광 결맞음 단층촬영법을 이용한 조직의 탄성도 측정을 위한 예비실험

권다영(Daa Young Kwon),안예찬(Yeh-Chan Ahn),옥철호(Chulho Oak),박은기(Eun-Kee Park) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12

동적 광단층 탄성영상법을 이용한 조직의 고해상도 기계적 성질 측정을 위한 예비 실험

권다영,안예찬,Kwon, Daa Young,Ahn, Yeh-Chan 한국광학회 2018 한국광학회지 Vol.29 No.3

동적 광단층 탄성영상법은 광 결맞음 단층촬영법을 기반으로 하여 위상차에 의해 조직의 기계적 성질 중 하나인 탄성도를 측정하기 위한 기법이다. 광 결맞음 단층촬영법은 마이켈슨 간섭계를 기반으로 한 비침습적 고해상도 단면 촬영기법이다. 본 논문에서는 광단층 탄성영상법을 생체 조직에 적용하기 전에 실행가능성을 판단하고자 강도를 쉽게 구분할 수 있는 지우개, 스펀지, 샤프심으로 샘플을 제작하여 실험을 진행하였다. 샘플에 사인파의 일정한 진동자극을 가하기 위해 압전액추에이터를 샘플의 아래쪽에 위치시켰으며 위쪽에서 광 결맞음 단층촬영법으로 스캔하였다. 깊이마다 횡방향에 대한 변형속도를 힐버트 변환하여 포락선을 검출한 후 포락선의 높낮이를 색깔로 표현하여 이미지 상에서 샘플 내의 상대적인 강도를 비교할 수 있었다. 또한, 샘플단과 참조단 사이의 간섭을 이용하는 것보다 샘플단 내의 자기간섭을 이용할 경우 변형속도 계산에 있어 장점이 있음을 제시하였다. Optical coherence elastography (OCE) is based on optical coherence tomography (OCT), which is a noninvasive, high-resolution, cross-sectional imaging technique. In this paper, we have developed dynamic optical coherence elastography to measure elasticity, a mechanical property of tissue, by phase difference. A piezoelectric actuator was used for sinusoidal mechanical loading of samples. Before applying this method to biomaterial, we assessed the feasibility of OCE with samples of sponge, eraser, and sharp lead. Cross-sectional and phase-difference images of the sample were obtained under sinusoidal loading. The strain rate was calculated from the phase-difference information. To obtain the envelope of the phase-difference oscillations along the horizontal direction, Hilbert transformation was performed at each depth. The elevation of the envelope was represented by color mapping, and we could measure the relative elasticity within the sample by comparing the elevations. Finally, there was an advantage when we calculated the shear rate using self-interference in the sample arm, instead of the interference between sample and reference arms.

Investigation of the Clinical Potential of Polarization-Sensitive Optical Coherence Tomography in a Laryngeal Tumor Model

Xin Zhou,Kim Sung Won,Oak Chulho,Kwon Daa Young,Choi Jin Hyuk,Ko Taek Yong,Kim Jun Hyeong,Tang Shuo,Ahn Yeh-Chan 한국조직공학과 재생의학회 2021 조직공학과 재생의학 Vol.18 No.1

