Volume 23, Issue 8

A primary goal of statistical shape analysis is to describe the variability of a population of geometric objects. A standard technique for computing such descriptions is principal component analysis. However, principal component analysis is limited in that it only works for data lying in a Euclidean vector space. While this is certainly sufficient for geometric models that are parameterized by a set of landmarks or a dense collection of boundary points, it does not handle more complex representations of shape. We have been developing representations of geometry based on the medial axis description or m-rep. While the medial representation provides a rich language for variability in terms of bending, twisting, and widening, the medial parameters are not elements of a Euclidean vector space. They are in fact elements of a nonlinear Riemannian symmetric space. In this paper, we develop the method of principal geodesic analysis, a generalization of principal component analysis to the manifold setting. We demonstrate its use in describing the variability of medially-defined anatomical objects. Results of applying this framework on a population of hippocampi in a schizophrenia study are presented.

统计形状分析的一个主要目标是描述几何对象群体的变异性。标准技术是主成分分析。但主成分分析仅适用于欧几里得向量空间中的数据。对于由一组标志点或密集边界点参数化的几何模型，这足够，但不处理更复杂的形状表示。我们基于中轴描述（m-rep）开发了几何表示。中轴表示提供了弯曲、扭转、加宽等变异性丰富语言，但中轴参数不是欧几里得向量空间的元素，而是非线性黎曼对称空间的元素。本文发展了主测地线分析方法，将主成分分析推广到流形设置。我们展示了其在描述中轴定义的解剖对象变异性中的应用。在精神分裂症研究中，将该框架应用于海马群体的结果展示。

We developed a general method for global conformal parameterizations based on the structure of the cohomology group of holomorphic one-forms for surfaces with or without boundaries (Gu and Yau, 2002), (Gu and Yau, 2003). For genus zero surfaces, our algorithm can find a unique mapping between any two genus zero manifolds by minimizing the harmonic energy of the map. In this paper, we apply the alg...

我们基于有界或无界曲面的全纯一次微分形式的同调群结构，发展了一种全局共形参数化的通用方法（Gu and Yau, 2002; Gu and Yau, 2003）。对于零亏格曲面，我们的算法可以通过最小化映射的调和能量，在任意两个零亏格流形之间找到唯一映射。在本文中，我们将该算法应用于...

It is well known in the pattern recognition community that the accuracy of classifications obtained by combining decisions made by independent classifiers can be substantially higher than the accuracy of the individual classifiers. We have previously shown this to be true for atlas-based segmentation of biomedical images. The conventional method for combining individual classifiers weights each cl...

在模式识别领域，众所周知，通过组合独立分类器的决策所获得的分类准确率可以显著高于单个分类器的准确率。我们之前已经证明，这一点对于基于图谱的生物医学图像分割同样成立。组合单个分类器的传统方法是对每个分类器进行加权...

In this paper, we present a novel constrained variational principle for simultaneous smoothing and estimation of the diffusion tensor field from complex valued diffusion-weighted images (DWI). The constrained variational principle involves the minimization of a regularization term of L/sup p/ norms, subject to a nonlinear inequality constraint on the data. The data term we employ is the original S...

本文提出了一种新颖的约束变分原理，用于从复值扩散加权图像（DWI）同时平滑和估计扩散张量场。

Most of the approaches dedicated to automatic morphometry rely on a point-by-point strategy based on warping each brain toward a reference coordinate system. In this paper, we describe an alternative object-based strategy dedicated to the cortex. This strategy relies on an artificial neuroanatomist performing automatic recognition of the main cortical sulci and parcellation of the cortical surface...

大多数自动形态测量方法依赖于基于逐点策略的每个大脑向参考坐标系的扭曲。本文描述了一种专门针对皮层基于对象的替代策略。该策略依赖于一个执行主要皮层沟自动识别和皮层表面分区的人工神经解剖学家。

Respiratory motion compensation for cardiac imaging requires knowledge of the heart's motion and deformation during breathing. This paper presents a method for measuring the natural tidal respiratory motion of the heart from free breathing coronary angiograms. A three-dimensional (3-D) deformation field describing the cardiac and respiratory motion of the coronary arteries is recovered from a bipl...

