磁共振肿瘤矩特征信息研究

目的:采用MR脑肿瘤图像分割与矩方法进行结合,以获取特定器官及组织的轮廓。方法:对MR脑肿瘤图像进行分割,并对分割的结果进行矩描述。通过分析当前常用的医学图像分割方法,采用了一种基于形变模型的医学图像分割方法,并按照相应的理论算法模型和实现步骤对医学图像进行了处理,最后用Visual C 6.0编程,并对MR脑肿瘤图像进行分割实验。结果:从切割的图形中可以看出,本分割方法分割边界清晰,总体不确定性较小,利用矩技术所提取的图像特征在基于内容的图像检索中是有效的。结论:本分割方法切实可行,分割效果较好,为进一步的MR脑肿瘤图像分析和研究提供了一种有效工具。     

PCA和ICA对MRI图像的降维效果分析

本文用PCA-SVM和ICA-SVM以及单个SVM方法对同一MRI实验数据进行降维处理,分析这三种方法在MRI图像上的降维效果。研究发现:PCA-SVM方法适用于大规模实验数组,其判别性能接近于原数组单个SVM模型,并大幅度地减少了运算时间。     

基于PET医学图像边缘检测算法的研究

目的:边缘检测在图像处理中至关重要,可被广泛应用于目标区域识别、区域形状检测、图像分割等图像分析领域。边缘是图像中不平稳现象和不规则结构的重要表现,往往携带着图像中的大量信息,并给出图像轮廓。在医学图像三维显示技术中,为了更精确的临床判别需要得到单像素的清晰轮廓,因此我们提出一种新的边缘检测算法。方法:在传统的小波边缘检测的基础上,提出了一种新的边缘算法,即基于小波极大值边缘检测算法,应用模糊算法构造相应的隶属函数,再对得到的极大值进一步筛选。结果:将该算法应用到医学图像中,最终可以得到较清楚的单像素边缘轮廓,实验结果证明了该算法的可行性。结论:运用这种算法处理过的医学图像边缘锐化更好,更清晰,能够为肿瘤的早期识别提供依据,满足医学影像识别的需要。     

IBM型微机在视觉神经电生理研究中的一个应用

采用IBM-XT微机及其外围硬件Lab Master对一项视觉神经电生理实验施行实时的数据采集、处理和控制。其中:Lab Master中的D/A和8255型并行接口输出模拟量和数字量,控制一台图像发生器,产生不同的视觉图像刺激;用LabMaster中的计数器,计数一定时间内神经脉冲的个数,然后进行数据处理。     

牙形石数字图像采集与图像增强方法研究

化石自动鉴定研究是古生物学研究的一个前沿方向。数字图像的采集与处理是化石自动鉴定的基础,处理后的图像质量直接影响了计算机识别的效果。文中以牙形石为例,通过对化石数字图像采集方法的研究,获得了光学显微图像和扫描图像两类牙形石数字图像。详细介绍了灰度变换、均值滤波、中值滤波和微分算子等图像增强方法,通过实验比较了各自的优缺点。实验结果表明,这些方法可以有效改善牙形石数字图像质量。选择合适的图像增强方法能够突出牙形石的细节,有利于牙形石的特征观察和进一步的分析,为后续的牙形石自动鉴定研究奠定了基础。     

微柱凝胶卡血清实验图像识别的研究

根据微柱凝胶卡血清实验后图像的特征,采用VB语言编程,对采集到的图片进行数字化处理,通过设置不同像素二值化阈值,以确定单个微柱试管中心线、及实验结果阴阳性判别,最后得出整张微柱凝胶卡血清实验结果。实例证明识别程序的正确性和实用性。     

一种简便生物学实验教学显微图像分析系统构建

采用数码相机及目镜测微尺获取实验结果图像，并结合图像软件Photoshop构建简便显微图像分析系统，解决在生物学实验教学实践中涉及到的计数、面积计算及大小测量相关分析。实验数据结果表明该系统简单、便捷、实用、准确。在生物学实验教学及科学研究实验中具有很好的推广与应用价值。     

基于图像处理的血液细胞特征提取

利用数学形态学知识和图像处理方法,对缺铁性贫血的血液显微图像进行了分析,编制了相应的计算程序,对选取的区域内细胞的个数、半径和面积等重要参数进行了统计和处理,这对进一步研究细胞及其组织变化、医学临床诊断等问题,具有一定的指导意义。     

基于小波分析的医学图像的处理

医学图像的好坏直接影响着医生对病情的诊断和治疗,因此利用数字图像处理等技术对医学图像进行有效的处理,已成为医学图像处理研究和开发的一大热点.小波分析是对傅立叶变换的继承和发展,在医学影像领域有着广阔的应用前景.介绍了二维离散小波变换的一般形式,在图像分解的基础上,利用小波分析对医学图像进行去噪和增强处理,能够有效的改善图像质量,有利于医生对病情的诊断和治疗.     

