Volume 27, Issue 1

Optic disc (OD) detection is a main step while developing automated screening systems for diabetic retinopathy. We present in this paper a method to automatically detect the position of the OD in digital retinal fundus images. The method starts by normalizing luminosity and contrast through out the image using illumination equalization and adaptive histogram equalization methods respectively. The OD detection algorithm is based on matching the expected directional pattern of the retinal blood vessels. Hence, a simple matched filter is proposed to roughly match the direction of the vessels at the OD vicinity. The retinal vessels are segmented using a simple and standard 2-D Gaussian matched filter. Consequently, a vessels direction map of the segmented retinal vessels is obtained using the same segmentation algorithm. The segmented vessels are then thinned, and filtered using local intensity, to represent finally the OD-center candidates. The difference between the proposed matched filter resized into four different sizes, and the vessels' directions at the surrounding area of each of the OD-center candidates is measured. The minimum difference provides an estimate of the OD-center coordinates. The proposed method was evaluated using a subset of the STARE project's dataset, containing 81 fundus images of both normal and diseased retinas, and initially used by literature OD detection methods. The OD-center was detected correctly in 80 out of the 81 images (98.77%). In addition, the OD-center was detected correctly in all of the 40 images (100%) using the publicly available DRIVE dataset.

视盘检测是开发糖尿病视网膜病变自动筛查系统的主要步骤。本文提出了一种自动检测数字视网膜眼底图像中视盘位置的方法。该方法首先通过光照均衡化和自适应直方图均衡化分别对图像进行亮度和对比度归一化。视盘检测算法基于匹配视网膜血管的预期方向模式。因此，提出了一种简单的匹配滤波器来粗略匹配视盘附近血管的方向。使用简单且标准的二维高斯匹配滤波器对视网膜血管进行分割。随后，使用相同的分割算法获得分割后的视网膜血管的方向图。然后对分割后的血管进行细化，并使用局部强度进行滤波，最终得到视盘中心候选点。测量所提出的匹配滤波器（调整成四种不同尺寸）与每个视盘中心候选点周围区域的血管方向之间的差异。最小差异提供了视盘中心坐标的估计。使用STARE项目数据集的一个子集对所提出的方法进行了评估，该子集包含81张正常和病变视网膜的眼底图像，并且最初被文献中的视盘检测方法使用。在81张图像中，有80张（98.77%）正确检测到了视盘中心。此外，使用公开可用的DRIVE数据集，在40张图像中全部（100%）正确检测到了视盘中心。

This paper provides a comprehensive and quantitative review of spatial transformations models for nonrigid image registration. It explains the theoretical foundation of the models and classifies them according to this basis. This results in two categories, physically based models described by partial differential equations of continuum mechanics (e.g., linear elasticity and fluid flow) and basis f...

本文对非刚性图像配准的空间变换模型进行了全面且定量的综述。它解释了模型的理论基础，并据此进行分类。结果分为两类：基于物理的模型（由连续力学的偏微分方程描述，如线弹性和流体流动）和基...

This paper investigates the performance of a new multivariate method for tensor-based morphometry (TBM). Statistics on Riemannian manifolds are developed that exploit the full information in deformation tensor fields. In TBM, multiple brain images are warped to a common neuroanatomical template via 3-D nonlinear registration; the resulting deformation fields are analyzed statistically to identify ...

本文研究了一种新的张量形态测量学(TBM)多变量方法的性能。开发了基于黎曼流形的统计方法，充分利用了形变张量场中的全信息。在TBM中，通过三维非线性配准将多个脑图像扭曲到共同的神经解剖模板上；对生成的形变场进行统计分析以识别...

A novel magnetic resonance (MR)-tracking method specifically developed to locate the ferromagnetic core of an untethered microdevice, microrobot, or nanorobot for navigation or closed-loop control purpose is described. The tracking method relies on the application of radio-frequency (RF) excitation signals tuned to the equipotential magnetic curves generated by the magnetic signature of the object...

描述了一种新颖的磁共振追踪方法，专门用于定位无系留微器件、微型机器人或纳米机器人的铁磁核心，以实现导航或闭环控制目的。该方法依赖于将射频激励信号调谐到由物体的磁特征产生的等势磁曲线上。

Endoscopic capsule is a recent medical technology with important clinical benefits but suffering from a practical handicap: long exam annotation times. This paper proposes and compares two approaches (Bayesian and support vector machines) that can be used to segment the gastrointestinal tract into its four major topographic areas, allowing the automatic estimation of the clinically relevant gastri...

内镜胶囊是一种近期出现的医疗技术，具有重要的临床益处，但存在一个实际障碍：检查注释时间长。本文提出并比较了两种方法（贝叶斯和支持向量机），可对胃肠道进行四个主要地形区域的自动分割，从而实现临床相关胃...的自动估计。

The technology of multislice X-ray computed tomography (MSCT) provides volume data sets with approximately isotropic resolution, which permits a noninvasive 3-D measurement and quantification of airway geometry. In different diseases, like emphysema, chronic obstructive pulmonary disease (COPD), or cystic fribrosis, changes in lung parenchyma are associated with an increase in airway wall thicknes...

