Determination of epithelial tissue scattering coefficient using confocal microscopy

Most models of light propagation through tissue assume the scattering properties of the various tissue layers are the same. The authors present evidence that the scattering coefficient of normal cervical epithelium is significantly lower than values previously reported for bulk epithelial tissue. They estimated the scattering coefficient of normal and precancerous cervical epithelium using measurements of the reflectance as a function of depth from confocal images. Reflectance measurements were taken from ex vivo cervical biopsies and fit to an exponential function based upon Beer's law attenuation. The mean scattering coefficients derived were 22 cm/sup -1/ for normal tissue and 69 cm/sup -1/ for precancerous tissue. These values are significantly lower than previously reported for bulk epithelial tissues and suggest that scattering of bulk tissue is dominated by the stroma. They also suggest that computational models to describe light propagation in epithelial tissue must incorporate different scattering coefficients for the epithelium and stroma. Further, the lower scattering of the epithelium suggests greater probing depths for fiber optic probes used by optical diagnostic devices which measure reflectance and fluorescence in epithelial tissue. The difference in scattering between normal and precancerous tissue is attributed to increased nuclear size, optical density, and chromatin texture. The scattering coefficients measured here are consistent with predictions of numerical solutions to Maxwell's equations for epithelial cell scattering.     

Endoscopic OCT Approaches Toward Cancer Diagnosis

A majority of human cancers originate in the epithelial tissues of the body. These include cancers in the oral cavity and pharynx, the digestive system, the respiratory system, the genital system, and the urinary system. It has been shown that early detection of these cancers can significantly improve the prognosis of affected patients. These cancers are currently diagnosed using endoscopic methods during which video imaging systems are inserted to visualize the tissue surface and guide tissue biopsies. Endoscopic optical coherence tomography (EOCT) has the potential to improve the early detection of epithelial cancers by providing high resolution, subsurface images of epithelial tissues. These subsurface images can assist the surgeon in selecting biopsy locations, and may also provide diagnostic information including the presence of cancerous and precancerous conditions in these tissues. This paper reviews current EOCT approaches toward imaging and evaluating internal epithelial tissues for various pathologies.     

Polarized light scattering spectroscopy for quantitativemeasurement of epithelial cellular structures in situ

We report an in situ method of probing the structure of living epithelial cells, based on light scattering spectroscopy with polarized light. The method makes it possible to distinguish between single backscattering from uppermost epithelial cells and multiply scattered light. The spectrum of the single backscattering component can be further analyzed to provide histological information about the epithelial cells such as the size distribution of the cell nuclei and their refractive index. These are valuable quantities' to detect and diagnose precancerous changes in human tissues     

Coherent methods in confocal microscopy

The authors review the use of 2 kinds of coherent imaging methods in confocal microscopy: interferometry and the use of optical fibres. In both cases, the emphasis is concerned with detecting both the confocal field amplitude and its phase. It is usual in confocal systems to detect only the image intensity and so to loose all phase information. In order to detect the phase with an incoherent photodetector, it is necessary to use some form of interferometry. In the classical interferometer, the authors show that by detecting the phase and amplitude in a conventional interference microscope employing a large area detector it is possible to obtain confocal imaging. Indeed, the interference term images in conventional and confocal interference microscopes are found to be identical. An optical fibre-based confocal interference microscope is shown to have some practical advantages over a conventional, noncommon path implementation. The question of resolution in phase imaging is discussed and it is shown that due to the inherent nonlinearity of the process, great care should be taken in interpreting these images. The introduction of optical fibres instead of pinholes is shown to lead to simplification in system design. However, the introduction of 2-mode fibres makes the system more versatile. In essence, the fundamental mode detects the image amplitude and the first order mode detects the differential of the image amplitude. These modes then propagate along the fibre with different speeds and, hence, emerge from the fibre with a relative phase difference determined by the length of the fibre. These 2 modes are finally allowed to interfere. In this way, it is possible to obtain both confocal differential amplitude contrast, and differential phase contrast images simultaneously, without any other alteration to the optical system     

Accurate measurement of total attenuation coefficient of thin tissue with optical coherence tomography

