Volume 25, Issue 9

We present a method for automated segmentation of the vasculature in retinal images. The method produces segmentations by classifying each image pixel as vessel or nonvessel, based on the pixel's feature vector. Feature vectors are composed of the pixel's intensity and two-dimensional Gabor wavelet transform responses taken at multiple scales. The Gabor wavelet is capable of tuning to specific frequencies, thus allowing noise filtering and vessel enhancement in a single step. We use a Bayesian classifier with class-conditional probability density functions (likelihoods) described as Gaussian mixtures, yielding a fast classification, while being able to model complex decision surfaces. The probability distributions are estimated based on a training set of labeled pixels obtained from manual segmentations. The method's performance is evaluated on publicly available DRIVE (Staal et al.,2004) and STARE (Hoover et al.,2000) databases of manually labeled images. On the DRIVE database, it achieves an area under the receiver operating characteristic curve of 0.9614, being slightly superior than that presented by state-of-the-art approaches. We are making our implementation available as open source MATLAB scripts for researchers interested in implementation details, evaluation, or development of methods

我们提出了一种自动分割视网膜图像中血管网络的方法。该方法通过基于像素的特征向量将每个图像像素分类为血管或非血管，从而生成分割结果。特征向量由像素的强度和多尺度二维Gabor小波变换响应组成。Gabor小波能够调谐到特定频率，从而在单一步骤中实现噪声滤波和血管增强。我们使用贝叶斯分类器，其类条件概率密度函数（似然）描述为高斯混合，能够快速分类，同时能够建模复杂的决策表面。概率分布基于从手动分割获得的标记像素训练集进行估计。该方法在公开可用的DRIVE (Staal et al., 2004) 和 STARE (Hoover et al., 2000) 手动标记图像数据库上进行了性能评估。在DRIVE数据库上，它实现了0.9614的受试者工作特征曲线下面积，略优于现有最先进的方法。我们以开源MATLAB脚本的形式提供我们的实现，供有兴趣的实现细节、评估或方法开发的研究人员使用。

This paper presents an automated method for the segmentation of the vascular network in retinal images. The algorithm starts with the extraction of vessel centerlines, which are used as guidelines for the subsequent vessel filling phase. For this purpose, the outputs of four directional differential operators are processed in order to select connected sets of candidate points to be further classif...

本文提出了一种自动方法用于视网膜图像中血管网络的分割。该算法从提取血管中心线开始，这些中心线作为后续血管填充阶段的指导。为此，处理四个方向微分算子的输出以选择连接的候选点集，以便进一步分类...

Screening programs using retinal photography for the detection of diabetic eye disease are being introduced in the U.K. and elsewhere. Automatic grading of the images is being considered by health boards so that the human grading task is reduced. Microaneurysms (MAs) are the earliest sign of this disease and so are very important for classifying whether images show signs of retinopathy. This paper...

英国及其他地区正在引入使用视网膜摄影检测糖尿病眼病的筛查项目。卫生委员会正在考虑对图像进行自动分级，以减少人工分级的工作量。微动脉瘤是这种疾病的最早征兆，因此对于分类图像是否显示视网膜病变迹象非常重要。本文...

An automated algorithm for tissue segmentation of noisy, low-contrast magnetic resonance (MR) images of the brain is presented. A mixture model composed of a large number of Gaussians is used to represent the brain image. Each tissue is represented by a large number of Gaussian components to capture the complex tissue spatial layout. The intensity of a tissue is considered a global feature and is ...

提出了一种用于噪声、低对比度脑部磁共振（MR）图像组织分割的自动算法。使用由大量高斯分量组成的混合模型来表示脑图像。每个组织由大量高斯分量表示，以捕捉复杂的组织空间布局。组织的强度被视为全局特征，并且...

This paper presents a learning-based method for deformable registration of magnetic resonance (MR) brain images. There are two novelties in the proposed registration method. First, a set of best-scale geometric features are selected for each point in the brain, in order to facilitate correspondence detection during the registration procedure. This is achieved by optimizing an energy function that ...

