Volume 18, Issue 9

An algorithm is presented for the fuzzy segmentation of two-dimensional (2-D) and three-dimensional (3-D) multispectral magnetic resonance (MR) images that have been corrupted by intensity inhomogeneities, also known as shading artifacts. The algorithm is an extension of the 2-D adaptive fuzzy C-means algorithm (2-D AFCM) presented in previous work by the authors. This algorithm models the intensity inhomogeneities as a gain field that causes image intensities to smoothly and slowly vary through the image space. It iteratively adapts to the intensity inhomogeneities and is completely automated. In this paper, the authors fully generalize 2-D AFCM to three-dimensional (3-D) multispectral images. Because of the potential size of 3-D image data, they also describe a new faster multigrid-based algorithm for its implementation. They show, using simulated MR data, that 3-D AFCM yields lower error rates than both the standard fuzzy C-means (FCM) algorithm and two other competing methods, when segmenting corrupted images. Its efficacy is further demonstrated using real 3-D scalar and multispectral MR brain images.

提出了一种用于二维和三维多光谱磁共振图像模糊分割的算法，这些图像受到强度不均匀性（也称为阴影伪影）的污染。该算法是作者先前工作中提出的二维自适应模糊C均值算法的扩展。该算法将强度不均匀性建模为一个增益场，导致图像强度在图像空间中平滑且缓慢地变化。它迭代地适应强度不均匀性，并且是完全自动化的。在本文中，作者将二维自适应模糊C均值算法完全推广到三维多光谱图像。由于三维图像数据的潜在大小，他们还描述了一种新的基于多网格的更快算法来实现。他们使用模拟的磁共振数据表明，在分割受污染的图像时，三维自适应模糊C均值算法比标准的模糊C均值算法和其他两种竞争方法具有更低的错误率。使用真实的三维标量和多光谱磁共振脑图像进一步证明了其有效性。

Presents a framework for designing fast and monotonic algorithms for transmission tomography penalized-likelihood image reconstruction. The new algorithms are based on paraboloidal surrogate functions for the log likelihood, Due to the form of the log-likelihood function it is possible to find low curvature surrogate functions that guarantee monotonicity. Unlike previous methods, the proposed surr...

提出了一种用于透射断层扫描惩罚似然图像重建的快速单调算法设计框架。新算法基于对数似然的抛物面替代函数，由于对数似然函数的形式，可以找到保证单调性的低曲率替代函数。与先前方法不同，所提出的替代...

This paper presents a novel speckle suppression method for medical B-scan ultrasonic images. An original image is first separated into two parts with an adaptive filter. These two parts are then transformed into a multiscale wavelet domain and the wavelet coefficients are processed by a soft thresholding method, which is a variation of Donoho's (1995) soft thresholding method. The processed coeffi...

本文提出了一种用于医学B超图像的新型散斑抑制方法。首先通过自适应滤波器将原始图像分为两部分。然后将这两部分变换到多尺度小波域，并采用Donoho（1995）软阈值方法的变体对小波系数进行处理。处理后的系数...

A method is described for the automated detection of microcalcifications in digitized mammograms. The method is based on the Laplacian scale-space representation of the mammogram only. First, possible locations of microcalcifications are identified as local maxima in the filtered image on a range of scales. For each finding, the size and local contrast is estimated, based on the Laplacian response...

描述了一种用于数字化乳腺X线摄影中微钙化自动检测的方法。该方法仅基于乳腺X线摄影的拉普拉斯尺度空间表示。首先，在一系列尺度上，将微钙化的可能位置识别为滤波后图像中的局部最大值。对于每个发现，根据拉普拉斯响应估计其大小和局部对比度...

The aim of the study was to analyze thoracic electrical impedance tomographic (EIT) measurements accomplished under conditions comparable with clinical situations during artificial ventilation. Multiple EIT measurements were performed in pigs in three transverse thoracic planes during the volume controlled mode of mechanical ventilation at various tidal volumes (V/sub T/) and positive end-expirato...

本研究的目的是分析在人工通气期间，在与临床情况相当的条件下进行的胸电阻抗断层成像（EIT）测量。在容量控制机械通气模式下，在不同潮气量（V/sub T/）和呼气末正压条件下，对猪的三个横向胸平面进行了多次EIT测量。

In cone-beam computerized tomography (CT), projections acquired with the focal spot constrained on a planar orbit cannot provide a complete set of data to reconstruct the object function exactly. There are severe distortions in the reconstructed noncentral transverse planes when the cone angle is large. In this work, a new method is proposed which can obtain a complete set of data by acquiring con...

在锥束计算机断层扫描（CT）中，焦点在平面轨道上采集的投影无法提供完整的数据集来精确重建物体函数。当锥角较大时，重建的非中心横向平面存在严重畸变。本文提出了一种新方法，通过采集...

The purpose of this work is to study the architecture of the rearfoot using in vivo MR image data. Each data set used in this study is made of sixty sagittal slices of the foot acquired in a 1.5-T commercial GE MR system. The authors use the live-wire method to delineate boundaries and form the surfaces of the bones. In the first part of this work, they describe a new method to characterize the th...

本研究的目的是利用活体MR图像数据研究后足的结构。本研究中使用的每个数据集均由在1.5-T商用GE MR系统中获取的六十个足部矢状切片组成。作者使用活线法描绘边界并形成骨骼表面。在工作的第一部分，他们描述了一种表征...的新方法。

Methods for reversible coding can be classified according to the organization of the source model as either static, semi-adaptive, or adaptive. Magnetic resonance (MR) images have different statistical characteristics in the foreground and the background and separation is thus a promising path for reversible MR image compression. A new reversible compression method, based on static source models f...

可逆编码的方法可以根据源模型的组织方式分为静态、半自适应或自适应三种。磁共振（MR）图像在前景和背景中具有不同的统计特性，因此分离是进行可逆MR图像压缩的一条有前景的途径。一种基于静态源模型的新可逆压缩方法...