Volume 18, Issue 4

The authors examine the spatial resolution and variance properties of PET images reconstructed using maximum a posteriori (MAP) or penalized-likelihood methods. Resolution is characterized by the contrast recovery coefficient (CRC) of the local impulse response. Simplified approximate expressions are derived for the local impulse response CRCs and variances for each voxel. Using these results the authors propose a practical scheme for selecting spatially variant smoothing parameters to optimize lesion detectability through maximization of the local CRC-to-noise ratio in the reconstructed image.

作者研究了使用最大后验（MAP）或惩罚似然方法重建的PET图像的空间分辨率和方差特性。分辨率通过局部脉冲响应的对比度恢复系数（CRC）来表征。推导了每个体素的局部脉冲响应CRC和方差的简化近似表达式。利用这些结果，作者提出了一种实用的方案，通过最大化重建图像中的局部CRC与噪声比，来选择空间变化的平滑参数以优化病灶可检测性。

Images captured with a typical endoscope show spatial distortion, which necessitates distortion correction for subsequent analysis. Here, a new methodology based on least squares estimation is proposed to correct the nonlinear distortion in the endoscopic images. A mathematical model based on polynomial mapping is used to map the images from distorted image space onto the corrected image space. Th...

使用典型内窥镜捕获的图像存在空间畸变，这需要畸变校正以便后续分析。本文提出了一种基于最小二乘估计的新方法来校正内窥镜图像中的非线性畸变。采用基于多项式映射的数学模型将图像从畸变图像空间映射到校正后的图像空间。

Presents a validation study of an optical-flow method for the rapid estimation of myocardial displacement in magnetic resonance tagged cardiac images. This registration and change visualization (RCV) software uses a hierarchical estimation technique to compute the flow field that describes the warping of an image of one cardiac phase into alignment with the next. This method overcomes the requirem...

介绍了一种用于快速估计磁共振标记心脏图像中心肌位移的光流方法的验证研究。该配准与变化可视化（RCV）软件使用分层估计技术来计算描述一个心脏相位图像变形以与下一个相位对齐的光流场。该方法克服了需要...

The majority of functional magnetic resonance imaging (fMRI) studies obtain functional information using statistical tests based on the magnitude image reconstructions. Recently, a complex correlation (CC) test was proposed based on the complex image data in order to take advantage of phase information in the signal. However, the CC test ignores additional phase information in the baseline compone...

大多数功能磁共振成像（fMRI）研究使用基于幅度图像重建的统计检验来获取功能信息。最近，提出了基于复数图像数据的复数相关（CC）测试，以利用信号中的相位信息。然而，CC测试忽略了基线分量中的额外相位信息...

This paper addresses the problem of neuro-anatomical registration across individuals for functional [/sup 15/O] water PET activation studies. A new algorithm for three-dimensional (3-D) nonlinear structural registration (warping) of MR scans is presented. The method performs a hierarchically scaled search for a displacement field, maximizing one of several voxel similarity measures derived from th...

本文讨论了功能性[15O]水PET激活研究中个体间神经解剖配准的问题。提出了一种新的三维非线性结构配准（扭曲）MR扫描的算法。该方法通过分层尺度搜索位移场，最大化从几个体素相似度度量中导出的...

Magnetic resonance (MR) tagging has been shown to be a useful technique for noninvasively measuring the deformation of an in vivo heart. An important step in analyzing tagged images is the identification of tag lines in each image of a cine sequence. Most existing tag identification algorithms require user defined myocardial contours. Contour identification, however, is time consuming and requires...

磁共振（MR）标记已被证明是一种非侵入性测量活体心脏变形的有用技术。分析标记图像的一个重要步骤是识别电影序列中每幅图像中的标记线。大多数现有的标记识别算法需要用户定义的心肌轮廓。然而，轮廓识别耗时且需要...

In recent years, the use of computer graphic techniques to produce three-dimensional (3-D) and reformatted images from a set of axial computed tomography (CT) images has gained significant interest. In most cases, the CT images are generated with the projection data set weighted prior to reconstruction, to combat motion artifacts, data inconsistency, or redundant data samples. Here, the author inv...

近年来，使用计算机图形技术从一组轴向计算机断层扫描（CT）图像生成三维（3-D）和重组图像引起了极大兴趣。在大多数情况下，通过重建前对投影数据集进行加权来生成CT图像，以对抗运动伪影、数据不一致或冗余数据样本。这里，作者引入...

The authors investigated the use of the kinestatic charge detector (KCD) combined with the multilevel scheme algebraic reconstruction technique (MLS-ART) for X-ray computer tomography (CT) reconstruction. The KCD offers excellent detective quantum efficiency and contrast resolution. These characteristics are especially helpful for applications in which a limited number of projections are used. In ...

作者研究了使用动态电荷探测器(KCD)结合多级代数重建技术(MLS-ART)进行X射线计算机断层扫描(CT)重建。KCD具有出色的探测量子效率和对比度分辨率。这些特性对于使用有限数量投影的应用尤其有帮助。在...