Noninvasive accurate measurements of tissue optical properties are needed for many diagnostic and therapeutic applications. Optical coherence tomography (OCT) recently proposed for high-resolution imaging in tissue can potentially be applied for accurate, noninvasive, and high-resolution measurement of tissue total attenuation coefficient. However, confocal function (dependence of OCT sensitivity on the distance of probed site from the focal plane of the objective lens) and multiple scattering substantially limit the accuracy of the measurement with the OCT technique. We studied the influence of the confocal function and multiple scattering on the accuracy of the measurement and proposed methods that provide measurement of the total attenuation coefficient with a significantly reduced systematic error. Experiments were performed in tissue phantoms and porcine and human skin in vitro and in vivo. Our data indicate that the tissue total attenuation coefficient can noninvasively be measured in vivo with the accuracy of 5%-10% in the range from 0.5 to 17 mm/sup -1/ and about 20% in the range up to 40 mm/sup -1/. These results suggest that the proper correction of the OCT-based measurement for the confocal function and multiple scattering provides absolute values of tissue total attenuation coefficient with high accuracy and resolution that may not be achievable by other optical techniques in vivo.     

MEMS-Based Dual Axes Confocal Microendoscopy

We demonstrate a miniature, near-infrared microscope (λ = 785 nm) that uses a novel dual axes confocal architecture. Scalability is achieved with post-objective scanning, and a MEMS mirror provides real time (>4 Hz) in vivo imaging. This instrument can achieve sub-cellular resolution with deep tissue penetration and large field of view. An endoscope-compatible version can image digestive tract epithelium to guide tissue biopsy and monitor therapy.     

Spectral polarization imaging of human rectum-membrane-prostate tissues

Human rectum-membrane-prostate tissue samples were studied using a near-infrared spectral polarization imaging technique to detect small objects and structural changes inside prostate tissues through the rectum. Four modeling samples were made with a small piece of absorber or prostate tissue dyed with a contrast agent (indocyanine green) embedded inside a large piece of prostate tissue in rectum-membrane-prostate structures. The depth of the foreign objects underneath the surface of the rectum-membrane-prostate structures was varied from a millimeter to a centimeter to obtain the critical imaging distance. Different spectral polarization imaging methods with and without contrast agents were performed and compared. The results show that small objects hidden inside the host prostate tissues in the rectum-membrane-prostate structures at depths of 2.5, 4.0, and 7.5 mm can be imaged and identified using the scattering light imaging, tissue emission wing imaging, and contrast agent fluorescence imaging methods, respectively. Our results indicate the potential of imaging and detecting structural changes and cancers inside prostate tissue though rectum-membrane-prostate tissues using this noninvasive spectral polarization imaging technique.     

Advances in oral cancer detection using optical coherence tomography

Optical coherence tomography (OCT) is a new modality capable of cross sectional imaging of biological tissue. Due to its many technical advantages such as high image resolution, fast acquisition time, and noninvasive capabilities, OCT is potentially useful in various medical applications. Because OCT systems can function with a fiber optic probe, they are applicable to almost any anatomic structures accessible either directly, or by endoscopy. OCT has the potential to provide a fast and noninvasive means for early clinical detection, diagnosis, screening, and monitoring of precancer and cancer. With an imaging depth range of 2-3 mm, OCT diagnostics are particularly suitable for the oral mucosa. Currently, it is difficult to detect premalignant and malignant oral lesions due to their often multifocal nature and need for repeated biopsies. The goal of this study was to evaluate the feasibility of OCT for the diagnosis of multiple stages of oral cancer progression. In this paper, we present not only conventional 2-D OCT images, but also 3-D volume images of normal and precancerous lesions. Our results demonstrate that OCT is a potential tool for cancer detection with comprehensive diagnostic images.     