基于Gabor滤波器的皮肤纹理图像增强

在疗效化妆品中,常常需要对护肤品的性能和效果进行分析。皮肤纹理的检测是客观衡量疗效化妆品的有效手段。基于计算机视觉技术的皮肤纹理分析,对拍摄的皮肤图像要进行图像预处理,增强图像,为后续的分析提供有效的数据。采用经过微调的定向的Gabor滤波器进行增强图像,通过实验得出Gabor滤波器不仅抑制噪声的效果好,还保留了皮肤图像的整体和局部特征。     

Stylized chromosome images

Stylized chromosome images 1) serve as a format to test effects of preprocessing algorithms used in automated karyotyping; 2) enhance the ability of humans to perform quantitative analysis of chromosomal aberrations; 3) provide an alternative format for karyotype hard copies produced by automated systems. Stylized chromosomes are two-dimensional computer-generated images based on information extracted from one-dimensional width and density profiles. These profiles correspond to what cytogeneticists observe through the microscope as the shape and banding patterns of stained chromosomes. Stylized presentation sharpens chromosome band boundaries and perimeters, reduces "noise," and enhances gray level variations, which are difficult to distinguish by humans on photographic or computer generated karyotypes. Karyotyping accuracy using stylized images was used to detect difficult areas for automated chromosome identification. Landmark bands sufficient to classify chromosomes were identified; shapes of chromosomes reflected in width profiles were said to aid classification. A two-step automated karyotyping strategy proposed is: 1) classify chromosomes by landmarks, minimum information needed for identification; 2) subsequently employ the full banding pattern with maximum resolution to detect aberrations. Stylized images of abnormal chromosomes have potential for testing hypothesis regarding breakpoints and quantitative analysis, but improvements are needed in homologue normalization and definition of termini of chromosomes.     

IMACULAT — An Open Access Package for the Quantitative Analysis of Chromosome Localization in the Nucleus

The alteration in the location of the chromosomes within the nucleus upon action of internal or external stimuli has been implicated in altering genome function. The effect of stimuli at a whole genome level is studied by using two-dimensional fluorescence in situ hybridization (FISH) to delineate whole chromosome territories within a cell nucleus, followed by a quantitative analysis of the spatial distribution of the chromosome. However, to the best of our knowledge, open access software capable of quantifying spatial distribution of whole chromosomes within cell nucleus is not available. In the current work, we present a software package that computes localization of whole chromosomes - Image Analysis of Chromosomes for computing localization (IMACULAT). We partition the nucleus into concentric elliptical compartments of equal area and the variance in the quantity of any chromosome in these shells is used to determine its localization in the nucleus. The images are pre-processed to remove the smudges outside the cell boundary. Automation allows high throughput analysis for deriving statistics. Proliferating normal human dermal fibroblasts were subjected to standard a two-dimensional FISH to delineate territories for all human chromosomes. Approximately 100 images from each chromosome were analyzed using IMACULAT. The analysis corroborated that these chromosome territories have non-random gene density based organization within the interphase nuclei of human fibroblasts. The ImageMagick Perl API has been used for pre-processing the images. The source code is made available at www.sanchak.com/imaculat.html.     

The DNA-based human karyotype

Image cytometry and computer analysis are used to determine the relative DNA content and the DNA-based centromeric index of the 24 chromosomes of the human karyotype. A two-step procedure is used. Chromosomes of cells in metaphase first are stained with quinacrine and identified visually by their fluorescent Q-band patterns. They then are stained for DNA using gallocyanin-chrome alum. The chromosome images are scanned and recorded as digital values of optical density by an CYDAC image cytometric microscope system, CYDAC. The digital images are processed by computer to measure for each chromosome the relative DNA stain contents of the whole chromosome and of the p and q arms and the DNA-based centromeric index. About ten cells are analyzed for each of the donors, who are phenotypically normal men and women. The chromosome measurements are pooled by chromosome type for each donor and are compared among donors. The means of the chromosome measurements give the DNA-based human karyotype. Analysis of the DNA-based data shows that some chromosomes or portions of chromosomes vary significantly among donors. These variants do not correlate with detectable morphologic polymorphisms, such as Q- or C-band variants; thus they represent new and otherwise undetectable chromosome polymorphisms whose genetic basis and clinical significance are yet to be determined.     

Quantitative motion analysis of subchromosomal foci in living cells using four-dimensional microscopy

The motion of subchromosomal foci and of whole chromosome territories in live human cell nuclei was investigated in four-dimensional space-time images. Visualization of subchromosomal foci was achieved by incorporating Cy3-dUTP into the nuclear DNA of two different cell types after microinjection. A subsequent segregation of the labeled cell nuclei led to the presence of only a few labeled chromosome territories on a background of nonlabeled chromatin (. Hum. Genet. 102:241-251). This procedure yielded many distinct signals in a given cell nucleus. Motion analysis in four-dimensional space-time images was performed using single-particle tracking and a statistical approach to the detection of a possible directional motion of foci relative to the center of mass of a chromosome territory. The accuracy of the analysis was tested using simulated data sets that closely mirrored the experimental setup and using microparticles of known size. Application of the analysis tools to experimental data showed that mutual diffusion-like movements between foci located on different chromosomes were more pronounced than inside the territories. In the time range observed, movements of individual foci could best be described by a random diffusion process. The statistical test for joint directed motion of several foci inside chromosome territories revealed that foci occasionally switched from random to directional motion inside the territories.     

