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When time-varying gradients are used for imaging, the off-resonance behavior does not just cause geometric distortion as is the case with spin-warp imaging, but changes the shape of the impulse response and causes blurring. This effect is well known for projection reconstruction and spiral k-space scanning sequences. The authors introduce a reconstruction and homogeneity correction method to corre...

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This paper describes research work motivated by an innovative medical application: computer-assisted transbronchial biopsy. This project involves the registration, with no external localization device, of a preoperative three-dimensional (3-D) computed tomography (CT) scan of the thoracic cavity (showing a tumor that requires a needle biopsy), and an intraoperative endoscopic two-dimensional (2-D)...

本文描述了由一项创新医学应用（计算机辅助经支气管活检）所驱动的研究工作。该项目涉及在无外部定位设备的情况下，将术前三维胸部CT扫描（显示需要针吸活检的肿瘤）与术中二维内镜图像进行配准...

The image restoration theory discussed in a previous paper by Youla and Webb [1] is applied to a simulated image and the results compared with the well-known method known as the Gerchberg-Papoulis algorithm. The results show that the method of image restoration by projection onto convex sets, by providing a convenient technique for utilizing a priori information, performs significantly better than...

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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...

A method is introduced to compensate for missing projection data that can result from gas between detectors or from malfunctioning detectors. This method uses constraints in the Fourier domain to estimate the missing data, thus completing the data set so that the filtered backprojection algorithm can be used to reconstruct artifact-free images. The image reconstructed from estimates using this tec...

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Image registration is a real challenge because physicians handle many images. Temporal registration is necessary in order to follow the various steps of a disease, whereas multimodal registration allows us to improve the identification of some lesions or to compare pieces of information gathered from different sources. This paper presents an algorithm for temporal and/or multimodal registration of...

图像配准是一个真正的挑战，因为医生需要处理大量图像。为了跟踪疾病的不同阶段，时间配准是必要的，而多模态配准则使我们能够改善某些病变的识别或比较来自不同来源的信息。本文提出了一种用于眼底图像的时间和/或多模态配准算法...

In this article, multiresolution analysis, specifically the discrete wavelet transform modulus-maxima (mod-max) method, is utilized for the extraction of mammographic mass shape features. These shape features are used in a classification system to classify masses as round, nodular, or stellate. The multiresolution shape features are compared with traditional uniresolution shape features for their ...

本文采用多分辨率分析，特别是离散小波变换模极大值（mod-max）方法，用于提取乳腺肿块形状特征。这些形状特征用于分类系统，将肿块分为圆形、结节状或星状。将多分辨率形状特征与传统的单分辨率形状特征进行比较...

Computer-aided classification of benign and malignant masses on mammograms is attempted in this study by computing gradient-based and texture-based features. Features computed based on gray-level co-occurrence matrices (GCMs) are used to evaluate the effectiveness of textural information possessed by mass regions in comparison with the textural information present in mass margins. A method involving polygonal modeling of boundaries is proposed for the extraction of a ribbon of pixels across mass margins. Two gradient-based features are developed to estimate the sharpness of mass boundaries in the ribbons of pixels extracted from their margins. A total of 54 images (28 benign and 26 malignant) containing 39 images from the Mammographic Image Analysis Society (MIAS) database and 15 images from a local database are analyzed. The best benign versus malignant classification of 82.1%, with an area (A/sub z/) of 0.85 under the receiver operating characteristics (ROC) curve, was obtained with the images from the MIAS database by using GCM-based texture features computed from mass margins. The classification method used is based on posterior probabilities computed from Mahalanobis distances. The corresponding accuracy using jack-knife classification was observed to be 74.4%, with A/sub x/=0.67. Gradient-based features achieved A/sub x/=0.6 on the MIAS database and A/sub z/=0.76 on the combined database. The corresponding values obtained using jack-knife classification were observed to be 0.52 and 0.73 for the MIAS and combined databases, respectively.

