Volume 22, Issue 4

There have been significant efforts to build a probabilistic atlas of the brain and to use it for many common applications, such as segmentation and registration. Though the work related to brain atlases can be applied to nonbrain organs, less attention has been paid to actually building an atlas for organs other than the brain. Motivated by the automatic identification of normal organs for applications in radiation therapy treatment planning, we present a method to construct a probabilistic atlas of an abdomen consisting of four organs (i.e., liver, kidneys, and spinal cord). Using 32 noncontrast abdominal computed tomography (CT) scans, 31 were mapped onto one individual scan using thin plate spline as the warping transform and mutual information (MI) as the similarity measure. Except for an initial coarse placement of four control points by the operators, the MI-based registration was automatic. Additionally, the four organs in each of the 32 CT data sets were manually segmented. The manual segmentations were warped onto the "standard" patient space using the same transform computed from their gray scale CT data set and a probabilistic atlas was calculated. Then, the atlas was used to aid the segmentation of low-contrast organs in an additional 20 CT data sets not included in the atlas. By incorporating the atlas information into the Bayesian framework, segmentation results clearly showed improvements over a standard unsupervised segmentation method.

在构建脑部概率图谱并将其用于分割和配准等常见应用方面已经做出了巨大努力。尽管与脑图谱相关的工作可以应用于非脑器官，但实际为脑以外的器官构建图谱的研究较少。受放射治疗计划中正常器官自动识别的启发，我们提出了一种构建腹部概率图谱的方法，该图谱包含四个器官（即肝脏、肾脏和脊髓）。使用32次非增强腹部计算机断层扫描（CT），通过薄板样条作为变形变换，互信息（MI）作为相似性度量，将31次扫描映射到单个个体扫描上。除了操作员初始粗略放置四个控制点外，基于MI的配准是自动的。此外，对32个CT数据集中的每个数据集中的四个器官进行了手动分割。使用从其灰度CT数据集计算出的相同变换将手动分割结果变形到“标准”患者空间，并计算概率图谱。然后，该图谱用于辅助分割未包含在图谱中的另外20个CT数据集中对比度低的器官。通过将图谱信息融入贝叶斯框架，分割结果明显优于标准的无监督分割方法。

Presents a statistical shape model for the automatic prostate segmentation in transrectal ultrasound images. A Gabor filter bank is first used to characterize the prostate boundaries in ultrasound images in both multiple scales and multiple orientations. The Gabor features are further reconstructed to be invariant to the rotation of the ultrasound probe and incorporated in the prostate model as im...

提出了一种用于经直肠超声图像中自动分割前列腺的统计形状模型。首先使用Gabor滤波器组在多个尺度和多个方向上表征超声图像中的前列腺边界。进一步重构Gabor特征使其对超声探头的旋转不变，并将其纳入前列腺模型作为im...

A new method to increase the signal-to-noise ratio (SNR) of synthetic transmit aperture imaging is investigated. The approach utilizes multiple elements to emulate a spherical wave, and the conventional short excitation pulse is replaced by a linear frequency-modulated (FM) signal. The approach is evaluated in terms of image quality parameters in comparison to linear array imaging. Field II simula...

研究了一种提高合成发射孔径成像信噪比的新方法。该方法利用多个元素模拟球面波，并用线性调频信号替代传统的短激励脉冲。通过与线性阵列成像比较，评估了该方法的图像质量参数。Field II模拟...

A three-dimensional (3-D) method for tracking the coronary arteries through a temporal sequence of biplane X-ray angiography images is presented. A 3-D centerline model of the coronary vasculature is reconstructed from a biplane image pair at one time frame, and its motion is tracked using a coarse-to-fine hierarchy of motion models. Three-dimensional constraints on the length of the arteries and ...

提出了一种通过双平面X射线血管造影图像时间序列跟踪冠状动脉的三维（3-D）方法。在单个时间帧从双平面图像对重建冠状动脉血管系统的三维中心线模型，并使用从粗到细的运动模型层次跟踪其运动。三维约束作用于动脉长度和......

