Applications of Photon Migration to Tissue Tomography and Spectroscopy

我们继续在非侵入性定量光学成像和光谱学的光-组织相互作用的理论、实验和计算方面的工作。柏林PTB的研究人员为我们提供了两个波长（670和780nm）的乳房图像的透照几何飞行时间测量。我们已经应用了我们的方法，即时间相关对比函数，来量化正常组织背景的大小和光学特性，以及那些通过标准乳房x光检查定位的肿瘤。我们成功地找到了肿瘤的确切位置，估计了肿瘤的大小，并获得了肿瘤和背景的散射和吸收系数。利用氧和脱氧血红蛋白的吸收光谱，我们可以从670和780nm处的吸收系数估计出肿瘤和背景组织的氧饱和度和总血容量。研究边界对图像影响的工作正在进行中。为了避免在口腔中进行切口活检，已经建立了一种理论框架来量化口腔粘膜上皮层的无创增厚。我们已经开发了一种使用斜角反射设置的光谱装置，并开始用于II期临床试验（由NCI设计），用于炎症和化学预防药物效果的非侵入性研究。将白斑患者的结果与正常受试者的结果进行比较，定性地证明了该理论的预测。筛查更多患者并使测量更加量化的工作正在进行中。我们正在寻求使用外源性和内源性荧光标记，以便能够实现所研究的组织异常的光谱特征的特异性。在与特拉维夫大学的合作中，我们获得了BSF的资助，继续研究我们之前开发的3D重建算法的实际实施，该算法可以定位荧光团的位置和浓度。我们的逆算法将用于寻找充满荧光颗粒的脂质体的位置和浓度，作为体内定位荧光团块的模型。沿着这些研究路线，我们正在测试光子迁移的分析理论，通过使用幻影实验来检索生物分析物的寿命。我们正在继续与NCI的研究人员合作，研究我们的光子迁移理论在开发一种引导活检红外荧光成像系统中的实际应用，该系统用于使用荧光颗粒检测乳腺癌前哨淋巴结。

We have continued our work on theoretical, experimental, and computational aspects of light -tissue interactions for non-invasive quantitative optical imaging and spectroscopy. Researchers at PTB of Berlin provided us time of flight measurements in transillumination geometry of breast images in two wavelengths (670 and 780nm). We have applied our methodology known as time-dependent contrast functions, to quantify the size and the optical properties of the normal tissue background and those of the tumor localized by standard mammography. We were successfully able to find the exact location, estimate the size, and retrieve the scattering and the absorption coefficients of the tumor and those of the background. Using the absorption spectra of oxy- and deoxy-hemoglobin, we were able to estimate the oxygen saturation and the total blood volume of the tumor and background tissue from the absorption coefficients at 670 and 780nm. Work is underway to study the effects of boundaries on the images. In order to avoid incisional biopsy in the oral cavity, a theoretical framework has been developed to quantify the thickening of the epithelial layer in oral mucosa non-invasively. We have developed a spectroscopic device which uses an oblique angle reflectance setting and started to be used in a Phase II clinical trial (designed by NCI) for the non-invasive study of inflammation and effects of chemopreventative drugs. The results from a patient with leukoplakia compared to that obtained from a normal subject show qualitatively the prediction of the theory. Work is underway to screen more patients and make the measurement more quantitative.We are pursuing the use of exogenous and endogenous fluorescent markers to be able to achieve specificity of the spectroscopic signatures of the tissue abnormality under investigation. In collaboration with the University of Tel-Aviv, we have been awarded a BSF grant to continue our research on practical implementation of our previously developed 3D reconstruction algorithm which localizes the position and the concentration of fluorophore masses. Our inverse algorithm will be used to find the position and the concentration of liposomes filled with fluorescent particles as a model for localized fluorescent masses in vivo.. Along these line of research, we are testing an analytical theory of photon migration to retrieve the life-time of biological analytes by using phantom experiments. We are continuing a collaboration with researchers at NCI to study the practical use of our photon migration theory in the development of a guided biopsy infrared fluorescence imaging system for sentinel node detection in breast cancer using fluorescent particles.