Dataset Information

Simultaneous tensile and shear measurement of the human cornea in vivo using S0- and A0-wave optical coherence elastography.

ABSTRACT: Understanding corneal stiffness is valuable for improving refractive surgery, detecting corneal abnormalities, and assessing intraocular pressure. However, accurately measuring the elastic properties, particularly the tensile and shear moduli that govern mechanical deformation, has been challenging. To tackle this issue, we have developed guided-wave optical coherence elastography that can simultaneously excite and analyze symmetric (S0) and anti-symmetric (A0) elastic waves in the cornea at frequencies around 10 kHz and allows us to extract tensile and shear properties from measured wave dispersion curves. By applying acoustoelastic theory that incorporates corneal tension and a nonlinear constitutive tissue model, we verified the technique using elastomer phantoms and ex vivo porcine corneas and investigated the dependence on intraocular pressure. For two healthy human subjects, we measured a mean tensile modulus of 3.6 MPa and a mean shear modulus of 76 kPa in vivo with estimated errors of < 4%. This technique shows promise for the quantitative biomechanical assessment of the cornea in a clinical setting.

SUBMITTER: Li GY

PROVIDER: S-EPMC10441437 | biostudies-literature | 2023 Aug

REPOSITORIES: biostudies-literature

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Simultaneous tensile and shear measurement of the human cornea <i>in vivo</i> using S0- and A0-wave optical coherence elastography.

Li Guo-Yang GY Feng Xu X Yun Seok-Hyun SH

ArXiv 20230810

Understanding corneal stiffness is valuable for improving refractive surgery, detecting corneal abnormalities, and assessing intraocular pressure. However, accurately measuring the elastic properties, particularly the tensile and shear moduli that govern mechanical deformation, has been challenging. To tackle this issue, we have developed guided-wave optical coherence elastography that can simultaneously excite and analyze symmetric (S0) and anti-symmetric (A0) elastic waves in the cornea at fre ...[more]

PMID: 37608935

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Project description:Objectives:The aim of the study was to compare elastographic means in parathyroid adenomas, using shear wave elastography and strain elastography. Methods:This prospective study examined 20 consecutive patients diagnosed with primary hyperparathyroidism and parathyroid adenoma, confirmed by biochemical assay, technetium-99 sestamibi scintigraphy, and pathology report, after parathyroid surgery. All patients were examined on conventional 2B ultrasound, 2D shear wave elastography, and strain elastography. We determined using 2D shear wave elastography (SWE) the elasticity index (EI) in parathyroid adenoma, thyroid parenchyma, and surrounding muscle and examined using strain elastography the parathyroid adenoma, and determined the strain ratio with the thyroid tissue and muscle tissue. Results:All patients had positive sestamibi scintigraphy and underwent surgery, with confirmation of parathyroid adenoma in all cases. The mean parathormone (PTH) value before surgery was 153.29?pg/ml (36.5, 464.8) and serum calcium concentration was 10.5?mg/dl (9, 11.5). We compared using 2D-SWE and strain elastography parathyroid adenoma with thyroid tissue and with surrounding muscle. The mean EI measured by SWE in parathyroid adenoma was 4.74?±?2.74?kPa and in thyroid parenchyma was 11.718?±?4.206?kPa (mean difference?=?6.978?kPa, p < 0.001), and the mean EI value in muscle tissue was 16.362?±?3.829?kPa (mean difference?=?11.622, p < 0.001). Using ROC analysis, we found that an EI below 7?kPa correctly identifies parathyroid tissue. We evaluated parathyroid adenomas using strain elastography by color mapping and strain ratio as a semiquantitative measurement; however, we could not find any statistical correlation comparing the strain ratio obtained from the parathyroid adenoma with the thyroid tissue (p=0.485). Conclusion:Ultrasound elastography is a helpful tool in identifying parathyroid adenomas. A cutoff value below 7?kPa can be used in 2D-SWE. Color maps in strain elastography without adding strain ratio can be used, parathyroid adenoma being identified as score 1 in the Rago criteria.

Dataset Information

Simultaneous tensile and shear measurement of the human cornea in vivo using S0- and A0-wave optical coherence elastography.

Publications

Simultaneous tensile and shear measurement of the human cornea <i>in vivo</i> using S0- and A0-wave optical coherence elastography.

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