Quantitative Assessment of Hyaline Cartilage Elasticity during Optical Clearing using Optical Coherence Elastography

Quantitative Assessment of Hyaline Cartilage Elasticity during Optical Clearing using Optical Coherence Elastography

Chih-Hao Liu1, Manmohan Singh1, Jiasong Li1, Zhaolong Han1, Chen Wu1, Shang Wang2, Rita Idugboe1, Raksha Raghunathan1, Valery P. Zakharov3, Emil N. Sobol4, Valery V. Tuchin3,5,6, Michael Twa7, and Kirill V. Larin1,3,5,6+

1Department of Biomedical Engineering, University of Houston, 3605 Cullen Boulevard, Houston, Texas 77204 USA2Department of Molecular Physiology and Biophysics, Baylor College of Medicine, One Baylor Plaza, Houston, Texas, 77030 USA3Department of Electrical Engineering, Samara State Aerospace University, Samara, 443086 Russia4Department of Physics, Moscow State University, Moscow, 119991 Russia 5Department of Optics and Biophotonics, Saratov State University, Saratov, 410012 Russia6Interdisciplinary Laboratory of Biophotonics, Tomsk State University, Tomsk 634050 Russia7College of Optometry, University of Houston, 505 J.Davis Armistead Bldg., Texas 77204 USA

+ Corresponding author: klarin@uh.edu

Motivation

[1] M. G. Stewart, T. L. Smith, E. M. Weaver et al., Outcomes after nasal septoplasty: results from the Nasal Obstruction Septoplasty Effectiveness (NOSE) study, Otolaryngology--Head and Neck Surgery, 130(3), 283-290 (2004).[2] E. Sobol, A. Sviridov, V. Svistushkin et al., "Feedback controlled laser system for safe and efficient reshaping of nasal cartilage." 7548, 75482H-75482H-5.[3] E. Sobol, A. Sviridov, A. Omelchenko et al., Laser reshaping of cartilage, Biotechnology and Genetic Engineering Reviews, 17(1), 553-578 (2000).[4] D. E. Protsenko, A. Zemek, and B. J. F. Wong, Temperature dependent change in equilibrium elastic modulus after thermally induced stress relaxation in porcine septal cartilage, Lasers in Surgery and Medicine, 40(3), 202-210 (2008).

Laser septochondrcorrection (LSC)(non-destructive surgery)advantageSafe(bloodless, painless) non-invasive Less complication compared with traditional septoplasty surgery [1,2]Stress relaxation process Permanent deformation Change from Bound water to free water state Biomechanical property changes [3]

Fig: Scheme of Laser septochondrcorrection procedureFig: Optimal condition for laser reshaping window [3]Fig: Stress relaxation mechanism [4]

MotivationOptical clearing techniqueAn approach to monitor the change of tissue optical properties (structural information) OCT signal slope [1]HoweverThe elasticity changes of biological tissues during clearing process havent been studied yetOptical coherence elastography (OCE)Biomechanical property measurementCornea[2], soft-tissue tumor[3], cardiac muscle[4]In this workwe report the first use of OCE to monitor the elasticity changes during optical clearing process.Speckle variance analysis OCE detectionUniaxial mechanical testing

Fig. Visualization of the elastic wave propagation in ex vivo rabbit cornea[1] K. V. Larin, M. G. Ghosn, A. N. Bashkatov et al., Optical clearing for OCT image enhancement and in-depth monitoring of molecular diffusion, IEEE Journal of Selected Topics in Quantum Electronics, 18(3), 1244-1259 (2012).[2] S. Wang, and K. V. Larin, Shear wave imaging optical coherence tomography (SWI-OCT) for ocular tissue biomechanics, Optics letters, 39(1), 41-44 (2014).[3] S. Wang, J. Li, R. K. Manapuram et al., Noncontact measurement of elasticity for the detection of soft-tissue tumors using phase-sensitive optical coherence tomography combined with a focused air-puff system, Optics letters, 37(24), 5184-5186 (2012).[4] S. Wang, A. L. Lopez, Y. Morikawa et al., Noncontact quantitative biomechanical characterization of cardiac muscle using shear wave imaging optical coherence tomography, Biomedical Optics Express, 5(7), 1980-1992 (2014).

