Volume 18, Issue 12

Conventional model-based or statistical analysis methods for functional MRI (fMRI) suffer from the limitation of the assumed paradigm and biased results. Temporal clustering methods, such as fuzzy clustering, can eliminate these problems but are difficult to find activation occupying a small area, sensitive to noise and initial values, and computationally demanding. To overcome these adversities, a cascade clustering method combining a Kohonen clustering network and fuzzy c means is developed. Receiver operating characteristic (ROC) analysis is used to compare this method with correlation coefficient analysis and t test on a series of testing phantoms. Results show that this method can efficiently and stably identify the actual functional response with typical signal change to noise ratio, from a small activation area occupying only 0.2% of head size, with phase delay, and from other noise sources such as head motion. With the ability of finding activities of small sizes stably, this method can not only identify the functional responses and the active regions more precisely, but also discriminate responses from different signal sources, such as large venous vessels or different types of activation patterns in human studies involving motor cortex activation. Even when the experimental paradigm is unknown in a blind test such that model-based methods are inapplicable, this method can identify the activation patterns and regions correctly.

传统的基于模型或统计分析方法用于功能磁共振成像（fMRI）受限于假设的范式和有偏的结果。时间聚类方法，如模糊聚类，可以消除这些问题，但难以找到占据小区域的激活，对噪声和初始值敏感，且计算量大。为了克服这些困难，开发了一种结合Kohonen聚类网络和模糊C均值的级联聚类方法。使用受试者工作特征（ROC）分析将该方法与相关系数分析和t检验在一系列测试体模上进行比较。结果表明，该方法能够高效且稳定地识别实际的功能响应，即使激活区域仅占头部大小的0.2%，存在相位延迟，以及来自头部运动等其他噪声源，且具有典型的信噪比。凭借稳定发现小尺寸活动的能力，该方法不仅能更精确地识别功能响应和激活区域，还能区分来自不同信号源的响应，如大静脉血管或涉及运动皮层激活的人类研究中的不同激活模式。即使在盲测试中实验范式未知，使得基于模型的方法无法适用时，该方法也能正确识别激活模式和区域。

In this article, multiresolution analysis, specifically the discrete wavelet transform modulus-maxima (mod-max) method, is utilized for the extraction of mammographic mass shape features. These shape features are used in a classification system to classify masses as round, nodular, or stellate. The multiresolution shape features are compared with traditional uniresolution shape features for their ...

本文采用多分辨率分析，特别是离散小波变换模极大值（mod-max）方法，用于提取乳腺肿块形状特征。这些形状特征用于分类系统，将肿块分为圆形、结节状或星状。将多分辨率形状特征与传统的单分辨率形状特征进行比较...

A new type of classifier combining an unsupervised and a supervised model was designed and applied to classification of malignant and benign masses on mammograms. The unsupervised model was based on an adaptive resonance theory (ART2) network which clustered the masses into a number of separate classes. The classes were divided into two types: one containing only malignant masses and the other con...

设计了一种结合无监督模型和有监督模型的新型分类器，并将其应用于乳腺X线图像中恶性与良性肿块的分类。无监督模型基于自适应共振理论（ART2）网络，将肿块聚类为若干独立类别。这些类别被分为两类：一类仅包含恶性肿块，另一类仅包含良性肿块。

The maximum intensity projection (MIP) is a popularly used algorithm for display of MRA images, but its performance has not been rigorously analyzed before. In this paper, four measures are proposed for the performance of the MIP algorithm and the quality of images projected from three-dimensional (3-D) data, which are vessel voxel projection probability, vessel detection probability, false vessel...

最大强度投影（MIP）是一种广泛用于显示MRA图像的算法，但其性能此前尚未得到严格分析。本文提出了四个指标来评估MIP算法的性能以及从三维（3-D）数据投影的图像质量，这些指标包括血管体素投影概率、血管检测概率、假血管...

The methods of Bayesian statistics are applied to the analysis of fMRI data, Three specific models are examined. The first is the familiar linear model with white Gaussian noise. In this section, the Jeffreys' Rule for noninformative prior distributions is stated and it is shown how the posterior distribution may be used to infer activation in individual pixels. Next, linear time-invariant (LTI) s...

贝叶斯统计方法应用于fMRI数据分析。考察了三个特定模型。第一个是带有白高斯噪声的常见线性模型。在这一部分，介绍了无信息先验分布的杰弗里斯规则，并展示了如何使用后验分布来推断单个像素的激活。接下来，线性时不变（LTI）...

Extends basic concepts of statistical hypothesis testing and confidence intervals to images generated by a new procedure for near infrared spectroscopic tomography being developed for use in breast cancer diagnosis. By estimating the covariance matrix of the pixels of an image from data used in the image reconstruction process, confidence maps for statistical tests on individual pixels and confide...

将统计假设检验和置信区间的基本概念扩展到一种新型近红外光谱断层成像程序所生成的图像，该程序正被开发用于乳腺癌诊断。通过从图像重建过程中使用的数据估计图像像素的协方差矩阵，可以对单个像素进行统计检验的置信图以及...

A new approach for analysis of RF coils in magnetic resonance (MR) experiments is reported. Instead of assuming current distribution in conventional quasi-static algorithm, this approach transforms the coil geometry into an equivalent circuit for complex current calculation. Self and mutual inductance are taken into consideration. Frequency responses of RF coils and transverse magnetic field (B/su...

报告了一种用于磁共振实验中的射频线圈分析的新方法。该方法不采用传统准静态算法中假设电流分布的方式，而是将线圈几何结构转化为等效电路以进行复杂电流计算。考虑了自感和互感。射频线圈的频率响应和横向磁场...

The authors have developed a simple method for determining coincidence attenuation-correction factors C (the inverse of the total attenuation factors) from collimated singles (SPECT) and coincidence [positron emission tomography (PET)] projections without transmission data. Attenuation-correction factor estimates are determined for individual lines of response (LOR's) independently. The required d...

作者开发了一种简单的方法，用于从准直单光（SPECT）和符合[正电子发射断层扫描（PET）]投影中确定符合衰减校正因子C（总衰减因子的倒数），而无需透射数据。衰减校正因子估计是针对每条响应线（LOR）独立确定的。所需的...

This index covers all technical items - papers, correspondence, reviews, etc. - that appeared in this periodical during the year, and items from previous years that were commented upon or corrected in this year. Departments and other items may also be covered if they have been judged to have archival value. The Author Index contains the primary entry for each item, listed under the first author's ...

本索引涵盖本年度该期刊中的所有技术项目——论文、通讯、评论等，以及往年在本年度被评论或更正的项目。如果部门和其他项目被认为具有存档价值，也可能被收录。作者索引包含每个项目的条目，列在第一作者名下。

This index covers all technical items - papers, correspondence, reviews, etc. - that appeared in this periodical during the year, and items from previous years that were commented upon or corrected in this year. Departments and other items may also be covered if they have been judged to have archival value. The Author Index contains the primary entry for each item, listed under the first author's ...

本索引涵盖了本年度在该期刊上出现的所有技术项目——论文、通信、评论等，以及前些年在本年度被评论或更正的项目。部门和其他项目如果被认为具有档案价值也会被收录。作者索引包含每个项目的主要条目，列在第一作者名下……