Volume 18, Issue 6

Reconstructing the geometry of the human cerebral cortex from MR images is an important step in both brain mapping and surgical path planning applications. Difficulties with imaging noise, partial volume averaging, image intensity inhomogeneities, convoluted cortical structures, and the requirement to preserve anatomical topology make the development of accurate automated algorithms particularly challenging. Here the authors address each of these problems and describe a systematic method for obtaining a surface representation of the geometric central layer of the human cerebral cortex. Using fuzzy segmentation, an isosurface algorithm, and a deformable surface model, the method reconstructs the entire cortex with the correct topology, including deep convoluted sulci and gyri. The method is largely automated and its results are robust to imaging noise, partial volume averaging, and image intensity inhomogeneities. The performance of this method is demonstrated, both qualitatively and quantitatively, and the results of its application to six subjects and one simulated MR brain volume are presented.

从磁共振图像中重建人脑皮层的几何结构是脑图谱绘制和手术路径规划应用中的重要步骤。成像噪声、部分容积效应、图像强度不均匀性、皮层结构复杂以及保持解剖拓扑结构的要求使得开发精确的自动算法特别具有挑战性。本文作者针对这些问题，描述了一种系统的方法来获取人脑皮层几何中心层的表面表示。该方法结合模糊分割、等值面算法和可变形表面模型，以正确的拓扑结构重建整个皮层，包括深层的复杂脑沟和脑回。该方法大部分是自动化的，其结果对成像噪声、部分容积效应和图像强度不均匀性具有鲁棒性。本文定性和定量地展示了该方法的性能，并给出了应用于六名受试者和一个模拟MR脑体积的结果。

For pt. I see ibid., vol. 18, no. 6, p. 496 (1999). Model-based imaging techniques utilizing microwave signal illumination rely heavily on the ability to accurately represent the wave propagation with a suitable numerical model. To date, the highest quality images from the authors' prototype system have been achieved utilizing a single transmitter/single receiver measurement system where both ante...

第一部分参见同刊第18卷第6期第496页（1999年）。利用微波信号照射的基于模型的成像技术高度依赖于使用合适的数值模型准确表示波传播的能力。迄今为止，作者原型系统获得的高质量图像是通过使用单发射器/单接收器测量系统实现的，其中两个天线...

Examines the use of the algebraic reconstruction technique (ART) and related techniques to reconstruct 3-D objects from a relatively sparse set of cone-beam projections. Although ART has been widely used for cone-beam reconstruction of high-contrast objects, e.g., in computed angiography, the work presented here explores the more challenging low-contrast case which represents a little-investigated...

研究了使用代数重建技术（ART）及相关技术从相对稀疏的锥束投影中重建三维物体。尽管ART已广泛应用于高对比度物体的锥束重建，例如在计算机断层血管造影中，但本文探讨了更具挑战性的低对比度情况，这是一个研究较少的领域。

In magnetic resonance imaging (MRI), the spatial inhomogeneity of the static magnetic field can cause degraded images if the reconstruction is based on inverse Fourier transformation. This paper presents and discusses a range of fast reconstruction algorithms that attempt to avoid such degradation by taking the field inhomogeneity into account. Some of these algorithms are new, others are modified...

在磁共振成像（MRI）中，如果重建基于逆傅里叶变换，静态磁场的空间不均匀性可能导致图像质量下降。本文介绍并讨论了一系列快速重建算法，这些算法通过考虑场不均匀性来避免这种退化。其中一些算法是新的，另一些则是经过改进的...

Fixed-array microwave imaging with multisensor data acquisition can suffer from nonactive antenna element interactions which cause distortions in the measurements. In Part I of a two-part paper, the authors develop a nonactive antenna compensation model for incorporation in model-based near-field microwave image reconstruction methods. The model treats the nonactive members of the antenna array as...

采用多传感器数据采集的固定阵列微波成像可能会受到非活动天线元件相互作用的影响，从而导致测量失真。在一篇分为两部分的论文的第一部分中，作者开发了一种非活动天线补偿模型，用于基于模型的近场微波图像重建方法。该模型将天线阵列中的非活动成员视为...

The prime motivation of this work is to devise techniques that make the algebraic reconstruction technique (ART) and related methods more efficient for routine clinical use, while not compromising their accuracy. Since most of the computational effort of ART is spent for projection/backprojection operations, the authors first seek to optimize the projection algorithm. Existing projection algorithm...

这项工作的主要动机是设计技术，使代数重建技术（ART）及相关方法在日常临床使用中更加高效，同时不降低其准确性。由于ART的大部分计算工作量用于投影/反投影操作，作者首先寻求优化投影算法。现有的投影算法...

Introduces a new model for multiscale analysis of space-time echocardiographic sequences. The proposed nonlinear partial differential equation, representing the multiscale analysis, filters the sequence while keeping the space-time coherent structures. It combines the ideas of regularized Perona-Malik anisotropic diffusion and the Galilean invariant movie multiscale analysis of Alvarez et al. (Arc...

介绍了时空超声心动图序列多尺度分析的一种新模型。所提出的非线性偏微分方程代表了多尺度分析，在滤波序列的同时保持时空相干结构。它结合了正则化Perona-Malik各向异性扩散和Alvarez等人的伽利略不变电影多尺度分析的思想。(Arc...)

A local shape-adaptive template filtering is proposed for the enhancement of the signal-to-noise ratio (SNR) without the loss of resolution in magnetic resonance (MR) imaging. Unlike conventional filtering, where the template shape and coefficients are fixed, multiple templates are defined in the proposed algorithm. An optimal template is selected and optimal filtering, based on the template, is a...

提出了一种局部形状自适应模板滤波方法，用于在磁共振成像中增强信噪比而不损失分辨率。与传统的模板形状和系数固定的滤波不同，该算法定义了多个模板。选择最优模板并基于该模板进行最优滤波，是一种...

Although Close and Whiting found the paper by Meijering el al. (ibid., vol. 18, p. 2-21, 1999) to be both thorough and informative, Close and Whiting feel compelled to correct what they feel to be an inaccurate characterization of their work. Meijering et al. refer to Close and Whitings' 1995 paper ("Motion compensated signal and background estimation from coronary angiograms," in Medical Imaging ...

尽管Close和Whiting认为Meijering等人的论文（同上，第18卷，第2-21页，1999年）既详尽又有信息量，但Close和Whiting感到有必要纠正他们认为对其工作的不准确描述。Meijering等人引用了Close和Whiting 1995年的论文（《从冠状动脉造影图像中运动补偿的信号和背景估计》，载于《医学影像》...）