Material and methodSample preparation Two samples were width-wise extracted from the same nasal septum cartilageOCE measurementUniaxial mechanical testingOptical clearing agent1X PBS20% glucoseClearing period0-20 min: 1X PBS 21-140 min: 20% glucose

1.3cm1cmFig: The used cartilages during the optical clear experiment

Phase-stabilized swept source OCT (PhS-SSOCT) Broad band swept laser:1310nmScan range: 150nmScan rate: 30k HzThe axial resolution: ~11 mPhase stability: 16 mScan distance: 6.25mm (n=251)OCT signalPhase: Elastic wave velocityIntensity: Speckle variance Uniaxial mechanical compression testing

Fig: diagram of mechanical compression testingFig: Schematic diagram of PhS-SSOCT

Quantification of elasticity from OCE Displacement profile

Where 0 was the central wavelength of the laser source, and was the phase of OCT signal, and n was the refractive index.

Elasticity quantification:Time delay tCross-correlation analysisElastic group Velocity can be expressed as:Youngs modulus [1]:

where =1100 kg/m3 was the density of the tissue, =0.5 was the Poisson ratio [1] Shang Wang, J. Li, S. Vantipalli et al., A focused air-pulse system for optical-coherence-tomography-based measurements of tissue elasticity, Opt. Lett., 10(7), (2013).

Fig: (left) OCE setup with OCE measurement positions. (left) typical displacement profileCorresponding to the red point in (left)

Speckle variance computationSpeckle variance [1]Study the fluid kinetics during the clearing processProcedurePerform a linear fit on the OCT A-line signalThe linear fit was then subtracted from the OCT signalThe speckle variance was determined by a standard deviation of the slope removed OCT signal

[1]C.-H. Liu, J. Qi, J. Lu et al., Improvement of tissue analysis and classification using optical coherence tomography combined with Raman spectroscopy, Journal of Innovative Optical Health Sciences, 8(2), 1550006 (2014).

Fig: (left) A typical OCT A-line intensity profile with a linear fit (right) Slope-removed OCT A-line intensity profile with standard deviation bounds.

ResultSpeckle varianceKinetic glucose diffusion50-140 minOCE elasticity0-20 min (water absorbance)20-30min(Bound to free water state)30-140min(water diffused back)

Fig: (upper) Speckle variance, as quantified by the standard deviation of the slope-removed A-line intensity profile. (lower) Youngs modulus as estimated by equation (2) utilizing the elastic wave group velocity as measured by PhS-SSOCE. The cartilage sample was immersed in 1X PBS for 20min, then in 20% glucose for 120min.

Fig: Stress relaxation mechanism [1][1] E. Sobol, A. Sviridov, A. Omelchenko et al., Laser reshaping of cartilage, Biotechnology and Genetic Engineering Reviews, 17(1), 553-578 (2000).Result Quantitative value differenceAnisotropy of the biomedical properties [1]

Fig. (upper) Elasticity as measured by PhS-SSOCE and uniaxial mechanical testing. (lower) Uniaxial mechanical compression testing. The cartilage sample was immersed in 1X PBS for 20 minutes, then in 20% glucose for 120 minutes.

[1] B. J. F. Wong, K. K. H. Chao, H. K. Kim et al., The Porcine and Lagomorph Septal Cartilages: Models for Tissue Engineering and Morphologic Cartilage Research, American Journal of Rhinology, 15(2), 109-116 (2001).

Conclusion The elasticity of the cartilage DecreaseSample dehydration caused by glucose solution.IncreaseSample hydration by the water diffused back to the cartilage during mechanical compression testThe elasticity trend obtained byPhS-SSOCE uniaxial compression testThe results demonstrate the feasibility of utilizing OCE to detect and monitor the biomechanical properties during optical clearing.In Future, Viscosity change characterize the water content of the cartilage.

are in agreement Lab members

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