本研究尝试通过计算基于梯度和基于纹理的特征，对乳腺X线图像上的良性和恶性肿块进行计算机辅助分类。使用基于灰度共生矩阵（GCM）计算的特征，评估肿块区域所拥有的纹理信息与肿块边缘存在的纹理信息相比的有效性。提出了一种涉及边界多边形建模的方法，用于提取跨肿块边缘的像素带。开发了两种基于梯度的特征来估计从肿块边缘提取的像素带中边界的锐度。共分析了54幅图像（28幅良性，26幅恶性），其中39幅来自乳腺X线图像分析学会（MIAS）数据库，15幅来自本地数据库。使用从MIAS数据库图像中基于GCM的肿块边缘纹理特征，获得了最佳的良性/恶性分类准确率82.1%，受试者工作特征（ROC）曲线下面积（A_z）为0.85。所使用的分类方法基于马氏距离计算的后验概率。使用刀切法分类的相应准确率为74.4%，A_x=0.67。基于梯度的特征在MIAS数据库上达到A_x=0.6，在组合数据库上达到A_z=0.76。使用刀切法分类得到的相应值对于MIAS数据库和组合数据库分别为0.52和0.73。

This paper describes fusion of three-dimensional (3-D) ultrasound (US) and magnetic resonance imaging (MRI) data sets, without the assistance of external fiducial markers or external position sensors. Fusion of these two modalities combines real-time 3-D ultrasound scans of soft tissue with the larger anatomical framework from MRI. The complementary information available from multiple imaging moda...

本文描述了在不使用外部基准标记或外部位置传感器的情况下，三维超声与磁共振成像数据集的融合。这两种模态的融合将软组织的实时三维超声扫描与MRI提供的更大解剖框架相结合。多模态成像提供的互补信息...

A comprehensive methodology for image segmentation is presented. Tools for differential and intensity contouring, and outline optimization are discussed, as well as the methods for automating such procedures. After segmentation, regional volumes and image intensity distributions can be determined. The methodology is applied to nuclear magnetic resonance images of the brain. Examples of the results...

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Advances in visualization technology and specialized graphic workstations allow clinicians to virtually interact with anatomical structures contained within sampled medical-image datasets. A hindrance to the effective use of this technology is the difficult problem of image segmentation. In this paper, the authors utilize a recently proposed oscillator network called the locally excitatory globall...

可视化技术和专业图形工作站的进步使得临床医生能够与采样医学图像数据集中的解剖结构进行虚拟交互。有效利用这一技术的障碍是图像分割这一难题。在本文中，作者利用了一种最近提出的振荡器网络，称为局部兴奋全局...

The cortex is the outermost thin layer of gray matter in the brain; geometric measurement of the cortex helps in understanding brain anatomy and function. In the quantitative analysis of the cortex from MR images, extracting the structure and obtaining a representation for various measurements are key steps. While manual segmentation is tedious and labor intensive, automatic reliable efficient seg...

皮层是大脑最外层的薄层灰质；皮层的几何测量有助于理解大脑解剖和功能。在MR图像的皮层定量分析中，提取结构并获取用于各种测量的表示是关键步骤。手动分割繁琐且劳动密集，而自动、可靠、高效的分割...

Presents a validation study of an optical-flow method for the rapid estimation of myocardial displacement in magnetic resonance tagged cardiac images. This registration and change visualization (RCV) software uses a hierarchical estimation technique to compute the flow field that describes the warping of an image of one cardiac phase into alignment with the next. This method overcomes the requirem...

介绍了一种用于快速估计磁共振标记心脏图像中心肌位移的光流方法的验证研究。该配准与变化可视化（RCV）软件使用分层估计技术来计算描述一个心脏相位图像变形以与下一个相位对齐的光流场。该方法克服了需要...

An approach for tracking and quantifying the nonrigid, nonuniform motion of the left ventricular (LV) endocardial wall from two-dimensional (2-D) cardiac image sequences, on a point-by-point basis over the entire cardiac cycle, is presented. Given a set of boundaries, motion computation involves first matching local segments on one contour to segments on the next contour in the sequence using a sh...

提出了一种在整个心动周期中逐点追踪和量化左心室心内膜壁非刚性、非均匀运动的方法，该方法基于二维心脏图像序列。给定一组边界，运动计算首先涉及使用形状匹配将一个轮廓上的局部段与序列中下一个轮廓上的段进行匹配。

Traditional computed tomography (CT) reconstructions of total joint prostheses are limited by metal artifacts from corrupted projection data. Published metal artifact reduction methods are based on the assumption that severe attenuation of X-rays by prostheses renders corresponding portions of projection data unavailable, hence the "missing" data are either avoided (in iterative reconstruction) or interpolated (in filtered back-projection with data completion; typically, with filling data "gaps" via linear functions). Here, the authors propose a wavelet-based multiresolution analysis method for metal artifact reduction, in which information is extracted from corrupted projection data. The wavelet method improves image quality by a successive interpolation in the wavelet domain. Theoretical analysis and experimental results demonstrate that the metal artifacts due to both photon starving and beam hardening can be effectively suppressed using the authors' method. As compared to the filtered back-projection after linear interpolation, the wavelet-based reconstruction is significantly more accurate for depiction of anatomical structures, especially in the immediate neighborhood of the prostheses. This superior imaging precision is highly advantageous in geometric modeling for fitting hip prostheses.