本文提出了一种基于学习的方法用于磁共振脑图像的变形配准。该方法有两个新颖之处。首先，为了在配准过程中促进对应点检测，为大脑中的每个点选择了一组最佳尺度的几何特征。这是通过优化能量函数来实现的...

Medical images in nuclear medicine are commonly represented in three dimensions as a stack of two-dimensional images that are reconstructed from tomographic projections. Although natural and straightforward, this may not be an optimal visual representation for performing various diagnostic tasks. A method for three-dimensional (3-D) tomographic reconstruction is developed using a point cloud image...

核医学中的医学图像通常表示为从断层投影重建的二维图像堆栈的三维表示。尽管这种表示自然直接，但对于执行各种诊断任务而言，可能并非最佳视觉表示。本文开发了一种使用点云图像进行三维断层重建的方法。

In this paper, we propose and test a new iterative algorithm to simultaneously estimate the nonrigid motion vector fields and the emission images for a complete cardiac cycle in gated cardiac emission tomography. We model the myocardium as an elastic material whose motion does not generate large amounts of strain. As a result, our method is based on minimizing an objective function consisting of t...

本文提出并测试了一种新的迭代算法，用于同时估计门控心脏发射断层扫描中完整心动周期的非刚性运动矢量场和发射图像。我们将心肌建模为弹性材料，其运动不会产生大量应变。因此，我们的方法基于最小化一个由...构成的目标函数。

In this paper, we derive a monotonic penalized-likelihood algorithm for image reconstruction in X-ray fluorescence computed tomography (XFCT) when the attenuation maps at the energies of the fluorescence X-rays are unknown. In XFCT, a sample is irradiated with pencil beams of monochromatic synchrotron radiation that stimulate the emission of fluorescence X-rays from atoms of elements whose K- or L...

本文针对荧光X射线能量未知的情况，推导了一种用于X射线荧光计算机断层成像（XFCT）图像重建的单调惩罚似然算法。在XFCT中，样品被单色同步辐射的笔形束照射，从而激发元素原子（其K或L...）发射荧光X射线。

One of the goals of telemedicine is to enable remote visualization and browsing of medical volumes. There is a need to employ scalable compression schemes and efficient client-server models to obtain interactivity and an enhanced viewing experience. First, we present a scheme that uses JPEG2000 and JPIP (JPEG2000 Interactive Protocol) to transmit data in a multi-resolution and progressive fashion....

远程医疗的目标之一是实现对医学体数据的远程可视化和浏览。需要采用可扩展压缩方案和高效客户端-服务器模型来获得交互性和增强的观看体验。首先，我们提出一种使用JPEG2000和JPIP（JPEG2000交互协议）以多分辨率和渐进方式传输数据的方案...

/sup T/his paper describes a new approach to the automated segmentation of X-ray left ventricular (LV) angiograms, based on active appearance models (AAMs) and dynamic programming. A coupling of shape and texture information between the end-diastolic (ED) and end-systolic (ES) frame was achieved by constructing a multiview AAM. Over-constraining of the model was compensated for by employing dynami...

/sup T/本文描述了一种基于主动外观模型（AAM）和动态规划的X射线左心室（LV）造影自动分割新方法。通过构建多视图AAM，实现了舒张末期（ED）和收缩末期（ES）帧之间形状和纹理信息的耦合。通过采用动态规划来补偿模型的过度约束...

In this paper, we present theoretical developments and experimental results for the problem of estimating the conductivity map inside a volume using electrical impedance tomography (EIT) when the boundary locations of any internal inhomogeneities are known. We describe boundary element method (BEM) implementations of advanced electrode models for the forward problem of EIT. We then use them in the...

本文介绍了在已知内部不均匀性边界位置的情况下，利用电阻抗层析成像（EIT）估计体积内电导率图问题的理论进展和实验结果。我们描述了用于EIT正问题的高级电极模型的边界元方法（BEM）实现。然后，我们将这些方法应用于...

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