Volume 21, Issue 8

An active shape model segmentation scheme is presented that is steered by optimal local features, contrary to normalized first order derivative profiles, as in the original formulation [Cootes and Taylor, 1995, 1999, and 2001]. A nonlinear kNN-classifier is used, instead of the linear Mahalanobis distance, to find optimal displacements for landmarks. For each of the landmarks that describe the shape, at each resolution level taken into account during the segmentation optimization procedure, a distinct set of optimal features is determined. The selection of features is automatic, using the training images and sequential feature forward and backward selection. The new approach is tested on synthetic data and in four medical segmentation tasks: segmenting the right and left lung fields in a database of 230 chest radiographs, and segmenting the cerebellum and corpus callosum in a database of 90 slices from MRI brain images. In all cases, the new method produces significantly better results in terms of an overlap error measure (p<0.001 using a paired T-test) than the original active shape model scheme.

提出了一种由最优局部特征引导的主动形状模型分割方案，与原始公式（Cootes和Taylor，1995、1999和2001）中使用的归一化一阶导数轮廓相反。使用非线性kNN分类器代替线性马氏距离来寻找地标的最优位移。对于描述形状的每个地标，在分割优化过程中考虑的每个分辨率级别上，确定一组不同的最优特征。特征是自动选择的，利用训练图像和顺序特征前向和后向选择。新方法在合成数据和四个医学分割任务中进行了测试：在230张胸部X光片数据库中分割左右肺野，以及在90张MRI脑图像切片数据库中分割小脑和胼胝体。在所有情况下，新方法在重叠误差度量方面（配对T检验p<0.001）比原始主动形状模型方案产生显著更好的结果。

Automatic three-dimensional (3-D) segmentation of the brain from magnetic resonance (MR) scans is a challenging problem that has received an enormous amount of attention lately. Of the techniques reported in the literature, very few are fully automatic. In this paper, we present an efficient and accurate, fully automatic 3-D segmentation procedure for brain MR scans. It has several salient feature...

自动三维（3-D）脑部磁共振（MR）扫描分割是一个具有挑战性的问题，最近受到了极大关注。在文献报道的技术中，很少有完全自动化的。在本文中，我们提出了一种高效、准确的完全自动三维脑部MR扫描分割程序。它具有几个显著特征...

Quantitative accuracy of single photon emission computed tomography (SPECT) images is highly dependent on the photon scatter model used for image reconstruction. Monte Carlo simulation (MCS) is the most general method for detailed modeling of scatter, but to date, fully three-dimensional (3-D) MCS-based statistical SPECT reconstruction approaches have not been realized, due to prohibitively long c...

单光子发射计算机断层扫描（SPECT）图像的定量准确性高度依赖于图像重建中使用的光子散射模型。蒙特卡罗模拟（MCS）是详细建模散射的最通用方法，但迄今为止，由于计算时间过长，尚未实现基于全三维（3-D）MCS的统计SPECT重建方法...

This paper describes phase maps. A review of the phase unwrapping problem is given. Different structures, in particular fringelines, cutlines, and poles, contained within a phase map are described and their origin and behavior investigated. The problem of phase unwrapping can then be addressed with a better understanding of the source of poles or inconsistencies. This understanding, along with som...

本文描述了相位图。回顾了相位展开问题。描述了相位图中包含的不同结构，特别是条纹线、切割线和极点，并研究了它们的起源和行为。通过更好地理解极点或不一致性的来源，可以解决相位展开问题。这种理解，再加上一些...

Computer-aided surgery (CAS), the intraoperative application of biomedical visualization techniques, appears to be one of the most promising fields of application for augmented reality (AR), the display of additional computer-generated graphics over a real-world scene. Typically a device such as a head-mounted display (HMD) is used for AR. However, considerable technical problems connected with AR...

计算机辅助手术（CAS）是生物医学可视化技术的术中应用，似乎是最有前途的增强现实（AR）应用领域之一，即在真实场景上显示额外的计算机生成图形。通常，诸如头戴式显示器（HMD）之类的设备用于增强现实。然而，与增强现实相关的技术问题相当大...

Pinhole collimators are widely used to image small organs and animals. The pinhole response function (PRF) of knife-edge pinhole collimators has been estimated previously using geometric constructions without considering penetration and using &#34;roll-off&#34; models that employ an exponential model for the flux. An analytic expression for the PRF on the imaging plane that includes the effect of aperture...

针孔准直器广泛用于成像小器官和动物。之前，刀边针孔准直器的针孔响应函数（PRF）是通过不考虑穿透的几何构造和使用指数通量模型的“滚降”模型来估计的。本文给出了成像平面上包含孔径效应的PRF的解析表达式。

Previous work has suggested the existence of differences between the cerebral cortex of normal individuals, and those of patients with diseases such as epilepsy and schizophrenia. These shape abnormalities may be of developmental origin. Improved shape measures could provide useful tools for neuroscience research and patient diagnosis. We consider the theoretically desirable properties of measures...