心脏成像的呼吸运动补偿需要了解呼吸过程中心脏的运动和变形。本文提出了一种从自由呼吸冠状动脉造影中测量心脏自然潮气呼吸运动的方法。从双平面...恢复出描述冠状动脉心脏和呼吸运动的三维变形场。

A novel method for the segmentation of multiple objects from three-dimensional (3-D) medical images using interobject constraints is presented. Our method is motivated by the observation that neighboring structures have consistent locations and shapes that provide configurations and context that aid in segmentation. We define a maximum a posteriori (MAP) estimation framework using the constraining...

提出了一种利用物体间约束从三维（3D）医学图像中分割多个物体的新方法。我们的方法受到以下观察的启发：相邻结构具有一致的位置和形状，这些位置和形状提供了有助于分割的配置和背景。我们定义了一个最大后验（MAP）估计框架，使用约束...

Groupwise nonrigid registrations of medical images define dense correspondences across a set of images, defined by a continuous deformation field that relates each target image in the group to some reference image. These registrations can be automatic, or based on the interpolation of a set of user-defined landmarks, but in both cases, quantifying the normal and abnormal structural variation acros...

医学图像的群体非刚性配准定义了一组图像之间的密集对应关系，该对应关系由连续形变场定义，该形变场将组中的每个目标图像与某个参考图像相关联。这些配准可以是自动的，也可以基于一组用户定义地标的插值，但在这两种情况下，量化正常和异常结构变异...

Virtual bronchoscopy reconstructions of the airway noninvasively provide useful morphologic information of structural abnormalities such as stenoses and masses. In this paper, we show how virtual bronchoscopy can be used to perform aerodynamic calculations in anatomically realistic models. Pressure and flow patterns in a human airway were computed noninvasively. These showed decreased pressure and...

虚拟支气管镜重建气道无创地提供结构异常如狭窄和肿块的有用形态学信息。在本文中，我们展示了如何利用虚拟支气管镜在解剖学真实模型中进行空气动力学计算。无创地计算了人类气道中的压力和流动模式。这些结果显示压力降低和...

A convenient way to analyze blood-oxygen-level-dependent functional magnetic resonance imaging data consists of modeling the whole brain as a stationary, linear system characterized by its transfer function: the hemodynamic response function (HRF). HRF estimation, though of the greatest interest, is still under investigation, for the problem is ill-conditioned. In this paper, we recall the most ge...

分析血氧水平依赖功能磁共振成像数据的一种便捷方法是，将整个大脑建模为一个稳态线性系统，其特征通过传递函数即血流动力学响应函数（HRF）来描述。HRF估计尽管备受关注，但由于问题条件不佳，仍在研究中。本文回顾了最通用的...

A technique has been developed for combining a series of low signal-to-noise ratio (SNR) real-time magnetic resonance (MR) images to produce composite images with high SNR and minimal artifact in the presence of motion. The main challenge is identifying a set of real-time images with sufficiently small systematic differences to avoid introducing significant artifact into the composite image. To ac...

开发了一种技术，用于结合一系列低信噪比（SNR）实时磁共振（MR）图像，以生成具有高信噪比且在运动情况下伪影最小的复合图像。主要挑战是识别一组系统差异足够小的实时图像，以避免在复合图像中引入显著伪影。为了...

Provides a listing of current committee members and society officers.

提供当前委员会成员和学会官员的列表。

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此页或这些页故意留空。

Presents the table of contents for this issue of the periodical.

呈现本期期刊的目录。

Provides instructions and guidelines to prospective authors who wish to submit manuscripts.

为希望提交手稿的潜在作者提供指导和指南。