Volume 29, Issue 4

Statistical shape models are powerful tools for image interpretation and shape analysis. A simple, yet effective, way of building such models is to capture the statistics of sampled point coordinates over a training set of example shapes. However, a major drawback of this approach is the need to establish a correspondence across the training set. In 2-D, a correspondence is often defined using a set of manually placed ¿landmarks¿ and linear interpolation to sample the shape in between. Such annotation is, however, time-consuming and subjective, particularly when extended to 3-D. In this paper, we show that it is possible to establish a dense correspondence across the whole training set automatically by treating correspondence as an optimization problem. The objective function we use for the optimization is based on the minimum description length principle, which we argue is a criterion that leads to models with good compactness, specificity, and generalization ability. We manipulate correspondence by reparameterizing each training shape. We describe an explicit representation of reparameterization for surfaces in 3-D that makes it impossible to generate an illegal (i.e., not one-to-one) correspondence. We also describe several large-scale optimization strategies for model building, and perform a detailed analysis of each approach. Finally, we derive quantitative measures of model quality, allowing meaningful comparison between models built using different methods. Results are given for several different training sets of 3-D shapes, which show that the minimum description length models perform significantly better than other approaches.

统计形状模型是图像解释和形状分析的强大工具。构建此类模型的一种简单而有效的方法是对一组示例形状的训练集中采样点坐标的统计进行捕获。然而，这种方法的一个主要缺点是需要在整个训练集中建立对应关系。在二维中，通常使用一组手动放置的“地标”和线性插值来采样形状之间的对应关系。然而，这种注释耗时且主观，尤其是在扩展到三维时。在本文中，我们证明可以通过将对应关系视为优化问题来自动建立整个训练集的密集对应关系。我们用于优化的目标函数基于最小描述长度原理，我们认为这是导致模型具有良好的紧凑性、特异性和泛化能力的标准。我们通过对每个训练形状进行重新参数化来操纵对应关系。我们描述了一种用于三维表面的重新参数化的显式表示，使得不可能生成非法（即非一一对应）的对应关系。我们还描述了用于模型构建的几种大规模优化策略，并对每种方法进行了详细分析。最后，我们推导出模型质量的定量测量，使得能够对不同方法构建的模型进行有意义的比较。给出了几个不同的三维形状训练集的结果，表明最小描述长度模型明显优于其他方法。

Evaluating rupture risk of abdominal aortic aneurysms is critically important in reducing related mortality without unnecessarily increasing the rate of elective repair. According to the current clinical practice aneurysm rupture risk is (mainly) estimated from its maximum diameter and/or expansion rate; an approach motivated from statistics but known to fail often in individuals. In contrast, rec...

评估腹主动脉瘤破裂风险对于降低相关死亡率而不必要地增加择期修复率至关重要。根据目前的临床实践，动脉瘤破裂风险（主要）通过其最大直径和/或扩张率来估计；这种方法源于统计学，但已知在个体中经常失败。相比之下，重建...

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……

A vital task in the planning of peripheral bronchoscopy is the segmentation of the airway tree from a 3-D multidetector computed tomography chest scan. Unfortunately, existing methods typically do not sufficiently extract the necessary peripheral airways needed to plan a procedure. We present a robust method that draws upon both local and global information. The method begins with a conservative s...

外周支气管镜规划的关键任务之一是从三维多探测器计算机断层扫描胸部扫描中分割气道树。不幸的是，现有方法通常无法充分提取规划过程所需的外周气道。我们提出了一种利用局部和全局信息的鲁棒方法。该方法从保守的...

Reconstruction algorithms for fluorescence tomography have to address two crucial issues: 1) the ill-posedness of the reconstruction problem, 2) the large scale of numerical problems arising from imaging of 3-D samples. Our contribution is the design and implementation of a reconstruction algorithm that incorporates general Lp regularization (p ¿ 1). The originality of this work lies in the applic...

荧光断层成像的重建算法必须解决两个关键问题：1）重建问题的不适定性，2）三维样本成像中产生的大规模数值问题。我们的贡献在于设计和实现了一种包含通用Lp正则化（p ≥ 1）的重建算法。本工作的创新之处在于应用...

