Volume 21, Issue 11

A new approach is presented for elastic registration of medical images, and is applied to magnetic resonance images of the brain. Experimental results demonstrate very high accuracy in superposition of images from different subjects. There are two major novelties in the proposed algorithm. First, it uses an attribute vector, i.e., a set of geometric moment invariants (GMIs) that are defined on each voxel in an image and are calculated from the tissue maps, to reflect the underlying anatomy at different scales. The attribute vector, if rich enough, can distinguish between different parts of an image, which helps establish anatomical correspondences in the deformation procedure; it also helps reduce local minima, by reducing ambiguity in potential matches. This is a fundamental deviation of our method, referred to as the hierarchical attribute matching mechanism for elastic registration (HAMMER), from other volumetric deformation methods, which are typically based on maximizing image similarity. Second, in order to avoid being trapped by local minima, i.e., suboptimal poor matches, HAMMER uses a successive approximation of the energy function being optimized by lower dimensional smooth energy functions, which are constructed to have significantly fewer local minima. This is achieved by hierarchically selecting the driving features that have distinct attribute vectors, thus, drastically reducing ambiguity in finding correspondence. A number of experiments demonstrate that the proposed algorithm results in accurate superposition of image data from individuals with significant anatomical differences.

提出了一种用于医学图像弹性配准的新方法，并将其应用于脑部磁共振图像。实验结果表明，该方法在来自不同受试者的图像叠加中具有非常高的准确性。所提出的算法有两个主要创新点。首先，它使用属性向量，即一组定义在图像中每个体素上并从组织图中计算得到的几何矩不变量（GMIs），来反映不同尺度下的底层解剖结构。属性向量如果足够丰富，可以区分图像的不同部分，这有助于在变形过程中建立解剖对应关系；它还有助于通过减少潜在匹配中的模糊性来减少局部极小值。这是我们的方法（称为用于弹性配准的层次属性匹配机制，HAMMER）与其他通常基于最大化图像相似性的体积变形方法的根本区别。其次，为了避免陷入局部极小值（即次优的差匹配），HAMMER使用连续逼近被优化的能量函数，通过构造具有显著较少局部极小值的低维光滑能量函数来实现。这是通过层次性地选择具有独特属性向量的驱动特征来实现的，从而大幅减少寻找对应关系时的模糊性。多项实验表明，所提出的算法能够精确叠加具有显著解剖差异的个体的图像数据。

For liver surgical planning, the structure and morphology of the hepatic vessels and their relationship to tumors are of major interest. To achieve a fast and robust assistance with optimal quantitative and visual information, we present methods for a geometrical and structural analysis of vessel systems. Starting from the raw image data a sequence of image processing steps has to be carried out u...

对于肝脏手术规划，肝血管的结构和形态及其与肿瘤的关系是主要关注点。为了提供快速、稳健的辅助以及最佳的定量和视觉信息，我们提出了血管系统的几何和结构分析方法。从原始图像数据开始，需要执行一系列图像处理步骤...

A novel extension of active appearance models (AAMs) for automated border detection in echocardiographic image sequences is reported. The active appearance motion model (AAMM) technique allows fully automated robust and time-continuous delineation of left ventricular (LV) endocardial contours over the full heart cycle with good results. Nonlinear intensity normalization was developed and employed ...

本文报道了一种用于超声心动图像序列中自动边界检测的主动外观模型（AAM）的新扩展。主动外观运动模型（AAMM）技术能够在整个心动周期内实现左心室（LV）心内膜边界的全自动、鲁棒且时间连续的描绘，并取得了良好的效果。开发并采用了非线性强度归一化方法...

We show an iterative reconstruction framework for diffraction ultrasound tomography. The use of broad-band illumination allows significant reduction of the number of projections compared to straight ray tomography. The proposed algorithm makes use of forward nonuniform fast Fourier transform (NUFFT) for iterative Fourier inversion. Incorporation of total variation regularization allows the reducti...