BACKGROUND: The vocal cord tissue consists of three anatomical layers from the surface to deep inside: the epithelium that contains almost no collagen, the lamina propria that is composed of abundant collagen, and the vocalis muscle layer. It is clinically important to visualize the tissue microstructure using a non-invasive method, especially in the case of vocal cord nodules or cancer, since histological changes in each layer of the vocal cord cause changes in the voice. Polarization-sensitive optical coherence tomography (PS-OCT) enables phase retardation measurement to evaluate birefringence of tissue with varied organization of collagen fibers in different tissue layers. Therefore, PS-OCT can visualize structural changes between normal and abnormal vocal cord tissue. METHOD: A rabbit laryngeal tumor model with different stages of tumor progression was investigated ex-vivo by PS-OCT. A phase retardation slope-based analysis, which quantifies the birefringence in different layers, was conducted to distinguish the epithelium, lamina propria, and muscle layers. RESULTS: The PS-OCT images showed a gradual decrease in birefringence from normal tissue to advanced tumor tissue. The quantitative analysis provided a more detailed comparison among different stages of the rabbit laryngeal tumor model, which was validated by the corresponding histological findings. CONCLUSION: Differences in tissue birefringence was evaluated by PS-OCT phase retardation measurement. It is also possible to indirectly infer the dysplastic changes based on the mucosal and submucosal alterations. BACKGROUND: The vocal cord tissue consists of three anatomical layers from the surface to deep inside: the epithelium that contains almost no collagen, the lamina propria that is composed of abundant collagen, and the vocalis muscle layer. It is clinically important to visualize the tissue microstructure using a non-invasive method, especially in the case of vocal cord nodules or cancer, since histological changes in each layer of the vocal cord cause changes in the voice. Polarization-sensitive optical coherence tomography (PS-OCT) enables phase retardation measurement to evaluate birefringence of tissue with varied organization of collagen fibers in different tissue layers. Therefore, PS-OCT can visualize structural changes between normal and abnormal vocal cord tissue. METHOD: A rabbit laryngeal tumor model with different stages of tumor progression was investigated ex-vivo by PS-OCT. A phase retardation slope-based analysis, which quantifies the birefringence in different layers, was conducted to distinguish the epithelium, lamina propria, and muscle layers. RESULTS: The PS-OCT images showed a gradual decrease in birefringence from normal tissue to advanced tumor tissue. The quantitative analysis provided a more detailed comparison among different stages of the rabbit laryngeal tumor model, which was validated by the corresponding histological findings. CONCLUSION: Differences in tissue birefringence was evaluated by PS-OCT phase retardation measurement. It is also possible to indirectly infer the dysplastic changes based on the mucosal and submucosal alterations.

Application of Polarization Sensitive-Optical Coherence Tomography to the Assessment of Phase Retardation in Subpleural Cancer in Rabbits

Park Jung-Eun,Xin Zhou,Kwon Daa Young,Kim Sung Won,Lee Haeyoung,Jung Min-Jung,Tang Shuo,Ko Taek Yong,Choi Jin Hyuk,Kim Jun Hyeong,Ahn Yeh-Chan,Oak Chulho 한국조직공학과 재생의학회 2021 조직공학과 재생의학 Vol.18 No.1

Background: Polarization sensitive-optical coherence tomography (PS-OCT) provides the unique advantage of being able to measure the optical characteristics of tissues by using polarized light. Although the well-organized fibers of healthy muscle can change the polarization states of passing light, damaged tissue has different behaviors. There are studies on optical imaging methods applied to the respiratory organs; however, they are restricted to structural imaging. In particular, the intercostal muscle situated under the pleura is very challenging to visualize due to the difficulty of access. Method: In this study, PS-OCT was used to identify subpleural cancer in male New Zealand white rabbits (3.2–3.4 kg) and to assess the phase retardation changes in normal and cancerous chest walls. VX2 cell suspension was injected between the intercostal muscle and parietal pleura and a tented area was observed by thoracic scope. A group of rabbits (n = 3) were sacrificed at day 7 after injection and another group (n = 3) at day 14. Results: In the PS-OCT images, pleura thickness changes and muscle damage were criteria to understand the stages of the disease. The results of image and phase retardation analysis matched well with the pathologic examinations. Conclusion: We were able to visualize and analyze subpleural cancer by PS-OCT, which provided structural and functional information. The measured phase retardation could help to identify the margin of the tumor. For further studies, various approaches into other diseases using polarization light are expected to have positive results. Background: Polarization sensitive-optical coherence tomography (PS-OCT) provides the unique advantage of being able to measure the optical characteristics of tissues by using polarized light. Although the well-organized fibers of healthy muscle can change the polarization states of passing light, damaged tissue has different behaviors. There are studies on optical imaging methods applied to the respiratory organs; however, they are restricted to structural imaging. In particular, the intercostal muscle situated under the pleura is very challenging to visualize due to the difficulty of access. Method: In this study, PS-OCT was used to identify subpleural cancer in male New Zealand white rabbits (3.2–3.4 kg) and to assess the phase retardation changes in normal and cancerous chest walls. VX2 cell suspension was injected between the intercostal muscle and parietal pleura and a tented area was observed by thoracic scope. A group of rabbits (n = 3) were sacrificed at day 7 after injection and another group (n = 3) at day 14. Results: In the PS-OCT images, pleura thickness changes and muscle damage were criteria to understand the stages of the disease. The results of image and phase retardation analysis matched well with the pathologic examinations. Conclusion: We were able to visualize and analyze subpleural cancer by PS-OCT, which provided structural and functional information. The measured phase retardation could help to identify the margin of the tumor. For further studies, various approaches into other diseases using polarization light are expected to have positive results.