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The majority of functional magnetic resonance imaging (fMRI) studies obtain functional information using statistical tests based on the magnitude image reconstructions. Recently, a complex correlation (CC) test was proposed based on the complex image data in order to take advantage of phase information in the signal. However, the CC test ignores additional phase information in the baseline compone...

大多数功能磁共振成像（fMRI）研究使用基于幅度图像重建的统计检验来获取功能信息。最近，提出了基于复数图像数据的复数相关（CC）测试，以利用信号中的相位信息。然而，CC测试忽略了基线分量中的额外相位信息...

A multiresolution statistical method for identifying clinically normal tissue in digitized mammograms is used to construct an algorithm for separating normal regions from potentially abnormal regions; that is, small regions that may contain isolated calcifications. This is the initial phase of the development of a general method for the automatic recognition of normal mammograms. The first step is...

一种用于识别数字化乳腺X线摄影中临床正常组织的多元统计方法，用于构建一种将正常区域与可能异常区域（即可能含有孤立钙化点的小区域）分离的算法。这是开发自动识别正常乳腺X线图像通用方法的初始阶段。第一步是...

The usefulness of statistical clustering algorithms developed for automatic segmentation of lesions and organs in magnetic resonance imaging (MRI) intensity data sets suffers from spatial nonstationarities introduced into the data sets by the acquisition instrumentation. The major intensity inhomogeneity in MRI is caused by variations in the B1-field of the radio frequency (RF) coil. A three-step ...

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A barrier to the adoption of non-Cartesian parallel magnetic resonance imaging for real-time applications has been the times required for the image reconstructions. These times have exceeded the underlying acquisition time thus preventing real-time display of the acquired images. We present a reconstruction algorithm for commodity graphics hardware (GPUs) to enable real time reconstruction of sens...

非笛卡尔并行磁共振成像在实时应用中的障碍之一是图像重建所需的时间。这些时间超过了底层采集时间，从而阻止了采集图像的实时显示。我们提出了一种用于商用图形硬件（GPU）的重建算法，以实现灵敏度的实时重建...

The use of the wavelet transform is explored for the detection of differences between brain functional magnetic resonance images (fMRIs) acquired under two different experimental conditions. The method benefits from the fact that a smooth and spatially localized signal can be represented by a small set of localized wavelet coefficients, while the power of white noise is uniformly spread throughout...

探索使用小波变换来检测在两种不同实验条件下获取的脑功能磁共振图像（fMRIs）之间的差异。该方法得益于这样一个事实：平滑且空间局部化的信号可以用少量局部小波系数表示，而白噪声的功率均匀分布在整个...

A method is described for the automated detection of microcalcifications in digitized mammograms. The method is based on the Laplacian scale-space representation of the mammogram only. First, possible locations of microcalcifications are identified as local maxima in the filtered image on a range of scales. For each finding, the size and local contrast is estimated, based on the Laplacian response...

描述了一种用于数字化乳腺X线摄影中微钙化自动检测的方法。该方法仅基于乳腺X线摄影的拉普拉斯尺度空间表示。首先，在一系列尺度上，将微钙化的可能位置识别为滤波后图像中的局部最大值。对于每个发现，根据拉普拉斯响应估计其大小和局部对比度...

A regularized color clustering algorithm is proposed to solve the color clustering problem in medical image database. By incorporating both measures of cluster separability and cluster compactness, regularized color clustering allows the automatic extraction of significant color groups with varying populations. Experimental results in different color spaces show that the regularized color clusteri...

提出了一种正则化颜色聚类算法来解决医学图像数据库中的颜色聚类问题。通过同时考虑聚类分离度和聚类紧致度，正则化颜色聚类能够自动提取具有不同种群数量的重要颜色组。在不同颜色空间中的实验结果表明，正则化颜色聚类...

