Volume 18, Issue 1

The authors describe almost entirely automated procedures for estimation of global, voxel, and cluster-level statistics to test the null hypothesis of zero neuroanatomical difference between two groups of structural magnetic resonance imaging (MRI) data. Theoretical distributions under the null hypothesis are available for (1) global tissue class volumes; (2) standardized linear model [analysis of variance (ANOVA and ANCOVA)] coefficients estimated at each voxel; and (3) an area of spatially connected clusters generated by applying an arbitrary threshold to a two-dimensional (2-D) map of normal statistics at voxel level. The authors describe novel methods for economically ascertaining probability distributions under the null hypothesis, with fewer assumptions, by permutation of the observed data. Nominal Type I error control by permutation testing is generally excellent; whereas theoretical distributions may be over conservative. Permutation has the additional advantage that it can be used to test any statistic of interest, such as the sum of suprathreshold voxel statistics in a cluster (or cluster mass), regardless of its theoretical tractability under the null hypothesis. These issues are illustrated by application to MRI data acquired from 18 adolescents with hyperkinetic disorder and 16 control subjects matched for age and gender.

作者描述了几乎完全自动化的程序，用于估计全局、体素和簇级统计量，以检验两组结构磁共振成像（MRI）数据之间神经解剖学差异为零的零假设。零假设下的理论分布可用于（1）全局组织类别体积；（2）标准化线性模型[分析...

Digital subtraction angiography (DSA) is a well-established modality for the visualization of blood vessels in the human body. A serious disadvantage of this technique, inherent to the subtraction operation, is its sensitivity to patient motion. The resulting artifacts frequently reduce the diagnostic value of the images. Over the past two decades, many solutions to this problem have been put forw...

数字减影血管造影（DSA）是一种用于可视化人体血管的成熟技术。该技术的一个严重缺点是，由于减影操作本身，它对患者运动敏感。由此产生的伪影经常降低图像的诊断价值。在过去的二十年中，针对这一问题提出了许多解决方案...

Advances in visualization technology and specialized graphic workstations allow clinicians to virtually interact with anatomical structures contained within sampled medical-image datasets. A hindrance to the effective use of this technology is the difficult problem of image segmentation. In this paper, the authors utilize a recently proposed oscillator network called the locally excitatory globall...

可视化技术和专业图形工作站的进步使得临床医生能够与采样医学图像数据集中的解剖结构进行虚拟交互。有效利用这一技术的障碍是图像分割这一难题。在本文中，作者利用了一种最近提出的振荡器网络，称为局部兴奋全局...

For noisy X-ray fluoroscopy image sequences the authors quantitatively evaluated image quality after digital temporal filtering to reduce noise. Using an experimental paradigm called a reference/test adaptive forced-choice method the authors compared detectability of stationary low-contrast disks in filtered and un-filtered, computer-generated image sequences. In the first experiment, a low-pass f...

对于噪声较大的X射线透视图像序列，作者通过数字时间滤波来降低噪声，并对其图像质量进行了定量评估。采用一种称为参考/测试自适应强制选择方法的实验范式，作者比较了滤波和未滤波计算机生成图像序列中静止低对比度圆盘的可见性。在第一个实验中，低通滤波...

A variety of inversions of exponential Radon transform has been derived based on the circular harmonic transform in Fourier space by several research groups. However, these inversions cannot be directly applied to deal with the reconstruction for fan-beam or variable-focal-length fan-beam collimator geometries in single photon emission computed tomography (SPECT). In this paper, the authors derive...

多个研究小组基于傅里叶空间中的圆谐波变换推导出了指数Radon变换的各种反演方法。然而，这些反演不能直接应用于单光子发射计算机断层扫描（SPECT）中扇形束或变焦距扇形束准直器几何体的重建。本文作者推导出了一种通用的重建框架...

The authors propose a method that incorporates the time-frequency characteristics of neural sources into magnetoencephalographic (MEG) source estimation. The method is based on the multiple-signal-classification (MUSIC) algorithm and it calculates a time-frequency matrix in which diagonal and off-diagonal terms are the auto and crosstime-frequency distributions of multichannel MEG recordings, resp...

作者提出了一种将神经源的时频特性纳入脑磁图（MEG）源估计的方法。该方法基于多信号分类（MUSIC）算法，计算一个时频矩阵，其中对角项和非对角项分别是多通道MEG记录的自动和交叉时频分布。

Although analyses of in-plane aliasing have been done for conventional computed tomography (CT) images, longitudinal aliasing in spiral CT has not been properly in investigated. The authors propose a mathematical model of the three-dimensional (3-D) sampling scheme in spiral CT and analyze its effects on longitudinal aliasing. They investigated longitudinal aliasing as a function of the helical-in...

尽管传统计算机断层扫描（CT）图像的面内混叠分析已有研究，但螺旋CT中的纵向混叠尚未得到适当研究。作者提出了螺旋CT中三维（3-D）采样方案的数学模型，并分析了其对纵向混叠的影响。他们研究了纵向混叠作为螺旋插值步长的函数...

In previous works, the determination of object and detector scatter kernels from line source measurements was described and their application in scatter correction was investigated. It was also shown that low energy data contains a large fraction of useful events (true and detector scatter events). In the present work, data acquired in multispectral mode was summed in single broad energy windows o...

在以往的工作中，描述了从线源测量中确定物体和探测器散射核的方法，并研究了它们在散射校正中的应用。还表明低能量数据包含大量有用事件（真事件和探测器散射事件）。在本工作中，以多光谱模式获取的数据被求和到单个宽能量窗口...