cornea by these techniques is still a challenge.Optical coherence elastography (OCE) is a rapidly emerging method that can noninvasively measure the local biomechanical properties of tissues.4 OCE is similar to other elastographic techniques such as ultrasound elastography (USE), 5 magnetic resonance elastography (MRE), 6 and supersonic shear wave imaging (SSI) 7-9 where an externally induced deformation is measured by the respective imaging modality. OCE has micrometer scale spatial resolution 10 and millisecond temporal resolution but has a limited penetration depth of a few millimeters in scattering media such as tissue. However, penetration depth is not an issue for corneal imaging, and thus, OCE is specifically suitable for obtaining the biomechanical properties of the cornea. In our previous work, an OCE system comprised of an external noncontact loading device and an optical coherence tomography (OCT) system was utilized for tumor detection, 11 lens, 12 cornea, 13 cartilage, 14 and cardiac muscle 15 elasticity estimations. Although we have utilized a fo...

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confidence: 99%

Analysis of the effects of curvature and thickness on elastic wave velocity in cornea-like structures by finite element modeling and optical coherence elastography

Han

Singh

et al. 2015

Applied Physics Letters

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“…The high sensitivity of elastography further allows the use of micro-to nano-scale excitation that is nondestructive and therefore causes minimal influence to both structure and resident cells in engineered constructs. Furthermore, elastography has the ability to provide a high resolution 2D or 3D mapping of mechano-functional capacity of the material which can be used to deduce spatial heterogeneity 51,134 and anisotropy, 103,129 which are not accessible through traditional mechanical testing methods.…”

Section: The Value Of Elastography In Biomaterials and Tissuesmentioning

confidence: 99%

“…164 Instead of using shear waves, 103,104 the dispersion of vibration in the cornea was modeled as a surface wave propagating as a Lamb wave on a viscoelastic substrate. This approach is applicable to characterization of biomaterial substrates with thickness of less than 1 mm.…”

Section: Ultrasound Elastographymentioning

confidence: 99%

Application of Elastography for the Noninvasive Assessment of Biomechanics in Engineered Biomaterials and Tissues

et al. 2016

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The elastic properties of engineered biomaterials and tissues impact their post-implantation repair potential and structural integrity, and are critical to help regulate cell fate and gene expression. The measurement of properties (e.g., stiffness or shear modulus) can be attained using elastography, which exploits noninvasive imaging modalities to provide functional information of a material indicative of the regeneration state. In this review, we outline the current leading elastography methodologies available to characterize the properties of biomaterials and tissues suitable for repair and mechanobiology research. We describe methods utilizing magnetic resonance, ultrasound, and optical coherent elastography, highlighting their potential for longitudinal monitoring of implanted materials in vivo, in addition to spatiotemporal limits of each method for probing changes in cell-laden constructs. Micro-elastography methods now allow acquisitions at length scales approaching 5–100 μm in two and three dimensions. Many of the methods introduced in this review are therefore capable of longitudinal monitoring in biomaterials and tissues approaching the cellular scale. However, critical factors such as anisotropy, heterogeneity and viscoelasity—inherent in many soft tissues—are often not fully described and therefore require further advancements and future developments.

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“…The surface wave equation does not take into account the corneal viscoelastic nonlinearity, 25,28 corneal curvature and thickness, 29 aqueous humor, 30 dispersion of the elastic wave, 31,32 or corneal mechanical anisotropy. 24,33 Additionally, the limited spatial and temporal data points resulted in the large variance in measured corneal biomechanical properties at 20 mmHg (stiff conditions), and the limited bandwidth of the air-pulse induced waves (below 1 kHz) combined with limited number of data points prevented dispersion analysis of the elastic wave. There are still several steps for improvement, which are the focus of our future work.…”

mentioning

confidence: 99%

“…For example, utilizing the both scans of the resonant scanner, 21 dispersion analysis 31,32,34 with a more rigorous mechanical wave model 31 will enable more accurate elasticity measurements. Acoustic techniques can also provide noncontact measurement of corneal biomechanical parameters, 33 but the presence of the coupling medium can be uncomfortable for in vivo corneal applications. In this case, air-coupled acoustic radiation force excitation with ultrafast OCE shows great promise for providing truly noncontact quantification of corneal viscoelasticity.…”

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confidence: 99%

Applanation optical coherence elastography: noncontact measurement of intraocular pressure, corneal biomechanical properties, and corneal geometry with a single instrument

et al. 2017

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In Vivo Evidence of Porcine Cornea Anisotropy Using Supersonic Shear Wave Imaging

Abstract: This preliminary study demonstrates the potential of SSI for the assessment of corneal anisotropy in both ex vivo and in vivo conditions.

Cited by 58 publications

References 25 publications

Analysis of the effects of curvature and thickness on elastic wave velocity in cornea-like structures by finite element modeling and optical coherence elastography

Analysis of the effects of curvature and thickness on elastic wave velocity in cornea-like structures by finite element modeling and optical coherence elastography

Application of Elastography for the Noninvasive Assessment of Biomechanics in Engineered Biomaterials and Tissues

Applanation optical coherence elastography: noncontact measurement of intraocular pressure, corneal biomechanical properties, and corneal geometry with a single instrument

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