Publication: Visualization of melanin loss in Vogt-Koyanagi-Harada disease

Our collaborator Masahiro Miura investigated the melanin loss triggered by Vogt-Koyanagi-Harada disease (VKH) by using our Jones matrix OCT. He recently reported it in Investigative Ophthalmology & Visual Science (IOVS).

VKH is a systemic diseases characterized by whole body melanin loss. It also triggers choroidal inflammation and causes vision loss. Although the choroidal melanin property is known to be associated with the disease activity, there had not been a good tool for this investigation. Miura employed our retinal Jones matrix OCT to visualize and quantify the choroidal melanin distribution. It was found that the quantified amount of choroidal melanin is a strong identification factor of VKH activity.

The details of the study is reported in IOVS.

>> Full length article (open access)

M. Miura, S. Makita, Y. Yasuno, R. Tsukahara, Y. Usui, N.A. Rao, Y. Ikuno, S. Uematsu, T. Agawa, T. Iwasaki, and H. Goto, "Polarization-sensitive optical coherence tomographic documentation of choroidal melanin loss in chronic Vogt-Koyanagi-Harada disease," Invest. Ophthalmol. Vis. Sci. 58, 4467-4476 (2017).


東京医科大学三浦雅博教授と私たち共同で進めていた原田病のメラニン特性に関する研究の成果が米研究眼科学会の論文誌 Investigative Ophthalmology & Visual Science (IOVS) に掲載されました。

原田病は全身のメラニン減少によって特徴づけられる疾患です。このメラニンの減少は眼底の脈絡膜でもおこり、視力の低下を引き起こします。眼底におけるメラニンの量と分布が原田病診断に有用なファクターであることは知られていました。しかし、これまで、その3次元分布を可視化したり、その量を定量化したりする手法が存在しませんでした。

この研究では私たちの研究グループで開発された眼底診断用 Jones matrix OCT 装置を用いて原田病患者の眼底メラニンの観察・定量化を行いました。これによって原田病の病型の分類が可能であることが示されました。

この研究の詳細は米研究眼科学会誌 IOVS に掲載されています。

>> Full length article (open access)

M. Miura, S. Makita, Y. Yasuno, R. Tsukahara, Y. Usui, N.A. Rao, Y. Ikuno, S. Uematsu, T. Agawa, T. Iwasaki, and H. Goto, "Polarization-sensitive optical coherence tomographic documentation of choroidal melanin loss in chronic Vogt-Koyanagi-Harada disease," Invest. Ophthalmol. Vis. Sci. 58, 4467-4476 (2017).

OCT summer school in Korea

2017年9月12-13日に韓国釜山の Pukyong National University で行われた3大学合同 の OCT サマースクールに当研究室の李恩さん、東神之介君が参加しました。この サマースクールは高麗大学、光州科学技術院、筑波大学の三つの OCT 研究グループによって企画されたものです。ここでは、各大学の学生たちが実際に実験室で直面した技術課題を発表し、三つの大学の学生たちでその解決策を議論しました。また、懇親会ではメンバー全員で海鮮韓国料理に舌鼓をうちました!
　これからも年に２～３回のペースで交流を行い、国境を超えた学生ネットワークをつくろうと思います。

Our students En LI and Shinnosuke AZUMA enjoyed the first Korea-Japan OCT summer school held in Pukyong National University, Busan, Korea. The summer school was co-organized by three OCT groups at Korea University (Seoul), GIST (Gwangjoo), and University of Tsukuba (Tsukuba). The students from the three universities presented practical issues they found in the lab during their OCT work, and did extensive discussions to solve it. At last but not least, we really enjoyed amazingly delicious Korean see foods!

We hope to continue this international student workshop ever 4 to 6 months.

Tapio Fabritius 先生 ショートセミナー

University of Oulu (Finlnad) の Tapio Fabritius 教授にショートセミナーをして頂きました。

Fabritus 氏は2007-2008年にかけ Oulu 大学 からの訪問研究者として筑波大学で光干渉断層計の研究をされていました。現在は Oulu大学で printing electronics （印刷型電子回路）とその光学評価など幅広く研究をされています。

今回のセミナーでは、印刷技術を用いた微小光学素子の作成、そこで用いられる粘弾性材料の光学評価手法、作成した微小阻止の形状計測手法についてレクチャーをおこなっていただきました。

Prof. Tapio Fabritus (University of Oulu, Finland) gave a short seminar talk at COG. Tapio has been working for an optical interferometer at our group in Tsukuba from 2007-2008. He is currently working for printing electronics and its optical evaluation in University of Oulu.

