Dr. Yasushi Ikuno Profile

Dr. Yasushi Ikuno

at Osaka Univ

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Author

Publications (4)

Proceedings Article | 14 March 2018 Presentation

Macular analysis by multi-contrast segmentation of retinal pigment epithelium and choroid by Jones-matrix OCT (Conference Presentation)

Shinnosuke Azuma, Shuichi Makita, Yasushi Ikuno, Masahiro Miura, Yoshiaki Yasuno

Proceedings Volume 10474, 104740A (2018) https://doi.org/10.1117/12.2288277

KEYWORDS: Optical coherence tomography, Image segmentation, Scattering, Signal attenuation, Birefringence, Angiography, Visualization, Volume segmentation, Polarization

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Proceedings Article | 19 February 2018 Presentation + Paper

Objective evaluation of choroidal melanin contents with polarization-sensitive optical coherence tomography

Masahiro Miura, Shuichi Makita, Yoshiaki Yasuno, Yasushi Ikuno, Sato Uematsu, Takuya Iwasaki, Hiroshi Goto

Proceedings Volume 10474, 104740B (2018) https://doi.org/10.1117/12.2285928

KEYWORDS: Optical coherence tomography, Eye, Polarization, Ophthalmology, Retina, In vivo imaging, Tissues, Imaging systems, Digital filtering, Computational imaging

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Proceedings Article | 8 March 2016 Paper

Accurate and quantitative polarization-sensitive OCT by unbiased birefringence estimator with noise-stochastic correction

Deepa Kasaragod, Satoshi Sugiyama, Yasushi Ikuno, David Alonso-Caneiro, Masahiro Yamanari, Shinichi Fukuda, Tetsuro Oshika, Young-Joo Hong, En Li, Shuichi Makita, Masahiro Miura, Yoshiaki Yasuno

Proceedings Volume 9697, 96971I (2016) https://doi.org/10.1117/12.2214527

KEYWORDS: Optical coherence tomography, Eye, Birefringence, Polarization, Signal to noise ratio, Optical calibration, Stochastic processes, Mathematical modeling, Monte Carlo methods, Numerical simulations, Error analysis, Skin, Neodymium, Ophthalmology, Tissues, Ions

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Polarization sensitive optical coherence tomography (PS-OCT) is a functional extension of OCT that contrasts the polarization properties of tissues. It has been applied to ophthalmology, cardiology, etc. Proper quantitative imaging is required for a widespread clinical utility. However, the conventional method of averaging to improve the signal to noise ratio (SNR) and the contrast of the phase retardation (or birefringence) images introduce a noise bias offset from the true value. This bias reduces the effectiveness of birefringence contrast for a quantitative study. Although coherent averaging of Jones matrix tomography has been widely utilized and has improved the image quality, the fundamental limitation of nonlinear dependency of phase retardation and birefringence to the SNR was not overcome. So the birefringence obtained by PS-OCT was still not accurate for a quantitative imaging.

The nonlinear effect of SNR to phase retardation and birefringence measurement was previously formulated in detail for a Jones matrix OCT (JM-OCT) [1]. Based on this, we had developed a maximum a-posteriori (MAP) estimator and quantitative birefringence imaging was demonstrated [2]. However, this first version of estimator had a theoretical shortcoming. It did not take into account the stochastic nature of SNR of OCT signal.

In this paper, we present an improved version of the MAP estimator which takes into account the stochastic property of SNR. This estimator uses a probability distribution function (PDF) of true local retardation, which is proportional to birefringence, under a specific set of measurements of the birefringence and SNR. The PDF was pre-computed by a Monte-Carlo (MC) simulation based on the mathematical model of JM-OCT before the measurement. A comparison between this new MAP estimator, our previous MAP estimator [2], and the standard mean estimator is presented. The comparisons are performed both by numerical simulation and in vivo measurements of anterior and posterior eye segment as well as in skin imaging. The new estimator shows superior performance and also shows clearer image contrast.

Proceedings Article | 4 March 2016 Presentation + Paper

Quantitative polarization and flow evaluation of choroid and sclera by multifunctional Jones matrix optical coherence tomography

S. Sugiyama, Y.-J. Hong, D. Kasaragod, S. Makita, M. Miura, Y. Ikuno, Y. Yasuno

Proceedings Volume 9693, 96930M (2016) https://doi.org/10.1117/12.2212151

KEYWORDS: Birefringence, Polarization, Optical coherence tomography, Sclera, Tissues, Scattering, Eye, Tissue optics, Diagnostics, Image segmentation, Image visualization, Optical properties

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