我们展示了一种用于衍射超声层析成像的迭代重建框架。与直射线层析成像相比，使用宽带照明可以显著减少投影数量。所提出的算法利用前向非均匀快速傅里叶变换（NUFFT）进行迭代傅里叶反演。结合总变差正则化可以减少...

A Subvolume-based algorithm for elastic Ultrasound REgistration (SURE) was developed and evaluated. Designed primarily to improve spatial resolution in three-dimensional compound imaging, the algorithm registers individual image volumes nonlinearly before combination into compound volumes. SURE works in one or two stages, optionally using MIAMI Fuse/spl copy/ software first to determine a global a...

开发并评估了一种基于子块的弹性超声配准算法（SURE）。该算法主要旨在提高三维复合成像的空间分辨率，在组合成复合体积之前，对单个图像体积进行非线性配准。SURE可在一个或两个阶段中工作，可选地首先使用MIAMI Fuse软件确定全局...

Penalized iterative algorithms for image reconstruction in emission tomography contain conditions on which kind of images are accepted as solutions. The penalty term has commonly been a function of pairwise pixel differences in the activity in a local neighborhood, such that smooth images are favored. Attempts to ensure better edge and detail preservation involve difficult tailoring of parameter v...

发射断层扫描中用于图像重建的惩罚性迭代算法包含了对何种图像被接受为解的条件。惩罚项通常是局部邻域内活动像素对差异的函数，因此倾向于平滑图像。为确保更好的边缘和细节保留的尝试涉及到参数v的困难调整...

We present a new approach to anisotropic diffusion based on a multidirectional diffusion flux. The diffusion flux is decomposed in an orthogonal basis, effectively enabling enhancement of contours as well as diffusion along the contours. To this end, we have selected a three-dimensional basis that depicts the directions of principal curvature and has an interesting interpretation in the context of the vessels. The diffusion function associated to each vector of the basis depends on the first-order derivative of the intensity in this direction, instead of the traditional norm of the smoothed gradient. Accordingly, we present the results of a restoration of computed tomography data of the liver.

我们提出了一种基于多方向扩散通量的各向异性扩散新方法。扩散通量在正交基上分解，有效地实现了轮廓增强以及沿轮廓的扩散。为此，我们选择了一个三维基，该基描述了主曲率方向，并在……背景下具有有趣的解释。

Characterizing the response of the brain to a stimulus based on functional magnetic resonance imaging data is a major challenge due to the fact that the response time delay of the brain may be different from one stimulus phase to the next and from pixel to pixel. To enhance detectability, this work introduces the use of a curve evolution approach that provides separate estimates of the response ti...

基于功能性磁共振成像数据表征大脑对刺激的反应是一个重大挑战，因为大脑的反应时间延迟可能因刺激阶段和像素而异。为了提高可检测性，本文引入了一种曲线演化方法，该方法提供了反应时间的独立估计...

In this study, we examine longitudinal aliasing properties in multislice helical computed tomography (CT) volumes reconstructed under the multiple parallel fanbeam approximation by use of a 180LI-type algorithm. We focus on the differences between the multislice case and the single-slice case, which has been studied previously. Specifically, we examine longitudinal aliasing properties in four-slic...

在这项研究中，我们检查了在多重平行扇束近似下使用180LI型算法重建的多排螺旋计算机断层扫描（CT）体积中的纵向混叠特性。我们关注多排情况与之前研究过的单排情况之间的差异。具体而言，我们检查了四排...中的纵向混叠特性。

In this paper, we present a new mathematical method that synthesizes normal data sets for quantification of regional myocardium perfusion. In clinical practice, regional myocardial perfusion is often measured with a gamma camera and quantified via circumferential profile analysis. Normal reference profile data is used to increase the accuracy of the clinical interpretations. Our goal is to create ...

本文提出了一种新的数学方法，用于合成评估局部心肌灌注的正常数据集。在临床实践中，局部心肌灌注通常使用伽马相机测量，并通过周向轮廓分析进行量化。正常参考轮廓数据用于提高临床解释的准确性。我们的目标是创建...