He gave a lecture on optical viscosity measurement, micro-optics fabrication, and its optical testing.


2019-09-19

Publication: Superpixels for Jones matrix tomography

Our colleague Miyazawa recently reported a sophisticated method to analyze the pixel-by-pixel characteristic of multi-contrast Jones matrix optical coherence tomography (JM-OCT) images. This method makes groups of pixels based on its similarlity in optical properties and its spatial proximity. It can provide smart "kernels" to compute local statistics of OCT without sacrificing its resolution.

The details of the method is reported in Biomedical Optics Express.

>> Full length article (open access)

Citation: A. Miyazawa, Y.-J. Hong, S. Makita, D. Kasaragod, and Y. Yasuno "Generation and optimization of superpixels as image processing kernels for Jones matrix optical coherence tomography," Biomed. Opt. Express 8, 4396-4418 (2017).

技術補佐員・博士候補の宮澤氏がアメリカ光学会の論文誌 Biomedical Optics Express に論文を発表しました。これは私達が開発を進めているマルチコントラスト ジョーンズ行列トモグラフィー(JM-OCT)の新たな画像処理方である「superpixel」に関するものです。この superpixel 法は JM-OCT 画像のピクセルを、光学特性と空間的な類似性によってグルーピングしていきます。このグルーピングされたピクセル (superpixel) をさらなる画像処理の局所的な処理領域（kernel）として用いることで、画像の分解能を落とすことなる、統計処理にもとづいたJM-OCT信号の定量解析が可能になります。

>> Full length article (open access)

Citation: A. Miyazawa, Y.-J. Hong, S. Makita, D. Kasaragod, and Y. Yasuno "Generation and optimization of superpixels as image processing kernels for Jones matrix optical coherence tomography," Biomed. Opt. Express 8, 4396-4418 (2017).

Joschi, Yoshiaki Yasuno

2019-01-22 / Position opening (office assistant)

◎筑波大学安野研究室では、次のとおり年俸制職員を募集します。

【募集人員】　1名

【勤務場所】　筑波大学工学系F棟702　安野研究室

【職務内容】　医療イメージング機器研究開発プロジェクトの立案補佐、

　　　　　　　プロジェクト管理補佐（事務補佐を含む）

【応募資格】　・ワードやエクセル等のパソコン操作ができ、

　　　　　　　　職務に意欲的に取り組める方。

　　　　　　　・医療イメージング機器研究開発プロジェクトの立案補佐、

　　　　　　　　プロジェクト管理補佐の経験があり、眼科診断機器に関する

　　　　　　　　基本的な知識を持つ事が望ましい。　

【雇用期間】　平成31年4月1日～平成32年3月31日

【勤務時間】　8:30～17:15（1日7時間45分、休憩60分）

【休　　日】　土曜日、日曜日、祝日、年末年始（12月29日～1月3日）

【給　　与】　年俸制とし、年俸額の1/12を月額として支給する。

　　　　　　　いずれも本学の規定に基づき、経歴等を考慮し決定。

　　　　　　　上記の外、一定の条件を満たす場合には、通勤手当、

　　　　　　　時間外勤務手当等を支給

【有給休暇】　休暇等の制度は、本学が定める就業規則等による。

【選考方法】　書類選考後、通過者には本学で面接を行います。

【応募方法】　①履歴書：写真添付、電話番号、E-mailアドレス記載のこと

　　　　　　　②職務経歴書：様式自由（A4版に時系列で会社等名、職種、

　　　　　　　　雇用形態、週勤務日数及び時間数、職務内容を記載のこと。)

【応募締切】　平成31年1月25日（金）必着

【応募先】　　〒305-8577　つくば市天王台1-1-1

　　　　　　　筑波大学安野研究室　

　　　　　　　TEL：029-853-5217

Publication: Review article for polarization sensitive optical coherence tomography

Our colleague Yasuno recently published an review article of "polarization sensitive optical coherence tomography (PS-OCT)," which is co-authored with Prof. Johannes de Boer (VU University of Amsterdam) and Prof. Christoph Hitzenberger (Medical University of Vienna).