多排X射线计算机断层扫描（MSCT）技术提供了具有近似各向同性分辨率的体积数据集，从而能够对气道几何形态进行非侵入性的三维测量和量化。在不同疾病中，如肺气肿、慢性阻塞性肺疾病（COPD）或囊性纤维化，肺实质的变化伴随着气道壁增厚...

Radial imaging techniques, such as projection-reconstruction (PR), are used in magnetic resonance imaging (MRI) for dynamic imaging, angiography, and short- imaging. They are robust to flow and motion, have diffuse aliasing patterns, and support short readouts and echo times. One drawback is that standard implementations do not support anisotropic field-of-view (FOV) shapes, which are used to matc...

径向成像技术，如投影重建（PR），用于磁共振成像（MRI）中的动态成像、血管造影和短成像。它们对流动和运动具有鲁棒性，具有弥散的混叠模式，并支持短读出和回波时间。一个缺点是标准实现不支持各向异性视野（FOV）形状，这些形状用于匹配...

In medical image processing, many filters have been developed to enhance certain structures in 3-D data. In this paper, we propose to use pattern recognition techniques to design more optimal filters. The essential difference with previous approaches is that we provide a system with examples of what it should enhance and suppress. This training data is used to construct a classifier that determine...

在医学图像处理中，已经开发了许多滤波器来增强三维数据中的特定结构。本文提出使用模式识别技术来设计更优化的滤波器。与先前方法的主要区别在于，我们向系统提供了应增强和抑制的示例。这些训练数据用于构建一个分类器，以确定...

High-resolution functional imaging of small animals is often obtained by single pinhole SPECT with circular orbit acquisition. Multipinhole SPECT adds information due to its improved sampling, and can improve the trade-off between resolution and sensitivity. To evaluate different pinhole collimator designs an efficient method is needed that quantifies the reconstruction image quality. In this pape...

小动物的高分辨率功能成像通常通过使用圆形轨道采集的单针孔SPECT获得。多针孔SPECT因其改进的采样而增加了信息，并能改善分辨率和灵敏度之间的权衡。为了评估不同的针孔准直器设计，需要一种能够量化重建图像质量的有效方法。本文...

For nearly four decades, adaptive beamforming (ABF) algorithms have been applied in RADAR and SONAR signal processing. These algorithms reduce the contribution of undesired off-axis signals while maintaining a desired response along a specific look direction. Typically, higher resolution and contrast is attainable using adaptive beamforming at the price of an increased computational load. In this ...

近四十年来，自适应波束形成（ABF）算法已应用于雷达和声纳信号处理。这些算法在保持特定观测方向上的所需响应的同时，减少了不必要的离轴信号的贡献。通常，使用自适应波束形成可以获得更高的分辨率和对比度，但代价是计算负荷增加。在这……

We present a phantom study to evaluate the performance of the eXplore Optix (Advanced Research Technologies-GE Healthcare), the first commercially available time-domain tomography system for small animal fluorescence imaging, and compare its capabilities with the widely used IVIS 200 (Xenogen Corporation-Caliper) continuous wave planar imaging system. The eXplore Optix, based on point-wise illumin...

我们提出了一项体模研究，以评估eXplore Optix（Advanced Research Technologies-GE Healthcare）的性能，这是首个商用的用于小动物荧光成像的时域断层成像系统，并将其与广泛使用的IVIS 200（Xenogen Corporation-Caliper）连续波平面成像系统进行比较。eXplore Optix基于逐点照明...

We propose a new method for detecting activation in functional magnetic resonance imaging (fMRI) data. We project the fMRI time series on a low-dimensional subspace spanned by wavelet packets in order to create projections that are as non-Gaussian as possible. Our approach achieves two goals: it reduces the dimensionality of the problem by explicitly constructing a sparse approximation to the data...

我们提出了一种检测功能磁共振成像（fMRI）数据中激活的新方法。我们将fMRI时间序列投影到由小波包张成的低维子空间上，以创建尽可能非高斯化的投影。我们的方法实现了两个目标：通过显式构建数据的稀疏近似来降低问题的维度，同时利用空间先验信息提高激活检测的准确性。

Prepolarized magnetic resonance imaging (PMRI) uses two pulsed electromagnets to achieve high-field image quality with the benefits of low-field data acquisition. The principal challenge with all resistive MRI systems is the implementation of a highly precise magnet current supply. The noise current through the magnet is fundamentally limited by the current transducer used to provide feedback and ...

预极化磁共振成像（PMRI）使用两个脉冲电磁铁，以低场数据采集的优势实现高场图像质量。所有电阻性MRI系统的主要挑战是实现高精度的磁体电流供应。通过磁体的噪声电流从根本上受限于用于提供反馈的电流传感器...

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