以往的研究表明，正常个体与患有癫痫和精神分裂症等疾病的患者的大脑皮层之间存在差异。这些形状异常可能源于发育过程。改进的形状测量可以为神经科学研究和患者诊断提供有用的工具。我们考虑了测量的理论期望特性...

Active model-based segmentation has frequently been used in medical image processing with considerable success. Although the active model-based method was initially viewed as an optimization problem, most researchers implement it as a partial differential equation solution. The advantages and disadvantages of the active model-based method are distinct: speed and stability. To improve its performan...

基于活动模型的图像分割在医学图像处理中经常被使用，并取得了相当大的成功。尽管基于活动模型的方法最初被视为优化问题，但大多数研究人员将其实现为偏微分方程解。基于活动模型的方法的优缺点很明显：速度和稳定性。为了提高其性能...

This paper presents a fully automated segmentation method for medical images. The goal is to localize and parameterize a variety of types of structure in these images for subsequent quantitative analysis. We propose a new hybrid strategy that combines a general elastic template matching approach and an evolutionary heuristic. The evolutionary algorithm uses prior statistical information about the ...

本文提出了一种全自动的医学图像分割方法。目标是在这些图像中定位并参数化多种类型的结构，以便进行后续的定量分析。我们提出了一种新的混合策略，该策略结合了通用弹性模板匹配方法和进化启发式算法。进化算法使用关于...的先验统计信息

Though fluid dynamics offer a good approach to nonrigid registration and give accurate results, even with large-scale deformations, its application is still very time consuming. We introduce and discuss different approaches to solve the core problem of nonrigid registration, the partial differential equation of fluid dynamics. We focus on the solvers, their computational costs and the accuracy of ...

尽管流体动力学为非刚性配准提供了良好的方法，并且即使在较大变形的情况下也能获得准确的结果，但其应用仍然非常耗时。我们介绍并讨论了解决非刚性配准核心问题（流体动力学的偏微分方程）的不同方法。我们重点讨论了求解器、它们的计算成本以及精度……

This paper describes a new method of combining ray-casting with segmentation. Volume rendering is performed at interactive rates on personal computers, and visualizations include both &#34;superficial&#34; ray-casting through a shell at each object's surface and &#34;deep&#34; ray-casting through the confines of each object. A feature of the approach is the option to smoothly and interactively dilate segmentation...

本文描述了一种将光线投射与分割相结合的新方法。在个人计算机上以交互速率进行体渲染，可视化包括通过每个物体表面的壳进行的“浅层”光线投射和通过每个物体边界进行的“深层”光线投射。该方法的一个特点是能够平滑且交互地扩张分割...

The utility of optical tomography as a practical imaging modality has, thus far, been limited by its intrinsically low spatial resolution and quantitative accuracy. Recently, we have argued that a broad range of physiological phenomena might be accurately studied by adopting this technology to investigate dynamic states (Schmitz et al., 2000; Barbour et al., 2000; Graber et al., 2000; Barbour et a...

迄今为止，光学断层成像作为一种实用成像方式的效用受到其固有低空间分辨率和定量准确性的限制。最近，我们认为，通过采用这种技术研究动态状态，可以准确研究广泛的生理现象（Schmitz等人，2000；Barbour等人，2000；Graber等人，2000；Barbour等人...）

We developed a new triangulated deformable surface model, which is used to detect the boundary of the bones in three-dimensional magnetic resonance (MR) and computed tomography (CT) images of the wrist. This surface model is robust to initialization and provides wide geometrical coverage and quantitative power. The surface is deformed by applying one-dimensional (1-D) radial Lagrangian dynamics. F...

我们开发了一种新的三角化可变形表面模型，用于检测手腕三维磁共振（MR）和计算机断层扫描（CT）图像中骨骼的边界。该表面模型对初始化具有鲁棒性，提供广泛的几何覆盖和定量能力。表面通过应用一维（1-D）径向拉格朗日动力学进行变形。...

Spatially variant longitudinal aliasing plagues most volumes reconstructed from single-slice helical computed tomography data, and its presence can degrade resolution and distort image structures. We have recently developed a Fourier-based approach to longitudinal interpolation in helical computed tomography that can, for scans performed at pitch 1 or lower, essentially eliminate this longitudinal...

空间变化的纵向混叠困扰着大多数从单层螺旋计算机断层扫描数据重建的体积，其存在会降低分辨率并扭曲图像结构。我们最近开发了一种基于傅里叶的螺旋CT纵向插值方法，对于在螺距1或更低条件下进行的扫描，可以基本消除这种纵向混叠...