This paper describes a new approach to reconstruction of the conductivity field in electrical impedance tomography. Our goal is to improve the tradeoff between the quality of the images and the numerical complexity of the reconstruction method. In order to reduce the computational load, we adopt a linearized approximation to the forward problem that describes the relationship between the unknown c...

本文描述了一种在电阻抗断层成像中重建电导率场的新方法。我们的目标是改善图像质量与重建方法数值复杂度之间的权衡。为了降低计算负荷，我们采用正向问题的线性化近似，描述未知电导率与测量数据之间的关系。

An algorithm is developed that detects well-localized, unfragmented, thin edges in medical images based on optimization of edge configurations using a genetic algorithm (GA). Several enhancements were added to improve the performance of the algorithm over a traditional GA. The edge map is split into connected subregions to reduce the solution space and simplify the problem. The edge-map is then op...

一种算法被开发出来，基于遗传算法（GA）优化边缘配置，用于检测医学图像中定位良好、无碎片、细小的边缘。添加了几项增强功能以提高算法相对于传统GA的性能。边缘图被分割成连通的子区域以减少解空间并简化问题。然后对边缘图进行...

Bag-of-features based approaches have become prominent for image retrieval and image classification tasks in the past decade. Such methods represent an image as a collection of local features, such as image patches and key points with scale invariant feature transform (SIFT) descriptors. To improve the bag-of-features methods, we first model the assignments of local descriptors as contribution fun...

在过去十年中，基于词袋特征的方法已成为图像检索和图像分类任务的主流。这类方法将图像表示为局部特征的集合，例如图像块和具有尺度不变特征变换（SIFT）描述符的关键点。为了改进词袋特征方法，我们首先将局部描述符的分配建模为贡献函数...

This article presents a detailed description of an algorithm for the automatic detection of the mid-sagittal plane in three-dimensional (3-D) brain images. The algorithm seeks the plane with respect to which the image exhibits maximum symmetry. For a given plane, symmetry is measured by the cross-correlation between the image sections lying on either side. The search for the plane of maximum symme...

本文详细介绍了一种用于三维脑图像中矢状面自动检测的算法。该算法寻找使图像表现出最大对称性的平面。对于给定平面，对称性通过两侧图像区域之间的互相关来测量。寻找最大对称性平面的搜索...

Preliminary evaluation of recently developed large-area flat panel detectors (FPDs) indicates that FPDs have some potential advantages: compactness, absence of geometric distortion and veiling glare with the benefits of high resolution, high detective quantum efficiency (DQE), high frame rate and high dynamic range, small image lag (<1%), and excellent linearity (/spl sim/1%). The advantages of the new FPD make it a promising candidate for cone-beam volume computed tomography (CT) angiography (CBVCTA) imaging. The purpose of this study is to characterize a prototype FPD-based imaging system for CBVCTA applications. A prototype FPD-based CBVCTA imaging system has been designed and constructed around a modified GE 8800 CT scanner. This system is evaluated for a CBVCTA imaging task in the head and neck using four phantoms and a frozen rat. The system is first characterized in terms of linearity and dynamic range of the detector. Then, the optimal selection of kVps for CBVCTA is determined and the effect of image lag and scatter on the image quality of the CBVCTA system is evaluated. Next, low-contrast resolution and high-contrast spatial resolution are measured. Finally, the example reconstruction images of a frozen rat are presented. The results indicate that the FPD-based CBVCT can achieve 2.75-1p/mm spatial resolution at 0% modulation transfer function (MTF) and provide more than enough low-contrast resolution for intravenous CBVCTA imaging in the head and neck with clinically acceptable entrance exposure level. The results also suggest that to use an FPD for large cone-angle applications, such as body angiography, further investigations are required.