传统计算机断层扫描（CT）重建全关节假体时，因投影数据受损而产生的金属伪影限制了其应用。已发表的金属伪影减少方法基于以下假设：假体对X射线的严重衰减使得相应的投影数据部分不可用，因此“缺失”数据要么被避免（迭代重建），要么被插值（使用数据完成的滤波反投影；通常通过线性函数填充数据“间隙”）。本文作者提出了一种基于小波的多分辨率分析方法用于金属伪影减少，该方法从受损的投影数据中提取信息。小波方法通过在 wavelet 域中进行连续插值来提高图像质量。理论分析和实验结果表明，使用该方法可以有效抑制由光子饥饿和束硬化引起的金属伪影。与线性插值后的滤波反投影相比，基于小波的重建在描绘解剖结构方面显著更准确，尤其是在假体附近。这种优越的成像精度对于髋关节假体的几何建模非常有利。

Many image matching schemes are based on mapping coordinate locations, such as the locations of landmarks, in one image to corresponding locations in a second image. A new approach to this mapping (coordinate transformation), called the elastic body spline (EBS), is described. The spline is based on a physical model of a homogeneous, isotropic three-dimensional (3-D) elastic body. The model can ap...

许多图像匹配方案基于将一个图像中的坐标位置（如地标位置）映射到第二个图像中的对应位置。本文描述了一种新的映射方法（坐标变换），称为弹性体样条（EBS）。该样条基于均匀、各向同性三维弹性体的物理模型。该模型可以...

We present for the first time a full three-dimensional (3-D) reconstruction of absorption images of breast from continuous-wave (cw) measurements performed on a premenopausal woman. Our 3-D optical images clearly reveal a large primary tumor as well as a small secondary tumor in a separate location of the breast. The multiple tumors identified by our 3-D optical imaging have been confirmed by the ...

我们首次展示了在一位绝经前女性身上进行的连续波（CW）测量所得到的乳腺吸收图像的全三维（3D）重建。我们的3D光学图像清晰地揭示了乳腺内一个大的原发肿瘤以及另一个位置的一个小的继发肿瘤。我们的3D光学成像识别出的多个肿瘤已通过...得到证实。

Proposes and validates the hypothesis that one can use differential shape properties of the myocardial surfaces to recover dense field motion from standard three-dimensional (3-D) image sequences (MRI and CT). Quantitative measures of left ventricular regional function can be further inferred from the point correspondence maps. The noninvasive, algorithm-derived results are validated on two levels...

提出并验证了一种假设，即可以利用心肌表面的微分形状特性从标准三维（3-D）图像序列（MRI和CT）中恢复密集场运动。进一步可以从点对应图中推断出左心室区域功能的定量测量。无创、算法推导的结果在两个层面上得到验证...

The authors have been developing general user steered image segmentation strategies for routine use in applications involving a large number of data sets. In the past, they have presented three segmentation paradigms: live wire, live lane, and a three-dimensional (3-D) extension of the live-wire method. Here, they introduce an ultra-fast live-wire method, referred to as live wire on the fly for further reducing user's time compared to the basic live-wire method. In live wire, 3-D/four-dimensional (4-D) object boundaries are segmented in a slice-by-slice fashion. To segment a two-dimensional (2-D) boundary, the user initially picks a point on the boundary and all possible minimum-cost paths from this point to all other points in the image are computed via Dijkstra's algorithm. Subsequently, a live wire is displayed in real time from the initial point to any subsequent position taken by the cursor. If the cursor is close to the desired boundary, the live wire snaps on to the boundary. The cursor is then deposited and a new live-wire segment is found next. The entire 2-D boundary is specified via a set of live-wire segments in this fashion. A drawback of this method is that the speed of optimal path computation depends on image size. On modestly powered computers, for images of even modest size, some sluggishness appears in user interaction, which reduces the overall segmentation efficiency. In this work, the authors solve this problem by exploiting some known properties of graphs to avoid unnecessary minimum-cost path computation during segmentation. In live wire on the fly, when the user selects a point on the boundary the live-wire segment is computed and displayed in real time from the selected point to any subsequent position of the cursor in the image, even for large images and even on low-powered computers. Based on 492 tracing experiments from an actual medical application, the authors demonstrate that live wire on the fly is 1.331 times faster than live wire for actual segmentation for varying image sizes, although the pure computational part alone is found to be about 120 times faster.