A high-resolution MACROscope with differential phase contrast, transmitted light, confocal fluorescence, and hyperspectral capabilities for large-area tissue imaging

Recent advances in imaging technology have contributed greatly to biological science. Confocal fluorescence microscopes can acquire two-dimensional and three-dimensional images of biological samples such as live or fixed cells and tissues. Specimens that are large (e.g., a 10 mm/spl times/10 mm tissue section) and overfill the field of view (FOV) of typical microscope objectives require the use of image tiling to cover the entire specimen. This can be time consuming and cause artifacts in the composite image. The MACROscope system (Biomedical Photometrics Inc., Waterloo, ON, Canada) is a confocal device with a 22 mm/spl times/70 mm FOV designed for imaging large tissue sections in a single frame. The prototype demonstrated here can obtain images in reflected, transmitted, fluorescence, phase contrast, and hyperspectral modes. The new spectral imaging mode is characterized with a series of test targets, and sampled spectra are compared to a commercial spectrometer. Fluorescence images of human SiHa tumor xenografts stained with CD31-Cy3, showing blood vessel location, and EF5-Cy5, showing areas of tissue hypoxia, were collected. Differential phase contrast images of the same section, as well as human epithelial cells, were recorded to assess the phase contrast mode. Additionally, fluorescence images of Cytokeratin-Cy3 stained squamous cell carcinoma tissue sections were captured. Finally, red, green, blue transmitted light images of human tongue were obtained. This new device avoids the need for image tiling and provides simultaneous imaging of multiple fluorescently labeled tissue-specific markers in large biological samples. This enables time- and cost-efficient imaging of (immuno)histopathological samples. This device may also serve in the imaging of high-throughput DNA and tissue arrays.     

基于LabVIEW探测装置地速和偏流角指示器模拟器设计

利用虚拟仪器软件开发平台LabVIEW，实现了对探测装置地速和偏流角指示器的模拟，使整个探测装置进行测试时，既可以防止其它故障部件对指示器的损坏，又可以使维修人员直观的进行操作，同时可以进行更准确的故障诊断。     

基于双路特征的宫颈细胞核分割

宫颈细胞核的分割问题研究对宫颈癌筛查诊断具有重要意义，但受边缘模糊及存在干扰物影响给分割任务带来了巨大挑战。针对此问题提出一种基于DeepLabV3+网络的细胞核分割方法，首先充分利用主干网络的输出进行多尺度特征融合，并引入注意力机制，构建了细胞团分割模型，以减少背景中干扰物对细胞核分割的影响；基于此设计了融合Transformer与ResNet50的双路特征提取模块，兼顾模型对全局信息的获取及低层上下文特征的敏感度，提高了模型对细胞核与干扰信息的辨别能力。实验结果表明，算法在宫颈细胞核的分割任务中取得了良好的分割效果，均交并比为0.832 9,较DeepLabV3+模型提高了2.33%,且与其他方法相比获得了更优的性能指标。     

杂背景下TFT-LCD表面缺陷检测系统的设计

设计了背景去除算法和缺陷区域检测算法,对复杂背景与低对比度条件下采集的TFT-LCD图像进行处理,利用一维傅里叶变换和全尺寸小波变换提取缺陷特征信息,可以较准确地检测出缺陷区域.搭建了在线检测系统平台,通过辅助光源和高速线阵相机采集图像,由图像采集卡保存至计算机中,利用Matlab编写上层图像处理软件进行在线检测.实验...     

In Vivo Molecular Imaging of Cervical Neoplasia Using Acetic Acid as Biomarker

In this paper, a molecular imaging method employing acetic acid dilute solution as a biomarker is described. An interpretation of the biophysical processes that are involved in the biomarker-tissue interaction and are determining the in vivo measured dynamic scattering characteristics is presented. On the basis of this interpretation, a compartmental model of the epithelium is developed for predicting the epithelial transport phenomena that are expected to be correlated with the dynamic characteristics of the backscattered light. The model predictions have been compared with the experimental data obtained from patients with cervical neoplasia of different grade, with the aid of a specially developed imaging system. Comparisons confirmed the validity of the interpretation of the phenomenon, and particularly, the fact that dynamic scattering characteristics are largely determined by the intracellular proton concentration kinetics. In addition, the correlation of the latter with both structural and functional alterations, associated with cervical neoplasia development, has been predicted theoretically and confirmed experimentally. The established correlation enables the derivation of quantitative indices expressing disease-specific microstructural and functional alterations, from the in vivo measured dynamic optical characteristics. This highlights the potential of the developed imaging method and technology for the noninvasive diagnosis, guided therapeutics, and screening of cervical neoplasia.     

