Volume 17, Issue 4

A comparison of six similarity measures for use in intensity-based two-dimensional-three-dimensional (2-D-3-D) image registration is presented. The accuracy of the similarity measures are compared to a "gold-standard" registration which has been accurately calculated using fiducial markers. The similarity measures are used to register a computed tomography (CT) scan of a spine phantom to a fluoroscopy image of the phantom. The registration is carried out within a region-of-interest in the fluoroscopy image which is user defined to contain a single vertebra. Many of the problems involved in this type of registration are caused by features which were not modeled by a phantom image alone. More realistic "gold-standard" data sets were simulated using the phantom image with clinical image features overlaid. Results show that the introduction of soft-tissue structures and interventional instruments into the phantom image can have a large effect on the performance of some similarity measures previously applied to 2-D-3-D image registration. Two measures were able to register accurately and robustly even when soft-tissue structures and interventional instruments were present as differences between the images. These measures were pattern intensity and gradient difference. Their registration accuracy, for all the rigid-body parameters except for the source to film translation, was within a root-mean-square (rms) error of 0.53 mm or degrees to the "gold-standard" values. No failures occurred while registering using these measures.

本文比较了六种基于强度的二维-三维（2-D-3-D）图像配准中的相似性度量。这些相似性度量的精度与使用基准标记精确计算的金标准配准进行了比较。这些相似性度量用于将脊柱模型的计算机断层扫描（CT）图像注册到荧光透视图像...

This paper presents an algorithm for speckle reduction and contrast enhancement of echocardiographic images. Within a framework of multiscale wavelet analysis, the authors apply wavelet shrinkage techniques to eliminate noise while preserving the sharpness of salient features. In addition, nonlinear processing of feature energy is carried out to enhance contrast within local structures and along o...

本文提出了一种用于超声心动图像散斑减少和对比度增强的算法。在多尺度小波分析的框架内，作者应用小波收缩技术来消除噪声，同时保持显著特征的清晰度。此外，对特征能量进行非线性处理，以增强局部结构内和沿...的对比度。

Segmenting lesions is a vital step in many computerized mass-detection schemes for digital (or digitized) mammograms. The authors have developed two novel lesion segmentation techniques-one based on a single feature called the radial gradient index (RGI) and one based on simple probabilistic models to segment mass lesions, or other similar nodular structures, from surrounding background. In both m...

分割病变是许多计算机化数字（或数字化）乳腺X线摄影肿块检测方案中的关键步骤。作者开发了两种新颖的病变分割技术——一种基于单一特征即径向梯度指数（RGI），另一种基于简单的概率模型，用于从周围背景中分割肿块病变或其他类似结节结构。两种方法都……

The adaptive contrast enhancement (ACE) algorithm, which uses contrast gains (CGs) to adjust the high-frequency components of images, is a well-known technique for medical image processing. Conventionally, the CG is either a constant or inversely proportional to the local standard deviation (LSD). However, it is known that conventional approaches entail noise overenhancement and ringing artifacts....

自适应对比度增强（ACE）算法利用对比度增益（CG）调整图像的高频分量，是一种众所周知的医学图像处理技术。传统上，CG要么是常数，要么与局部标准差（LSD）成反比。然而，众所周知，传统方法会导致噪声过度增强和振铃伪影...

This paper presents an approach for detecting micro-calcifications in digital mammograms employing wavelet-based subband image decomposition. The microcalcifications appear in small clusters of few pixels with relatively high intensity compared with their neighboring pixels. These image features can be preserved by a detection system that employs a suitable image transform which can localize the s...

本文提出了一种基于小波子带图像分解的数字乳腺X线摄影中微钙化检测方法。微钙化表现为与相邻像素相比具有较高强度的少数像素的小簇。这些图像特征可以通过采用合适图像变换的检测系统来保留，该变换可以定位...

Motivated by the observation that the diagonal pattern of intensity nonuniformity usually associated with linearly polarized radio-frequency (RF) coils is often present in neurological scans using circularly polarized coils, a theoretical analysis has been conducted of the intensity nonuniformity inherent in imaging an elliptically shaped object using 1.5-T magnets and circularly polarized RF coil...

受观察到的现象启发，即通常与线性极化射频线圈相关的强度非均匀性的对角模式常常出现在使用圆极化线圈的神经扫描中，我们对使用1.5T磁体和圆极化射频线圈对椭圆形状物体进行成像时固有的强度非均匀性进行了理论分析...

The new therapeutic method of scotoma-based photocoagulation (SBP) developed at the Vienna Eye Clinic for diagnosis and treatment of age-related macular degeneration requires retinal maps from scanning laser ophthalmoscope images. This paper describes in detail all necessary image analysis steps for map generation. A prototype software system for fully automatic map generation has been implemented...

维也纳眼科诊所开发的基于暗点光凝（SBP）的新治疗方法用于诊断和治疗年龄相关性黄斑变性，需要从扫描激光检眼镜图像中获取视网膜图谱。本文详细描述了生成图谱所需的所有图像分析步骤。已经实现了一个用于全自动图谱生成的原型软件系统……

To aid in the display, manipulation, and analysis of biomedical image data, they usually need to be converted to data of isotropic discretization through the process of interpolation. Traditional techniques consist of direct interpolation of the grey values. When user interaction is called for in image segmentation, as a consequence of these interpolation methods, the user needs to segment a much ...

为了辅助生物医学图像数据的显示、操作和分析，通常需要通过插值过程将其转换为各向同性离散化的数据。传统技术包括对灰度值进行直接插值。当在图像分割中需要用户交互时，由于这些插值方法，用户需要分割更多的...

