1. Tissue analysis of nephritic kidney using optical coherence elastography (OCE)
Chih-Hao Liu1, Manmohan Singh1, Jiasong Li1, Chen Wu1, Raksha1, Rita Idugboe1, Yong Du1, Chandra Mohan1, Michael Twa2, and Kirill V. Larin1,3
1Department of Biomedical Engineering, University of Houston
2Department of Optometry, University of Houston
3Department of Molecular Physiology and Biophysics, Baylor College of Medicine

2. What is nephritis? Conventional detection: Acute Glomerulonephritis
Anti-glomerular basement membrane disease -> cause inability to filter waste and extra fluid from the blood
Pathology:
Larger crescent formation existed in the glomeruli.
Proliferation of epithelium cells increases.
Conventional method
Ultrasound and CT Imaging
Poorer resolution (millimeter scale) and ionizing radiation[1]
Poorer correlation with histology features[2]
[1] K. V. Sharma, A. M. Venkatesan, D. Swerdlow, D. DaSilva, A. Beck, N. Jain, and B. J. Wood, “Image-guided adrenal and renal biopsy.,” Tech Vasc Interv Radiol, vol. 13, no. 2, pp. 100–109, Jun
[2] T. Sakai, F. H. Harris, D. J. Marsh, C. M. Bennett, and R. J. Glassock, “Extracellular fluid expansion and autoregulation in nephrotoxic serum nephritis in rats.,” Kidney Int, vol. 25, no. 4, pp. 619–628, Apr

3. Optical coherence elastography
OCE is a technique to measure the biomechanical properties of tissues[4-6].
Provides high spatial resolution for elasticity measurement in the order of nanometer
Minimal excitation force
Preserves function and structure of delicate tissues
Non-invasive measurement
[4]B. F. Kennedy, K. M. Kennedy, and D. D. Sampson, “A Review of Optical Coherence Elastography: Fundamentals, Techniques and Prospects,” IEEE J. Select. Topics Quantum Electron., vol. 20, no. 2, pp. 272–288.
[5]Liang, X., V. Crecea, and S.A. Boppart, Dynamic Optical Coherence Elastography: A Review.J Innov Opt Health Sci, (4): p
[6] J. Schmitt, “OCT elastography: imaging microscopic deformation and strain of tissue,” Opt. Express, vol. 3, no. 6, pp. 199–211, 1998.

4. Optical coherence elastography
Elastic group wave detection:
Texture metric -> Fluid content (diseased feature)
Induce elastic wave with focused-air pulse
Reconstruct elasticity from the elastic wave velocity
Elastic wave measurement is detail described in [7]:
The OCE measurement is in agreement with uniaxial mechanical compression testing.
(a)displacement profile of the elastic wave. (b) the measured results of gelatin.
[7]S. Wang, K. Larin, J. Li et al., “A focused air-pulse system for optical-coherence-tomography-based measurements of tissue elasticity,” Laser Physics Letters, 10(7), (2013).

5. Phase-stabilized swept source optical coherence elastography (PhS-SSOCE) system
Swept source laser: 1310 ± 75nm
Aline rate: 30 kHz/per sec
System resolution:
Axial: 11 um
Lateral: 15 um
Scanning distance: 6 mm
Phase sensitivity: 3 nm
Air-pulse force: 11 Pa
The experimental setup is
detailed in [7,8]
3.3 sensitivity in air
[8] R. K. Manapuram, V. G. R. Manne, and K. V. Larin, “Development of phase-stabilized swept-source OCT for the
ultrasensitive quantification of microbubbles,” Laser Phys., vol. 18, no. 9, pp. 1080–1086, Sep

6. Sample Preparation Mouse strain model: Protocol 129
Control x11
Nephritis x10
Protocol
The capsule of all kidney samples was removed.
The experiment was performed immediately after organ extraction.
Each sample was immersed in saline for 4 min before OCE measurement

7. Elastic wave velocity calculation
Elastic group velocity measurement
Nephritic kidney has softer
elastic Property due to:
Larger content of
proteinuria
Higher wet/dry ratio
(a) Typical OCT image of a Nephritic sample and (b) the displacement profile extracted from the red spots in (a)

8. Results and Discussion
Elastic wave velocity vs disease state. Statistical testing was performed using a two-sample t-test
In Fig. (a), it can be seen that the dispersion wave front (blue color) of the healthy kidney propagates faster than the nephritic kidney. This is due to the renal inflammation inside the cortex. The quantitative results in (b) shows that the proposed technique can efficiently detect the glomerulonephritis.

9. Future work
Develop more elasticity metrics for a better classification
Viscosity
OCT structural metrics, such as optical attenuation and spatial speckle variance.
Elastic wave amplitude attenuation

10. Reference
[1] K. V. Sharma, A. M. Venkatesan, D. Swerdlow, D. DaSilva, A. Beck, N. Jain, and B. J. Wood, “Image-guided adrenal and renal biopsy.,” Tech Vasc Interv Radiol, vol. 13, no. 2, pp. 100–109, Jun
[2]T. Sakai, F. H. Harris, D. J. Marsh, C. M. Bennett, and R. J. Glassock, “Extracellular fluid expansion and autoregulation in nephrotoxic serum nephritis in rats.,” Kidney Int, vol. 25, no. 4, pp. 619–628, Apr
[3] W. Hoddick, R. B. Jeffrey, H. I. Goldberg et al., “CT and sonography of severe renal and perirenal infections,” AJR Am J Roentgenol, 140(3), (1983).
[4]B. F. Kennedy, K. M. Kennedy, and D. D. Sampson, “A Review of Optical Coherence Elastography: Fundamentals, Techniques and Prospects,”
[5]Liang, X., V. Crecea, and S.A. Boppart, Dynamic Optical Coherence Elastography: A Review.J Innov Opt Health Sci, (4): p
[6] J. Schmitt, “OCT elastography: imaging microscopic deformation and strain of tissue,” Opt. Express, vol. 3, no. 6, pp. 199–211, 1998.
[7]S. Wang, K. Larin, J. Li et al., “A focused air-pulse system for optical-coherence-tomography-based measurements of tissue elasticity,” Laser Physics Letters, 10(7), (2013).
[8] R. K. Manapuram, V. G. R. Manne, and K. V. Larin, “Development of phase-stabilized swept-source OCT for the
ultrasensitive quantification of microbubbles,” Laser Phys., vol. 18, no. 9, pp. 1080–1086, Sep
[9]C. H. Liu, M. N. Skryabina, J. Li, M. Singh, E. N. Sobol, and K. V. Larin, “Measurement of the temperature dependence of Young's modulus of cartilage by phase-sensitive optical coherence elastography,” Quantum Electron., vol. 44, no. 8, pp. 751–756, Sep
[10]J. Li, S. Wang, R. K. Manapuram, M. Singh, F. M. Menodiado, S. Aglyamov, S. Emelianov, M. D. Twa, and K. V. Larin, “Dynamic optical coherence tomography measurements of elastic wave propagation in tissue-mimicking phantoms and mouse cornea in vivo,” J. Biomed. Opt., vol. 18, no. 12, p , Dec