作者一直致力于开发通用的用户引导图像分割策略，用于涉及大量数据集的常规应用。过去，他们提出了三种分割范式：活动线、活动车道以及活动线方法的三维（3-D）扩展。在此，他们介绍了一种超快速的活动线方法，称为即时活动线，以进一步减少用户时间相比基本活动线方法。在活动线中，3-D/四维（4-D）物体边界以逐切片方式分割。为了分割二维（2-D）边界，用户首先在边界上选取一个点，然后通过Dijkstra算法计算从该点到图像中所有其他点的所有最小代价路径。随后，从初始点到光标随后位置的即时活动线实时显示。如果光标接近期望边界，活动线会捕捉到边界上。然后放置光标，接着找到新的活动线段。整个二维边界通过一组活动线段以这种方式指定。该方法的缺点是，最优路径计算的速度取决于图像大小。在性能一般的计算机上，即使是中等大小的图像，用户交互也会出现一些迟缓，这降低了整体分割效率。在本工作中，作者通过利用图的一些已知属性来避免分割过程中不必要的代价路径计算，从而解决了这个问题。在即时活动线中，当用户在边界上选择一个点时，活动线段从所选点到图像中光标随后位置实时计算并显示，即使对于大图像和低性能计算机也是如此。基于来自实际医学应用的492次追踪实验，作者证明，对于不同图像大小的实际分割，即时活动线比活动线快1.331倍，尽管纯计算部分本身大约快120倍。

Within-subject analysis in fMRI essentially addresses two problems, the detection of brain regions eliciting evoked activity and the estimation of the underlying dynamics. In Makni , 2005 and Makni , 2008, a detection-estimation framework has been proposed to tackle these problems jointly, since they are connected to one another. In the Bayesian formalism, detection is achieved by modeling activat...

fMRI的个体内分析主要解决两个问题：检测诱发活动的脑区域以及估计潜在的动态过程。在Makni等人2005年和Makni等人2008年的研究中，提出了一种检测-估计框架来联合处理这些问题，因为它们相互关联。在贝叶斯形式中，通过建模激活来实现检测……

This paper presents a method for segmentation and tracking of cardiac structures in ultrasound image sequences. The developed algorithm is based on the active contour framework. This approach requires initial placement of the contour close to the desired position in the image, usually an object outline. Best contour shape and position are then calculated, assuming that at this configuration a glob...

本文提出了一种在超声图像序列中对心脏结构进行分割与跟踪的方法。所开发的算法基于主动轮廓框架。该方法需要将轮廓初始放置在图像中接近目标位置（通常是物体轮廓）处。然后计算最佳轮廓形状和位置，假设在该配置下，能量泛函达到全局最小值。

In recent years, many investigators have proposed Gibbs prior models to regularize images reconstructed from emission computed tomography data. Unfortunately, hyperparameters used to specify Gibbs priors can greatly influence the degree of regularity imposed by such priors and, as a result, numerous procedures have been proposed to estimate hyperparameter values, from observed image data. Many of ...

近年来，许多研究者提出使用吉布斯先验模型来正则化从发射计算机断层扫描数据重建的图像。不幸的是，用于指定吉布斯先验的超参数会极大影响这些先验所施加的正则化程度，因此，已提出许多从观测图像数据估计超参数值的方法。许多...

The phase correlation method (PCM) is known to provide straightforward estimation of rigid translational motion between two images. It is often claimed that the original method is best suited to identify integer pixel displacements, which has prompted the development of numerous subpixel displacement identification methods. However, the fact that the phase correlation matrix is rank one for a nois...

相位相关法（PCM）能够直接估计两幅图像之间的刚性平移运动。通常认为原始方法最适合识别整数像素位移，这促使了众多亚像素位移识别方法的发展。然而，相位相关矩阵对于无噪声情况是秩为1的...

Images formed with endoscopes suffer from a spatial distortion due to the wide-angle nature of the endoscope's objective lens. This change in the size of objects with position precludes quantitative measurement of the area of the objects, which is important in endoscopy for accurately measuring ulcer and lesion sizes over time. A method for correcting the distortion characteristic of endoscope ima...

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It is known that when the maximum likelihood estimator (MLE) algorithm passes a certain point, it produces images that begin to deteriorate. We propose a quantitative criterion with a simple probabilistic interpretation that allows the user to stop the algorithm just before this effect begins. The MLE algorithm searches for the image that has the maximum probability to generate the projection data...

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