使用壓縮感知之雙波長光聲顯微技術及其於三維細胞追蹤之應用

Dual-wavelength OR-PAM with compressed sensing for cell tracking in 3D cell culture systems

黃柔軒(Rou-Xuan Huang)

指導教授 ： 李百祺

國立臺灣大學/電機資訊學院/生醫電子與資訊學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201803262

摘要

監測T細胞與腫瘤的動態交互作用有助於了解癌症免疫治療的機制。使用光學解析度光聲顯微系統來進行此類監測，不僅能提供足夠之空間解析度，也能比傳統光學顯微鏡提供較深的穿透深度。藉由外源性對比劑，此雙波長光聲顯微鏡能同時藉由523 nm雷射觀測以包矽奈米金球標定的胞殺性T細胞，並藉由800 nm雷射觀測以ICG螢光染劑標定的肝癌細胞之分布。然而，為達到足夠觀測單一細胞之空間取樣，在雷射PRF為1 kHz的情況下進行160 × 160 × 150 μm3的三維掃描範圍約需要20分鐘。為了進一步提高成像速率以有效進行細胞追蹤，我們提出一隨機稀疏取樣機制實現快速稀疏光聲數據之採集，影像重建方法則為基於壓縮感知理論下的低秩矩陣填充，透過最小核範數最佳化問題得以從顯著減少的取樣中重建回近似全取樣的高品質影像。就目前實驗結果發現光聲反應過程中的熱膨脹可能伴隨生物效應，使得細胞活性受到影響，因此仍未能追蹤細胞的動態移動。我們透過此基於壓縮感知的雙波長光學解析度光聲顯微鏡，以較高的時間解析度觀測三維腫瘤微環境中T細胞的分布，當取樣密度為0.5此系統可以減少40％的數據採集時間。一旦克服光聲轉換伴隨的生物效應，此系統即成為在三維細胞培養系統中觀測細胞追蹤的有利工具，極具潛力應用於臨床前研究以了解細胞的動態行為。

關鍵字

光聲顯微鏡 ； 三維細胞培養系統 ； 壓縮感知 ； 低秩矩陣填充 ； 細胞追蹤

並列摘要

Observing interactions between T cells and tumor is important for understanding cancer immunotherapy. Optical-resolution photoacoustic microscopy (OR-PAM) can provide not only high spatial resolution but also deeper penetration than conventional optical microscopy, which makes it appropriate for such observations. With appropriate molecular probes, the dual-wavelength OR-PAM can be used to map the distribution of CD8+ cytotoxic T lymphocytes (CTLs) labeled with silica coated gold nanospheres (Si-AuNS) under 523 nm laser irradiation. Likewise, Hepta1-6 tumor spheres can be labelled with indocyanine green (ICG) for 800 nm laser irradiation. Nonetheless, to achieve sufficient spatial sampling for single cells, it takes approximately 20 minutes to scan a volume of 160 × 160 × 150 μm3 at 1 kHz laser PRF. In order to increase the imaging speed for dynamic T cell tracking, we propose a random sparse sampling mechanism to achieve fast sparse photoacoustic data acquisition. With the sparse sampling, the image reconstruction is formulated as low-rank matrix completion based on the compressed sensing (CS) theory. We show that reliable reconstruction can be achieved via nuclear-norm minimization optimization so image quality can be obtained from significantly fewer measurements. Current experimental results reveal that thermal expansion of photoacoustic generation may affect cell viability, which may be a main reason why we have not been able to track cell migration. In conclusion, we use the dual-wavelength OR-PAM with CS to visualize T cell distribution in a 3D tumor microenvironment with higher temporal resolution. Data acquisition time can be reduced by 40% when the sampling density is 0.5. The system can be a valuable tool for evaluating cell tracking in an in vitro 3D cell culture system, once the bioeffects of photoacoustic transformation are overcome. The imaging system is potentially important for preclinical research to understand dynamic cellular behavior.

並列關鍵字

Photoacoustic microscopy ； 3D cell culture systems ； compressed sensing ； low rank matrix completion ； cell tracking

參考文獻

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