Pixel sensible local band analysis in microscopic chromosome images using CSPA

In chromosome analysis, local band analysis plays the main role to identify the perfect matched chromosome in metaspread images to attain the karyotyping. Literature investigations are narrow in chromosome image band analysis due to the higher complexities. In this paper, Pixel level based Conditional Seed Point Algorithm (CSPA) is proposed. This simulation algorithm separates the weak band region to the strong band region, and the strong band region area evaluated was based on the Region of Seed condition Points. This algorithm works well for different intensity levels and adopts the structural changes to identify the bands in image. This algorithm was simulated in more than 450 individual chromosomes to identify the local bands in the chromosome images and provided the accuracy more than 96%.     

Simultaneous detection of near-field topographic and fluorescence images of human chromosomes via scanning near-field optical/atomic-force microscopy (SNOAM).

Scanning near-field optical/atomic-force microscopy (SNOAM) provided us with simultaneous topographical and optical images of human chromosomes using a sharp and bent optical fiber as a near-field optical probe. Native chromosomes were spread out onto a coverslip using the surface-spreading whole-mount method. The SNOAM system does not need pretreatment of samples such as metal coating or chemical immobilization. Near-field topographic and fluorescence images provided useful information on native chromosome structure.     

QUANTITATIVE TRITIUM AUTORADIOGRAPHY OF MAMMALIAN CHROMOSOMES : I. The Basic Method

A technique has been developed that allows repeated autoradiographs to be made of the isotope distribution in the chromosomes of a single cell. A series of 10 separate autoradiographs were made of a Chinese hamster diploid male metaphase cell which had been labeled with tritiated thymidine during the first 15 minutes of its DNA synthesis period in the previous interphase. Each autoradiograph had low grain densities above the chromosomes so that quantitation was feasible. The separate autoradiographs were photographically combined into a single composite in which grain images were converted to lines oriented at right angles to the chromosome axis. The line densities were then measured with a recording microdensitometer to yield graphs reflecting the isotope distribution along each chromosome. The area under each graph was directly proportional to the total number of grains counted above the corresponding chromosome in the 10 separate autoradiographs. The distribution of isotope along the chromosomes was different for each chromosome, and in some cases homologs also differed in their early labeling patterns.     

Quantitative microscopy after fluorescence in situ hybridization - a comparison between repeat-depleted and non-depleted DNA probes

Complex probes used in fluorescence in situ hybridization (FISH) usually contain repetitive DNA sequences. For chromosome painting, in situ suppression of these repetitive DNA sequences has been well established. Standard painting protocols require large amounts of an unlabeled 'blocking agent', for instance Cot-1 DNA. Recently, it has become possible to remove repetitive DNA sequences from library probes by means of magnetic purification and affinity PCR. Such a 'repeat depleted library probe' was hybridized to the q-arm of chromosome 15 of human metaphase spreads and interphase cell nuclei without any preannealing by Cot-1 DNA. Apart from this, 'standard' FISH conditions were used. After in situ hybridization, microscope images were obtained comparable to those achieved with the #15q library probe prior to depletion. The images were recorded by a true color CCD camera. By digital image analysis using 'line scan' and 'area scan' procedures, the painting efficiency expressed in terms of relative fluorescence signal intensity was quantitatively evaluated. The painting efficiency using the repeat depleted probe of chromosome 15q was compared to the painting efficiency after standard FISH. The results indicate that both types of probes are compatible to a high FISH efficiency. Using equivalent probe concentrations, no significant differences were found for FISH with standard painting probes and repeat depleted painting probes.     

Selective cleaning of the cell debris in human chromosome preparations studied by scanning force microscopy

The chromosome structure is one of most challenging biological structures to be discovered. Most evidence about the structure comes from optical microscopy. Scanning force microscopy (SFM) can achieve molecular resolution and allows imaging in liquids. However, little information about the chromosome structure has been revealed by SFM. In this work, a mild enzymatic treatment is applied to the chromosomes to remove selectively the RNA and proteins coming from the cell. The resulting SFM images indicate that a protein film with embedded RNA molecules covers chromosomes in standard cytogenetic preparations. The thickness of the protein layer is 15-35 nm and the RNA adheres preferentially to the chromosome surface. The cell material film results in a quite smooth chromosome surface without evidence of any structural detail. After treatment, the chromosome was cleaned from cell residues and individual chromatin fibers at the surface were resolved. Furthermore, insights about the higher order structure of the chromosome can be inferred.     

Algorithms for finding most dissimilar images with possible applications to chromosome classification

By using chromosome images as a framework, algorithms for finding most dissimilar images are presented and illustrated by examples. In terms of angles, a chromosome image consists of two exterior biangles and two interior biangles. Biangles are defined and classified into 180° biangles, >180° biangles and <180° biangles. The dissimilarity of biangles and its geometric interpretation together with various properties of biangles are also presented. The results may have useful applications in pattern recognition, scene analysis, information storage and retrieval, artificial intelligence and fuzzy set theory.