極化光學同調斷層攝影術之建立及其在 人體動脈粥狀硬化上之研究

The Development of Polarization Sensitive Optical Coherence Tomography and its Application on Human Atherosclerosis

郭文娟(Wen-Chuan Kuo)

指導教授 ： 鍾孝文

國立臺灣大學/電機資訊學院/電機工程學研究所/博士(2005年)

https://doi.org/10.6342/NTU.2005.10134

摘要

光學同調斷層攝影術(OCT)為一種利用低同調干涉術的原理而產生三維物體光學切片影像的重要技術，而極化光學同調斷層攝影術(PS-OCT)結合了OCT的優點再利用偵測光極化狀態的改變可獲得額外的影像對比度，此影像對比度即樣品的線性雙折射特性，(包括相位延遲角及快軸夾角兩個參數)。
　　本論文提出一種線偏極化光學同調斷層攝影術(Linear PS-OCT)，經由一先導性穿透式極化共路徑外差干涉儀對四分之一波長延遲片的線性雙折射特性二維量測實驗所延伸出來的構想。與傳統以圓偏極化為入射光的Circular PS-OCT系統比較，此新架構具有三項主要優點: (1)當樣品快軸(FA)與空間座標X軸夾角接近0度或90度時，延遲角(PR)的測量能直接由相位差得到；(2)由於環境的變化以及雷射本身頻率的漂移所造成的相位雜訊因極化外差干涉儀的共路徑特性而在相位差中相互抵消，故能得到較佳的偵測靈敏度；(3)PR及FA的量測動態範圍皆在0度到180度之間，其中延遲角的量測範圍還是傳統Circular PS-OCT的兩倍，可適用於雙折射變化特性較強的組織。
此外，我們也將Circular PS-OCT系統應用於不同型態動脈硬化斑塊的斷層造影上，經由體外(in vitro)實驗發現，可藉由延遲角的變化分辨正常血管與早期脂肪沉積以及晚期膠原纖維堆積成的纖維蓋或嚴重的鈣化等所形成的三類不同典型斑塊。並且以大量數據統計結果分析來解釋斑塊雙折射特性改變與心血管疾病發生的關聯性。若可進一步用PS-OCT對特定生化成分做定量的量測將可加速診斷區分各不同類型或不同期的動脈硬化病灶，預期PS-OCT為一極具潛力能早期偵測易破裂的斑塊的技術。

關鍵字

極化 ； 光學同調斷層攝影術 ； 動脈粥狀硬化

並列摘要

Optical coherence tomography (OCT) is a powerful tool capable of tomographic imaging based on low coherence interferometry. Polarization-sensitive optical coherence tomography (PS-OCT) combines the advantages of OCT with additional image contrast of the sample. The added contrast is based on the ability of PS-OCT to detect the birefringent properties of a sample (phase retardation and fast-axis orientation) simultaneously.
In this research, a novel linear polarization-sensitive optical coherence tomography (Linear PS-OCT) system for extracting the birefringence property of samples is proposed. This is the extended setup from our previous proposed novel polarized common-path optical heterodyne interferometer for birefringence measurement of a quarter wave plate. To compare with conventional PS-OCT which uses circular polarized incident light, the linear PS-OCT shows three advantages: (1) Phase retardation (PR) of the sample can be obtained directly from the phase-difference between the polarization heterodyne signals when the fast axis (FA) of sample is nearly parallel or orthogonal to X-axis of the coordinates; (2) Common phase noise rejection mode leads to the immunity of background phase noise and laser frequency noise at the same time that results in a higher sensitivity on PR measurements; (3) the dynamic range of PR and FA are to in which PR is two times wider than that of conventional circular PS-OCT. Therefore, the tissue of a larger birefringence variation is preferential to be arranged.
In addition, we demonstrate the Circular PS-OCT for tomographic imaging of different kinds of atherosclerotic plaques. In this in vitro study, linear birefringence change in plaque due to the prominent deposition of collagen or calcium is demonstrated by correlating PS-OCT images with histology and the use of quantitative retardation curve analysis. Thus PS-OCT (i.e., the combination of high resolution structural imaging and linear birefringence imaging) is a potentially powerful tool for early diagnosis of atherosclerotic plaque development.

並列關鍵字

polarization ； optical coherence tomography ； atherosclerosis

參考文獻

Akiba M, Chan K P and Tanno N 2000 Jpn. J. Appl. Phys. 39 L1194

Bickel W S, Davidson J F, Huffman D R and Kilkson R 1976 Proc. Natl. Acad. Sci. 73 486

Bicout D and Brosseau C 1992 J. Phys. I France 2 2047

Bracewell R N: The Fourier transform and its applications”,3rd ed. (McGraw-Hill 2000), chapter 13

Chiu M H, Chen C D and Su D C 1996 J. Opt. Soc. Am. A 13 1924