最近开发的大面积平板探测器（FPD）的初步评估表明，FPD具有一些潜在优势：紧凑性、无几何失真和光晕，同时具有高分辨率、高探测量子效率（DQE）、高帧率、高动态范围、小图像滞后（<1%）和优异的线性度（/spl sim/1%）。新型FPD的这些优势使其成为锥束容积计算机断层扫描（CT）血管成像（CBVCTA）的有前景候选。本研究旨在表征一种用于CBVCTA应用的原型FPD成像系统。围绕改进的GE 8800 CT扫描仪设计和构建了一种基于FPD的原型CBVCTA成像系统。使用四个体模和一只冷冻大鼠对该系统在头颈部CBVCTA成像任务中进行评估。首先根据探测器的线性度和动态范围进行表征。然后确定CBVCTA的最佳千伏峰值选择，并评估图像滞后和散射对CBVCTA系统图像质量的影响。接下来测量低对比度分辨率和高对比度空间分辨率。最后展示冷冻大鼠的重建图像示例。结果表明，基于FPD的CBVCT可以在0%调制传递函数（MTF）下达到2.75线对/毫米的空间分辨率，并在临床可接受的入射暴露水平下为头颈部静脉内CBVCTA成像提供足够高的低对比度分辨率。结果还提示，将FPD用于大锥角应用（如体部血管成像）需要进一步研究。

A high spatial resolution brain positron tomograph, the ECAT 953B/31, is presented. The machine consists of two 76.5 cm diameter rings (patient port diameter: 36 cm) made of 24 8*8 BGO detector blocks each, each block being coupled to four 1 in/sup 2/ Hammamatsu phototubes. The machine has 15 9 cm*1 mm motorized removable septa, which allows reconstruction of 31 slices 3.375 mm apart. The transaxi...

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Monte Carlo (MC) methods can accurately simulate scatter in X-ray imaging. However, when low noise scatter projections have to be simulated these MC simulations tend to be very time consuming. Rapid computation of scatter estimates is essential for several applications. The aim of the work presented in this paper is to speed up the estimation of noise-free scatter projections while maintaining the...

蒙特卡洛（MC）方法能够准确模拟X射线成像中的散射。然而，当需要模拟低噪声散射投影时，这些MC模拟往往非常耗时。快速计算散射估计对于多种应用至关重要。本文旨在加速无噪声散射投影的估计，同时保持...

The likelihood ratio, or ideal observer, decision rule is known to be optimal for two-class classification tasks in the sense that it maximizes expected utility (or, equivalently, minimizes the Bayes risk). Furthermore, using this decision rule yields a receiver operating characteristic (ROC) curve which is never above the ROC curve produced using any other decision rule, provided the observer's m...

似然比（即理想观察者）决策规则已知在二类分类任务中是最优的，因为它最大化期望效用（或者等价地，最小化贝叶斯风险）。此外，使用该决策规则得到的接收者操作特征（ROC）曲线永远不会高于使用任何其他决策规则得到的ROC曲线，前提是观察者的m...

For implementations of iterative reconstruction algorithms that rotate the image matrix, the characteristics of the rotator may affect the reconstruction quality. Desirable qualities for the rotator include: (1) preservation of global and local image counts; (2) accurate count positioning; (3) a uniform and predictable amount of blurring due to the rotation. A new rotation method for iterative rec...

对于旋转图像矩阵的迭代重建算法的实现，旋转器的特性可能会影响重建质量。旋转器所需的特性包括：(1) 保持全局和局部图像计数；(2) 准确的计数定位；(3) 由于旋转而产生的均匀且可预测的模糊量。一种用于迭代重...

The notion of a linogram is introduced. It corresponds to the notion of a sinogram in the conventional representation of projection data in image reconstruction. In the sinogram, points which correspond to rays which go through a fixed point in the cross section to be reconstructed all fall on a sinusoidal curve. In the linogram, however, these points fall on a straight line. Thus, backprojection ...

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This paper presents a new reconstruction algorithm for both single- and dual-energy computed tomography (CT) imaging. By incorporating the polychromatic characteristics of the X-ray beam into the reconstruction process, the algorithm is capable of eliminating beam hardening artifacts. The single energy version of the algorithm assumes that each voxel in the scan field can be expressed as a mixture...

