Volume 20, Issue 6

Segmentation of pulmonary X-ray computed tomography (CT) images is a precursor to most pulmonary image analysis applications. This paper presents a fully automatic method for identifying the lungs in three-dimensional (3-D) pulmonary X-ray CT images. The method has three main steps. First, the lung region is extracted from the CT images by gray-level thresholding. Then, the left and right lungs are separated by identifying the anterior and posterior junctions by dynamic programming. Finally, a sequence of morphological operations is used to smooth the irregular boundary along the mediastinum in order to obtain results consistent with these obtained by manual analysis, in which only the most central pulmonary arteries are excluded from the lung region. The method has been tested by processing 3-D CT data sets from eight normal subjects, each imaged three times at biweekly intervals with lungs at 90% vital capacity. The authors present results by comparing their automatic method to manually traced borders from two image analysts. Averaged over all volumes, the root mean square difference between the computer and human analysis is 0.8 pixels (0.54 mm). The mean intrasubject change in tissue content over the three scans was 2.75%/spl plusmn/2.29% (mean/spl plusmn/standard deviation).

肺X射线计算机断层扫描(CT)图像的分割是大多数肺部图像分析应用的前置步骤。本文提出了一种全自动方法，用于在三维（3D）肺部X射线CT图像中识别肺。该方法包括三个主要步骤。首先，通过灰度阈值从CT图像中提取肺区域。然后，通过动态规划识别前后连接处，将左肺和右肺分离。最后，使用一系列形态学操作沿着纵隔平滑不规则边界，以获得与手动分析一致的结果，其中只有最中心的肺动脉被排除在肺区域之外。该方法通过处理来自八名正常受试者的三维CT数据集进行了测试，每名受试者每隔两周以90%肺活量成像三次。作者通过将其自动方法与两位图像分析师手动追踪的边界进行比较来展示结果。在所有体积上平均，计算机与人工分析之间的均方根差为0.8像素（0.54毫米）。三次扫描中组织含量的平均受试者内变化为2.75%±2.29%（均值±标准差）。

The authors consider elastic image registration based on a set of corresponding anatomical point landmarks and approximating thin-plate splines. This approach is an extension of the original interpolating thin-plate spline approach and allows to take into account landmark localization errors. The extension is important for clinical applications since landmark extraction is always prone to error. T...

作者考虑基于一组对应的解剖点标志点和近似薄板样条的弹性图像配准。该方法是原始插值薄板样条方法的扩展，允许考虑标志点定位误差。这一扩展对于临床应用很重要，因为标志点提取总是容易出错。

A computationally efficient technique is described for the simultaneous removal of ghosting and geometrical distortion artifacts in echo-planar imaging (EPI) utilizing a multiecho, gradient-echo reference scan. Nyquist ghosts occur in EPI reconstructions because odd and even lines of k-space are acquired with opposite polarity, and experimental imperfections such as gradient eddy currents, imperfe...

描述了一种计算效率高的技术，用于利用多回波梯度回波参考扫描同时消除回波平面成像（EPI）中的鬼影和几何失真伪影。奈奎斯特鬼影出现在EPI重建中，因为k空间奇偶行以相反的极性采集，并且由于梯度涡流等实验缺陷，不完美的...

Current noninvasive or minimally invasive methods for evaluating in vivo knee kinematics are inadequate for accurate determination of dynamic joint function due to limited accuracy and/or insufficient sampling rates. A three-dimensional (3-D) model-based method is presented to estimate skeletal motion of the knee from high-speed sequences of biplane radiographs. The method implicitly assumes that ...

当前用于评估在体膝关节运动学的非侵入性或微创方法由于精度有限和/或采样率不足，无法准确确定动态关节功能。本文提出了一种基于三维模型的方法，从高速双平面X射线序列中估计膝关节的骨骼运动。该方法隐含地假设...

This paper presents a method of four-dimensional (4-D) (3-D+Time) space-frequency analysis for directional denoising and enhancement of real-time three-dimensional (RT3D) ultrasound and quantitative measures in diagnostic cardiac ultrasound. Expansion of echocardiographic volumes is performed with complex exponential wavelet-like basis functions called brushlets. These functions offer good localiz...

本文提出了一种四维（4-D）（3-D+时间）空间-频率分析方法，用于实时三维（RT3D）超声的方向性去噪和增强，以及在诊断性心脏超声中的定量测量。超声心动图容积的展开是通过称为brushlets的复指数小波类基函数实现的。这些函数具有良好的局部化...

Classification of benign/malignant microcalcification clusters is a major diagnostic challenge for radiologists. Clinical studies have revealed that the shape of the cluster, and the spatial distribution of individual microcalcifications within it, are important indicators of its malignancy. However, mammographic images of clustered microcalcifications confound their three-dimensional (3-D) distri...

对良恶性微钙化簇的分类是放射科医生面临的主要诊断挑战。临床研究表明，簇的形状以及其中单个微钙化的空间分布是其恶性的重要指标。然而，聚集的微钙化的乳腺X线摄影图像混淆了它们的三维分布...

The authors investigate the performance of diffuse optical tomography to image highly heterogeneous media, such as breast tissue, as a function of background heterogeneity. To model the background heterogeneity, they have employed the functional information derived from Gadolinium-enhanced magnetic resonance images of the breast. The authors demonstrate that overall image quality and quantificatio...

作者研究了漫射光学断层成像对高度异质介质（如乳腺组织）进行成像的性能，作为背景异质性的函数。为了模拟背景异质性，他们利用了从钆增强的乳腺磁共振图像中导出的功能信息。作者证明，整体图像质量和量化...

Cardiac motion estimation is very important in understanding cardiac dynamics and in noninvasive diagnosis of heart disease. Magnetic resonance (MR) imaging tagging is a technique for measuring heart deformations. In cardiac tagged MR images, a set of dark lines are noninvasively encoded within myocardial tissue providing the means for measurement of deformations of the heart. The points along tag...

心脏运动估计对于理解心脏动力学和无创诊断心脏病非常重要。磁共振（MR）成像标记是一种测量心脏变形的方法。在心脏标记MR图像中，一组暗线被无创地编码在心肌组织内，提供了测量心脏变形的手段。沿着标记线的点...

The authors analyze the processing of an inconsistent data function by the FBP algorithm (in its continuous form). Specifically, they demonstrate that an image reconstructed using the FBP algorithm can be represented as the sum of a pseudoinverse solution and a residual image generated from an inconsistent component of the measured data. This reveals that, when the original data function is in the...

作者分析了FBP算法（连续形式）处理不一致数据函数的过程。具体来说，他们证明了使用FBP算法重建的图像可以表示为伪逆解与由测量数据的不一致分量生成的残差图像之和。这表明，当原始数据函数处于...