In this study, we registered live-time interventional magnetic resonance imaging (iMRI) slices with a previously obtained high-resolution MRI volume that in turn can be registered with a variety of functional images, e.g., PET, SPECT, for tumor targeting. We created and evaluated a slice-to-volume (SV) registration algorithm with special features for its potential use in iMRI-guided radio-frequenc...

在本研究中，我们将实时介入磁共振成像（iMRI）切片与先前获得的高分辨率MRI体积进行配准，而该体积又可以与各种功能图像（例如PET、SPECT）进行配准，以用于肿瘤靶向。我们创建并评估了一种切片到体积（SV）配准算法，该算法具有特殊特征，可用于iMRI引导的射频热消融治疗。

We set out a new general framework for making inferences from neuroimaging data, which includes a standard approach to neuroimaging analysis, statistical parametric mapping (SPM), as a special case. The model offers numerous conceptual and statistical advantages that derive from analyzing data at the "cluster level" rather than the "voxel level" and from explicit modeling of the shape and position...

我们提出了一个新的通用框架，用于从神经影像数据中进行推断，该框架将标准的神经影像分析方法——统计参数映射（SPM）作为特例。该模型提供了众多概念和统计上的优势，这些优势源于在“簇水平”而非“体素水平”分析数据，以及对形状和位置进行显式建模...

This paper reports the results of a complete circumferential scan of a human tooth and its underlying dentino-enamel junction using ultrasound at frequencies in the 10-MHz range. The imagery shows clearly a two-dimensional contour of the dentino-enamel junction with a depth and lateral resolution of approximately 100 /spl mu/m and 750 /spl mu/m, respectively. The resulting sonograph is compared wi...

本文报道了使用10 MHz频率范围内的超声波对人体牙齿及其下方的牙本质-釉质连接处进行完整圆周扫描的结果。图像清晰地显示了牙本质-釉质连接的二维轮廓，深度分辨率约为100微米，横向分辨率约为750微米。生成的声像图与...进行比较。

Several strategies, known as clutter or wall Doppler filtering, were proposed to remove the strong echoes produced by stationary or slow moving tissue structures from the Doppler blood flow signal. In this study, the matching pursuit (MP) method is proposed to remove clutter components. The MP method decomposes the Doppler signal into wavelet atoms that are selected in a decreasing energy order. T...

已经提出了几种策略，称为杂波或壁多普勒滤波，以从多普勒血流信号中去除静止或缓慢移动的组织结构产生的强回声。在本研究中，提出了匹配追踪（MP）方法来去除杂波成分。MP方法将多普勒信号分解为小波原子，这些原子按能量递减顺序选择。

A modified optimization-based contour detection method was presented to compute the lumen area of the coronary artery from intravascular ultrasound (IVUS) video images. First, the search range for the artery inner wall was determined based on the continuity of IVUS video frames. Next, the internal and external energy were calculated to describe the smoothness of the arterial wall and the grayscale...

提出了一种改进的基于优化的轮廓检测方法，用于从血管内超声（IVUS）视频图像中计算冠状动脉的管腔面积。首先，根据IVUS视频帧的连续性确定动脉内壁的搜索范围。接下来，计算内部和外部能量以描述动脉壁的平滑度和灰度...

A method for localization and segmentation of bifurcated aortic endografts in computed tomographic angiography (CTA) images is presented. The graft position is determined by detecting radiopaque markers sewn on the outside of the graft. The user indicates the first and the last marker, whereupon the remaining markers are automatically detected. This is achieved by first detecting marker-like struc...

提出了一种在计算机断层扫描血管造影（CTA）图像中对分叉型主动脉内支架进行定位与分割的方法。支架位置通过检测缝在支架外部的放射性标记来确定。用户指示第一个和最后一个标记，随后自动检测其余标记。这是通过首先检测类似标记的结构来实现...