本文提出了一种用于单能量和双能量计算机断层扫描（CT）成像的新型重建算法。通过将X射线束的多色特性纳入重建过程，该算法能够消除射束硬化伪影。该算法的单能量版本假设扫描场中的每个体素可以表示为混合物...

Nuclear magnet resonance (NMR) imaging in the presence of large static field nonuniformity is presented. The method involves three steps: field mapping, imaging by a conventional method, and image restoration from nonuniform field influence. Two-dimensional experiments are performed to demonstrate effectiveness of this method, as well as to clarify practical problems in employing the method. Exper...

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Phase contrast magnetic resonance imaging (MRI) can provide in vivo myocardial velocity field measurements. These data allow densely spaced material points to be tracked throughout the whole heart cycle using, for example, the Fourier tracking algorithm. To process the tracking results for myocardial deformation and strain quantification, the authors developed a method that is based on fitting the...

相位对比磁共振成像（MRI）可以提供体内心肌速度场测量。这些数据允许使用例如傅里叶跟踪算法在整个心动周期中追踪密集分布的物质点。为了处理追踪结果以量化心肌变形和应变，作者开发了一种基于拟合...的方法。

Images captured with a typical endoscope show spatial distortion, which necessitates distortion correction for subsequent analysis. Here, a new methodology based on least squares estimation is proposed to correct the nonlinear distortion in the endoscopic images. A mathematical model based on polynomial mapping is used to map the images from distorted image space onto the corrected image space. Th...

使用典型内窥镜捕获的图像存在空间畸变，这需要畸变校正以便后续分析。本文提出了一种基于最小二乘估计的新方法来校正内窥镜图像中的非线性畸变。采用基于多项式映射的数学模型将图像从畸变图像空间映射到校正后的图像空间。

Presents the design of a positron emission tomograph (PET) with flexible geometry dedicated to in vivo studies of small animals (TierPET). The scanner uses two pairs of detectors. Each detector consists of 400 small individual yttrium aluminum perovskite (YAP) scintillator crystals of dimensions 2/spl times/2/spl times/15 mm/sup 3/, optically isolated and glued together, which are coupled to posit...

介绍一种用于小动物体内研究的柔性几何正电子发射断层扫描仪（TierPET）的设计。该扫描仪使用两对探测器。每个探测器由400个尺寸为2×2×15 mm³的小型钇铝钙钛矿（YAP）闪烁晶体组成，这些晶体光学隔离并粘合在一起，耦合到正电子...

This paper proposes an adaptive image enhancement method for mammographic images, which is based on the first derivative and the local statistics. The adaptive enhancement method consists of three processing steps. The first step is to remove the film artifacts which may be misread as microcalcifications. The second step is to compute the gradient images by using the first derivative operators. Th...

本文提出了一种基于一阶导数和局部统计的自适应乳腺X线图像增强方法。该自适应增强方法包括三个处理步骤。第一步是去除可能被误读为微钙化的胶片伪影。第二步是利用一阶导数算子计算梯度图像。

Locally adaptive image binarization with a sliding-window threshold can be an effective tool for various image processing tasks. We have used the method for the detection of bone ridges in radiotherapy portal images. However, a straight-forward implementation of sliding-window processing is too time consuming for routine use. Therefore, we have developed a new thresholding criterion suitable for i...

局部自适应图像二值化使用滑动窗口阈值可以有效地处理各种图像处理任务。我们已将该方法用于放疗门户图像中骨脊的检测。然而，滑动窗口处理的直接实现对于常规使用来说过于耗时。因此，我们开发了一种新的阈值化准则，适用于...

Reconstruction of images in electrical impedance tomography requires the solution of a nonlinear inverse problem on noisy data. This problem is typically ill-conditioned and requires either simplifying assumptions or regularization based on a priori knowledge. The authors present a reconstruction algorithm using neural network techniques which calculates a linear approximation of the inverse probl...

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