基于时间差法的共焦测头算法改进

近年来,三坐标测量机正在迅速发展。测头作为三坐标测量机的基本部件之一,与测量机的功能、工作效率、精度密切相关。光学非接触测头具有测量精度高,没有测量力,没有摩擦,测量速度与采样频率高等特点,是目前研究比较活跃的领域。本文中所讲到的共焦测头就是光学非接触测头的一种。本文在研究了共焦法测量传感器及其测量系统的基础上,提出了一种通过测量连续两个峰值信号的时间差来计算被测表面位置的方法。这种测头舍弃了参考信号,简化了系统结构,降低了成本,实用性更强。     

结合MSRCR与多尺度融合的水下图像增强算法

为解决水下图像增强时出现的图像边缘细节模糊,亮度不均等问题,提出了一种结合带色彩恢复的多尺度视网膜增强算法(MSRCR)与多尺度融合的水下图像增强算法.首先,将获取到的水下图像基于的MSRCR算法色彩校正,并将校正后的图像转换到Lab颜色空间对亮度分量进行自适应增强.其次,对MSRCR色彩校正图像和Lab空间亮度分量增...     

局部放电数字化在线检测诊断系统

局部放电（PD）是导致高压电工设备绝缘击穿的主要原因。局部放电 在线检测是保证电力设备可靠运行的有效手段。本文以西安交通大学绝缘国家重点实验室研制的一套数字化局部放电在线检测诊断系统为例,在高压屏蔽室内对典型试样的放电进行采集,并绘制其放电谱图,进行指纹识别、放电模式识别分析。     

In Vivo Cell Tracking With Video Rate Multimodality Laser Scanning Microscopy

Studies of biological processes, such as disease progression and response to therapy, call for live imaging methods that allow continuous observation without terminating the study subject for histological tissue processing. Among all current imaging modalities, optical microscopy is the only method capable of probing live tissue with cellular and subcellular resolution. We present a video-rate (30 frames/s), multimodality imaging system that is designed specifically for live animal imaging and cell tracking. In vivo depth-sectioned, high-resolution images are obtained using confocal and nonlinear optical techniques that extract structural, functional, and molecular information by combining multiple contrast mechanisms, including back scattering, fluorescence (from single- and two-photon excitation), second harmonic generation, and coherent anti-Stokes Raman scattering. Simultaneous use of up to three modalities is possible and eliminates the need for coregistration, especially on large-scale images. A real-time movement correction algorithm was developed to extend integration times in cases where the image needs to be stabilized against subject movement. Finally, imaging of fast moving leukocytes in blood vessels is made possible with a modification that permits operation at 120 frames/s over a smaller area. Sample imagery obtained in vivo with the microscope is presented to illustrate the capabilities.     

Review and Recent Development of Angle-Resolved Low-Coherence Interferometry for Detection of Precancerous Cells in Human Esophageal Epithelium

The combination of low-coherence interferometry with angle-resolved light scattering measurements has been shown to be a powerful method for determining the structure of cell nuclei within intact tissue samples. The nuclear morphology data have been used as a biomarker of neoplastic change in a wide range of settings. Here, we review the development of angle-resolved low-coherence interferometry (a/LCI) for assessing the health status of human esophageal epithelial tissues based on depth-resolved measurements of the morphology of cell nuclei. The design and implementation of clinical instrumentation are reviewed, and results from ex vivo human tissue measurements are presented to validate the capabilities of the technique. In addition to the review of earlier papers, new results are presented, which demonstrate the first application of a portable a/LCI system with a flexible endoscopic probe to assessing depth-resolved nuclear morphology in a clinical setting. High sensitivity for the detection of precancerous tissues is demonstrated.     

极坐标图像法用于检测变压器绕组的微小辐向变形故障

频率响应分析法一直以来被认为是诊断电力变压器绕组变形故障最具潜力的方式,然而,现有频率响应分析法大多仅利用频率响应的幅值信息,而忽略了其相位变化的特性,针对某些故障类型,例如绕组的微小辐向变形故障,仅利用幅值信息的方法,故障诊断的灵敏度并不高。因此,文中提出一种新的极坐标图像法,利用频率响应构造极坐标图像,进而辅助诊断绕组变形故障。通过开展绕组等效电路模型的算例分析,结论证实在传统频率响应分析法不能反映绕组微小辐向变形故障时,此提出的方法可能更有效地检测出绕组故障,极坐标图像法具有更高的诊断灵敏度。