This article provides a comprehensive overview of PS-OCT principle, hardware implementation, signal processing, and clinical applications. If you are interested in building or using PS-OCT, this article can be a good textbook. For beginners of OCT, this article can be a good introduction of
a functional extension of OCT.

>> Full length article (open access)

Citation: J. F. de Boer, C. K. Hitzenberger, and Y. Yasuno "Polarization sensitive optical coherence tomography – a review [Invited]," Biomed. Opt. Express 8, 1838-1873 (2017).

当研究グループの安野がアムステルダム自由大学の Prof. Johannes de Boer、ウィーン医科大学の Prof. Christoph Hitzenberger と共同で偏光感受型光コヒーレンストモグラフィー （偏光OCT）のレビュー論文を発表しました。

この論文は、偏光OCTの原理、ハードウェア実装、信号処理、臨床応用までを広く解説しています。偏光OCTの作成、利用に興味のある方には最初に読む教科書として最適なものになっていると思います。また、偏光OCTにまずは興味がある、という方にも 最初に読む文献として適切なものに仕上がっていると思います。

>> Full length article (open access)

Citation: J. F. de Boer, C. K. Hitzenberger, and Y. Yasuno "Polarization sensitive optical coherence tomography – a review [Invited]," Biomed. Opt. Express 8, 1838-1873 (2017).

Publication: Motion-free eye imaging by Lissajous OCT

Our colleague Yiwei Chen has reported a new scanning technology for retinal optical coherence tomography (OCT). He used a Lissajous scan pattern to scan in vivo human retina. The Lissajous scan has significant redundancy as it scans the eye multiple times but with low density for each time. This is a perfect property to compute and estimate the eye motion occurred during the scan. By using this estimated eye motion, we correct the image deformation of the OCT occurred by the eye motion.

This technology enables motion-free OCT imaging of the eye, by which we obtain a true morphological shape of the eye. Since myopia and glaucoma are associated with eye deformation, our Lissajous OCT might have a large impact on myopia and glaucoma research/diagnosis in the future.

The details are reported in Biomedical Optics Express. (See the bottom for the link).

私達の研究グループの Yiwei Chen 研究員がモーションフリー3次元眼底イメージングを実現するための技術である「リサージュOCT」を開発史、論文発表を行いました。この技術は、リサージュと呼ばれる連続曲線パターンでOCTのプローブ光をスキャンすることで眼底の構造情報を計測します。リサージュパターン粗い密度で何度も連続的に眼底をスキャンすることを特徴としています。この特性を活かすことで、撮影中に発生した眼球の動きを算出し、OCT画像に現れる動きの影響を除去することができます。この技術を使うことで、眼球の真の形状を計測することが可能になりました。

緑内障や近視などの疾患は、眼球の形状変化を伴うことが知られています。今回開発されたリサージュOCTを用いることにより、眼球の形状の変化を高精度に追跡することが可能になります。これにより、緑内障、近視の研究や診断手法の発展が期待されます。

この研究の詳細はアメリカ光学会の論文誌 Biomedical Optics Express に掲載されました。

>> Full-length article (open access)
C. Yiwei, Y.-J. Hong,  S. Makita, and Y. Yasuno, "Three-dimensional eye motion correction by Lissajous scan optical coherence tomography," Biomed. Opt. Express 8, 1783-1802 (2017).

Publication: Multi-contrast Jones matrix OCT for skin imaging

Our colleague En Li recently reported our

development on dermatological Jones matrix optical coherence tomography (JM-OCT). This is the first full-contrast OCT for skin imaging. It is based on 1.3-um swept-source JM-OCT principle and can 3-dimensionally and non-invasively visualize the structure, vasculature, collagen and melanin of human skin by a single shot.

The technical details and skin measurement examples are published in Biomedical Optics Express.

>> Full-length article (open access)
E. Li, S. Makita, Y.-J. Hong, D. Kasaragod, and Y. Yasuno, "Three-dimensional multi-contrast imaging of in vivo human skin by Jones matrix optical coherence tomography," Biomed. Opt. Express 8, 1290-1305 (2017).