In a previous study (J.B. West et al., J. Comput. Assist. Tomogr., vol. 21, p. 554-66, 1997) the authors demonstrated that automatic retrospective registration algorithms can frequently register magnetic resonance (MR) and computed tomography (CT) images of the brain with an accuracy of better than 2 mm, but in that same study the authors found that such algorithms sometimes fail, leading to error...

在之前的一项研究（J.B. West等人，《计算机辅助断层扫描杂志》，第21卷，第554-66页，1997年）中，作者证明了自动回顾性配准算法通常能够以优于2毫米的精度配准脑部磁共振（MR）和计算机断层扫描（CT）图像，但在同一研究中，作者发现此类算法有时会失败，导致误差...

This paper presents microwave tomographic reconstructions of the complex permittivity of lossy dielectric objects immersed in water from experimental multiview near-field data obtained with a 2.35-GHz planar active microwave camera. An iterative reconstruction algorithm based on the Levenberg-Marquardt method was used to solve the nonlinear matrix equation which results when applying a moment meth...

本文介绍了利用2.35 GHz平面有源微波相机获得的实验多视近场数据，对浸没在水中的有耗介电物体的复介电常数进行微波层析重建。采用基于Levenberg-Marquardt方法的迭代重建算法来求解应用矩量法时产生的非线性矩阵方程...

Three-dimensional (3-D) analysis of airway trees extracted from computed tomography (CT) image data can provide objective information about lung structure and function. However, manual analysis of 3-D lung CT images is tedious, time consuming and, thus, impractical for routine clinical care. The authors have previously reported an automated rule-based method for extraction of airway trees from 3-D...

从计算机断层扫描（CT）图像数据中提取气道树的三维（3-D）分析可以提供关于肺结构和功能的客观信息。然而，手动分析3-D肺部CT图像繁琐、耗时，因此在常规临床护理中不实用。作者之前报道了一种基于规则的自动化方法，用于从3-D...

This paper describes a new approach for texture characterization, based on nonseparable wavelet decomposition, and its application for the discrimination of visually similar diffuse diseases of liver. The proposed feature-extraction algorithm applies nonseparable quincunx wavelet transform and uses energies of the transformed regions to characterize textures. Classification experiments on a set of...

本文描述了一种基于不可分离小波分解的纹理表征新方法，及其在区分肝脏视觉相似弥漫性疾病中的应用。所提出的特征提取算法采用不可分离的五株形小波变换，并利用变换区域的能量来表征纹理。针对一组...的分类实验

In this paper implicit representations of deformable models for medical image enhancement and segmentation are considered. The advantage of implicit models over classical explicit models is that their topology can be naturally adapted to objects in the scene. A geodesic formulation of implicit deformable models is especially attractive since it has the energy minimizing properties of classical mod...

本文考虑用于医学图像增强和分割的可变形模型的隐式表示。隐式模型相对于经典显式模型的优势在于其拓扑结构可以自然地适应场景中的物体。隐式可变形模型的测地线公式尤其吸引人，因为它具有经典模型的能量最小化特性……

For newly developed iterative Newton-Kantorovitch reconstruction techniques, the quality of the final image depends on both experimental and model noise. Experimental noise is inherent to any experimental acquisition scheme, while model noise refers to the accuracy of the numerical model, used in the reconstruction process, to reproduce the experimental setup. This paper provides a systematic asse...

对于新发展的迭代牛顿-坎托罗维奇重建技术，最终图像的质量取决于实验噪声和模型噪声。实验噪声是任何实验采集方案固有的，而模型噪声指的是重建过程中用于再现实验设置的数值模型的精度。本文提供了一种系统的评估...

In this paper a method for the objective assessment of burn scars is proposed. The quantitative measures developed in this research provide an objective way to calculate elastic properties of burn scars relative to the surrounding areas. The approach combines range data and the mechanics and motion dynamics of human tissues. Active contours are employed to locate regions of interest and to find di...

本文提出了一种客观评估烧伤瘢痕的方法。本研究开发的定量测量提供了一种客观计算烧伤瘢痕相对于周围区域的弹性特性的方法。该方法结合了距离数据以及人体组织的力学和运动动力学。采用活动轮廓来定位感兴趣区域并找到...

Digital computed tomographic (CT) data are widely used in three-dimensional (3-D) construction of bone geometry and density features for 3-D modelling purposes. During in vivo CT data acquisition the number of scans must be limited in order to protect patients from the risks related to X-ray absorption. The aim of this work is to automatically define, given a finite number of CT slices, the scanni...

数字计算机断层扫描（CT）数据广泛用于三维（3-D）骨几何和密度特征构建，以进行三维建模。在体内CT数据采集过程中，必须限制扫描次数，以保护患者免受X射线吸收相关的风险。本工作的目的是在给定有限数量的CT切片的情况下，自动定义扫描...

This work investigates the noise properties of O-15 water positron emission tomography (PET) images in an attempt to increase the sensitivity of activation studies. A method for computing the amount of noise within a region of interest (ROI) from the uncertainty in the raw data was implemented for three-dimensional (3-D) PET. The method was used to study the signal-to-noise ratio (SNR) of regions-...

本研究探讨了O-15水正电子发射断层扫描（PET）图像的噪声特性，旨在提高激活研究的灵敏度。实现了一种从原始数据不确定性计算感兴趣区域（ROI）内噪声量的方法，用于三维（3-D）PET。该方法用于研究区域的信噪比（SNR）...