Magnetic resonance imaging (MRI) on patients with implanted deep brain stimulators (DBSs) can be hazardous because of the antenna-effect of leads exposed to the incident radio-frequency field. This study evaluated electromagnetic field and specific absorption rate (SAR) changes as a function of lead resistivity on an anatomically precise head model in a 3T system. The anatomical accuracy of our he...

磁共振成像（MRI）对植入深部脑刺激器（DBS）的患者可能存在危险，因为导线暴露于入射射频场会产生天线效应。本研究在3T系统中，使用精确解剖头部模型，评估了电磁场和特定吸收率（SAR）随导线电阻率的变化。我们的解剖精度...

A methodology for estimating the spatial distribution of elastic moduli using the steady-state dynamic response of solids immersed in fluids is presented. The technique relies on the ensuing acoustic field from a remotely excited solid to inversely estimate the spatial distribution of Young's modulus of biological structures (e.g., breast tissue). This work proposes the use of Gaussian radial basi...

提出了一种利用浸没在流体中的固体的稳态动态响应来估算弹性模量空间分布的方法。该技术依赖于远程激励固体产生的声场，以逆估计生物结构（如乳腺组织）的杨氏模量空间分布。本工作建议使用高斯径向基函数...

We advocate a task-based approach to the assessment of image quality using the Bayesian ideal observer. The Bayesian ideal observer provides an absolute upper bound for performance estimates. However, using the full images as inputs to the observer is often infeasible due to their high dimensionality. A practical alternative is to reduce the dimensionality of the images by applying channels, while...

我们倡导一种基于任务的方法，使用贝叶斯理想观察者来评估图像质量。贝叶斯理想观察者提供了一个绝对的上界性能估计。然而，由于图像的高维度，将完整图像作为观察者输入往往不可行。一个实用的替代方案是通过应用通道来降低图像的维度，同时...

Diffusion tensor imaging (DTI) provides important information on the structure of white matter fiber bundles as well as detailed tissue properties along these fiber bundles in vivo. This paper presents a functional regression framework, called FRATS, for the analysis of multiple diffusion properties along fiber bundle as functions in an infinite dimensional space and their association with a set o...

弥散张量成像（DTI）提供了关于白质纤维束结构以及沿这些纤维束的详细组织特性的重要信息。本文提出了一种称为FRATS的功能回归框架，用于分析沿纤维束的多个弥散特性作为无限维空间中的函数及其与一组协变量的关联。

The aim of this paper is to introduce a variational image segmentation method for assessing the aberrant crypt foci (ACF) in the human colon captured in vivo by endoscopy. ACF are thought to be precursors for colorectal cancer, and therefore their early detection may play an important clinical role. We enhance the active contours without edges model of Chan and Vese to account for the ACF's partic...

本文旨在介绍一种变分图像分割方法，用于评估通过内窥镜在体内捕获的人类结肠异常隐窝灶（ACF）。ACF被认为是结直肠癌的前兆，因此其早期检测可能具有重要的临床作用。我们对Chan和Vese的无边缘主动轮廓模型进行了增强，以考虑ACF的特殊性……

In this response letter, technical issues raised by the comments concerning determination of arterial input function, cardiac and respiratory related motion artifacts, contrast agent application, and compartmental model fitting in our work are addressed in detail, and a discussion on identifying causes of uncertainty in physiological measurement and how to minimize their contribution is presented.

在这封回复函中，针对关于我们工作中动脉输入函数测定、心脏和呼吸相关运动伪影、造影剂应用以及房室模型拟合的评论所提出的技术问题进行了详细解答，并讨论了如何识别生理测量不确定性的原因以及如何最小化其贡献。

In our comment some essential issues concerning determination of arterial input function (AIF), cardiac and respiratory related motion artifacts, contrast agent application and compartmental model fitting done by Cao et al., 2009 are discussed.

在我们的评论中，讨论了Cao等人（2009年）在确定动脉输入函数（AIF）、心脏和呼吸相关运动伪影、对比剂应用以及房室模型拟合方面的一些重要问题。

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