博士課程で勉強している李恩  (LI, En) さんが皮膚計測用マルチコントラスト Jones matrix 光コヒーレンストモグラフィー (JM-OCT) のに関する論文を出版しました。この論文で報告されている JM-OCT は世界で最初の皮膚科学用途に特化した Jones matrix 型 OCTです。

この装置を使うことで、一度の計測で非侵襲に生きたヒト皮膚の構造、血管、コラーゲン、メラニンの3次元形態を可視化することができます。

装置の詳細、in vivo ヒト皮膚計測結果はアメリカ光学会の論文誌 Biomedical Optics Express に掲載されています。

>> Full-length article (open access)
E. Li, S. Makita, Y.-J. Hong, D. Kasaragod, and Y. Yasuno, "Three-dimensional multi-contrast imaging of in vivo human skin by Jones matrix optical coherence tomography," Biomed. Opt. Express 8, 1290-1305 (2017).

Publication: Quantitative birefringence estimator for Jones matrix OCT

Our colleague Deepa Kasaragod has reported her new mathematical theory and numerical algorithm that give highly quantitative measurement capability to Jones matrix optical coherence tomography (JM-OCT). And hence, it enabled three-dimensional quantitative measurement of in vivo tissue birefringence.

This method is based on a maximum a-posteriori estimation theory. It first compute the probability distributions of a true signal-to-noise ratio and a true birefringence when particular measurements of a birefringence and signal-strength were occurred. The estimator finally gives the most probable true birefringence value under the measured birefringence and signal-strength by using the probability distributions.

The method was validated numerically and also experimentally by investigating in vivo human eye.
The details are reported in Biomedical Optics Express (see the bottom for a link).

当研究室の Deepa Kasaragod 研究員が新しい複屈折推定理論・アルゴリズムに関する論文を発表しました。この理論・アルゴリズムは、Jones matrix OCT で得られた「計測された複屈折値」と「計測された散乱信号強度」から「もっとも確からしい真の複屈折値」を推定するものです。これによって生体複屈折の３次元定量計測が可能になりました。

この方法は「事後分布推定」と呼ばれる理論にもとづいています。あらかじめ、特定の複屈折と信号強度が計測された際に予想される「真の複屈折強度」の確率分布を計算しておきます。そして、実際の計測後に、その確率分布から計測された試料の真の複屈折を推定する、というものです。

この手法の理論、実装の詳細と数値的検証結果、生きたヒト眼底計測に適用した結果はアメリカ光学会の論文誌 Biomedical Optics Express に掲載されています。

>> Full-length article (open access)
D. Kasaragod, S. Makita, Y.-J. Hong, and Y. Yasuno, "Noise stochastic corrected maximum a posteriori estimator for birefringence imaging using polarization-sensitive optical coherence tomography," Biomed. Opt. Express 8, 653-669 (2017).

研究室紹介

COGでの研究活動に興味のある皆様へ。

Computational Optics Group の研究紹介スライドを公開します。

2014/12/16 Joschi, Yoshiaki Yasuno

[PDF:
Optical Coherence Tomography による人体組織のトモグラフィー]

Publication: Accurate Quantification of Tissue Birefringence

Microstructures support the mechanical property of a tissue. And hence, investigating tissue microstructure has been a great interest both in the biomechanical research and for investigation of diseases associated with biomechanics, such as glaucoma. However, there was no way for in vivo quantification of tissue biomechanics. One promising approach, as we believe, is quantifying tissue birefringence for quantifying biomechanics. This approach is based on the fact that both the tissue biomechanics and birefringence are based on the same aspect of the tissue, i.e., microstructure. Our group has been working for polarization sensitive optical coherence tomography (PS-OCT) for the quantification of the biomechanics through quantitative measurement of tissue birefringence.

Since its innovation in 1997, PS-OCT was nice to qualitatively visualize the tissue birefringence. However, its quantification ability was low. It was mainly because its non-linear and complex effects of measurement noise into the birefringence values to be measured. To be honest, the raw birefringence value measured by PS-OCT has not been reliable at all.

