「同調反史托克拉曼散射」光譜成像技術開發及其於臨床醫學之應用

Abstract

「同調反史托克拉曼散射」(CARS)訊號是藉由多光子與分子振動之非線性交互作用產 生。與傳統的螢光技術相比，CARS 顯微成像系統之特點在於其不需外加螢光染劑便可 產生有化學鑑別力之影像、可產生三維影像、低生物破壞性、高解析度及高靈敏度等， 極適合化學成分複雜樣品如生物系統之成像。過去一年我們建立了台灣第一套CARS 顯 微成像系統，也成功展示了混合物之化學反差成像、生物可分解高分子之三維成像、肝 組織中脂肪囊泡之高解析成像。基於這些基礎，我們提出一個三年計畫，希望進一步開 發「光譜顯微成像」之核心技術以及其於生物醫學之應用。 我們將開發以下技術: (1) 研發「CARS 內視鏡系統」:我們將整合光源至光導內視鏡及微型徑向掃瞄機制。 (2) 研發「高解析多光譜化學成像系統」:我們將以單體皮秒脈衝雷射及光子光纖用 於成像。 (3) 研發「全共振光譜化學成像系統」:我們將利用外差混頻干涉技術產生全共振光 譜訊號。 我們將進行以下生醫先期研究: (1) 探討光譜成像應用於肝臟移植手術即時評估工具之可行性。 (2) 利用光譜成像，探討分析脂肪肝病程之方法。 (3) 探討鑑定良性脂肪肝及脂肪蓄積性肝炎(steatohepatitis)之可行性。 (4) 利用光譜成像研究動脈易損斑塊(vulunable plaque)之三維化學結構與動脈粥狀 硬化之相關探討。

This proposal concerns the development and applications of a novel microscopy that is able to generate chemically specific, high resolution, 3-dimensional images while requiring no labeling. Although CARS imaging has been demonstrated on various biological systems, clinical applications of CARS have never been attempted. Concerning technical aspects, the sensitivity of CARS is limited by non-resonant signal of the surrounding medium. This could hinder the application of CARS to biological samples that is generally immersed in medium. Besides, most CARS images are associated with merely a single Raman band and the information provided is quite limited. A spectroscopic, all-resonant CARS imaging will greatly enrich the information and facilitate the applications to biological systems of great complexity. My long-term goal is to explore the potential of utilizing CARS microscopy/spectroscopy as a clinical diagnostic device. I am seeking for three-year support to develop CARS spectroscopic microscopy and to carry out pre-clinical studies on existing clinical issues. (1) No tool other than time-consuming biopsy is available for medical doctors to judge the suitability of a donor liver during surgery of liver transplant. We will examine the feasibility of utilizing CARS as an intra-operational diagnosis. (2) No tool allows to monitor the progression of a fatty liver and/or to distinguish a benign fatty liver from steatohepatitis. We will employ spectroscopic CARS imaging to liver tissues of patients at different stages hoping to uncover the underlying biochemical aspects. (3) We will carry out CARS and other nonlinear microscopy to reveal the spatial-chemical aspect of vulnerable atherosclerotic plaques that compose of a lipid core covered by a thin fibrous cap. This could potentially become another useful modality to a cardiovascular catheter for the early diagnosis and treatment of cardiovascular diseases. Parallel to the above clinical applications, we will also focus on the development of CARS imaging. We will develop (1) a compact, single-laser CARS imaging system; (2) multiplex spectroscopic CARS imaging; and (3) all resonant heterodyne CARS imaging. Our group is the only research team in Taiwan that has demonstrated CARS imaging. In the past year, we have completed the first CARS setup and demonstrated CARS imaging on polymeric materials and biological samples. We have carried out some preliminary studies to justify the proposed work here. All these should serve a concrete foundation for the success of our project. The advancement of CARS microscopy is still in its early stage. We are just about to catch the frontier in this field. The applications we propose here are of great importance but have never been explored. The generous and timely support from NSC (The College of Science at the National Chiao Tung University has agreed to provide matching money amounts to NT eight million dollars to this project) will definitely help us to establish a leading position in this unexplored field. More importantly, any positive outcome generated from this pre-clinical study may lead to the birth of new diagnostic tools and bring in tremendous benefit to the human being.