Our colleagues Deepa Kasaragod recently developed a mathematical framework to accurately estimate the tissue birefringence from the raw birefringence values measured by PS-OCT. She first numerically characterized the relationship between the measurement noise and measured birefringence values. And then, she designed a mathematical frame work, by using a Bayesian rule together with the numerically obtained property, to obtain a “maximum likelihood estimation” of the tissue birefringence.

Both numerical and experimental validations proved that this framework has high ability to quantitate the birefringence. This method was recently published in Optics Express (full citation is shown below). In this paper, some in vivo human eye results including a pathologic case (anterior eye of trabeculectomy bleb) are presented.

Currently, a clinical study with this method is ongoing. I believe we can present impressive clinical results soon. The details of the technology are now available on the following paper.

Full length article (open access)
D. Kasaragod, S. Makita, S. Fukuda, S. Beheregaray, T. Oshika, and Y. Yasuno, Optics Express 22, 16472-16492 (2014), http://dx.doi.org/10.1364/OE.22.016472

Joschi, Yoshiaki Yasuno

Visualization of Choriocapillaris by Doppler OCT

Our colleague Kazuhiro Kurokawa reported in vivo imaging of choriocapillaris by using Doppler optical coherence tomography (Doppler OCT) equipped with adaptive optics (AO) retinal scanner. Doppler OCT have been long time utilized for the investigation of retinal vasculature. Despite of its high ability for the visualization of vasculature, it was not possible to visualize choriocapillaris mainly because of its very small dimensions. We overcame this issue by using a custom made AO retinal scanner.
      The details are presented in our recent paper in Optics Express.

>> Full length article (open access)
Citation: K. Kurokawa, K. Sasaki, S. Makita, Y.-J. Hong, and Y. Yasuno, "Three-dimensional retinal and choroidal capillary imaging by power Doppler optical coherence angiography with adaptive optics," Opt. Express 20, 22796-22812 (2012).

Scleral biomechanics and birefringence

Our colleague Masahiro Yamanari recently reported a new method for noninvasive assessment of scleral biomechanics. The biomechanics of sclera is supported by its micro-structure that is mainly formed by collagen fibers. Since the collagen fibers is known to have strong form birefringence, we may be able to assess the biomechanics by measuring the birefringence. Yamanari demonstrated significant correlation between the scleral mechanical stiffness and its birefringence which was measured by a polarization sensitive optical coherence tomography.
      You can find more details in our article on PLoS ONE.

>> Full length article on journal web site (open access)
Citation: M. Yamanari, K. Ishii, S. Fukuda, Y.H. Lim, S. Makita, M. Miura, T. Oshika, and Y. Yasuno, "Optical rheology of porcine sclera by birefringence imaging," PLoS ONE 7, e44026 (2012).

Joschi, Yoshiaki Yasuno

Quantifying Blood Flow in Choroid

Our colleague Masahiro Miura from Tokyo Medical University recently reported our first trial of quantification of choroidal blood flow. He utilized a custom made Doppler optical coherence tomography with a probe beam at 1.0-um band. The Doppler signal at the choroid was further processed with a structural structural information of the vessel. Finally an absolute velocities of choroidal blood flow in in vivo human eyes were presented.

     The details are presented in a recent issue of Investigative Ophthalmology and Visual Science.

>> Abstract and full length article on the journal web-site

Citation: M. Miura, S. Makita, T. Iwasaki, Y. Yasuno, "An approach to measure blood flow in single choroidal vessel using Doppler optical coherence tomography," Invest. Ophthalmol. Vis. Sci. 53, 7137-7141 (2012).

Step-by-step method for scientific paper writing

Yasuno recently released a short instruction article of a step-by-step method to write a scientific paper. This article was originally written to teach his students the way of scientific writing. In this instruction, he discusses a purpose of scientific writing and a detailed way to construct a logic of the paper.

The instruction is distributed under a Creative Commons Attribution No Derivatives 3.0 License (CC BY-ND 3.0), and hence you can freely read it, use it for your teaching, and also can distributed. Although you don't need to obtain any permission to use/re-distribute this document, any criticism and positive feedback are also welcome.

The document is available on the following distribution site.
>> A Card-Based Method for Scientific Paper Writing

2012-08-15

Joschi, Yoshiaki Yasuno