Volume 27, Issue 8

The problem of motion is well known in positron emission tomography (PET) studies. The PET images are formed over an elongated period of time. As the patients cannot hold breath during the PET acquisition, spatial blurring and motion artifacts are the natural result. These may lead to wrong quantification of the radioactive uptake. We present a solution to this problem by respiratory-gating the PET data and correcting the PET images for motion with optical flow algorithms. The algorithm is based on the combined local and global optical flow algorithm with modifications to allow for discontinuity preservation across organ boundaries and for application to 3-D volume sets. The superiority of the algorithm over previous work is demonstrated on software phantom and real patient data.

在正电子发射断层扫描（PET）研究中，运动问题众所周知。PET图像是在较长时间内形成的。由于患者在PET采集期间无法屏住呼吸，空间模糊和运动伪影是自然结果。这可能导致对放射性摄取的错误量化。我们通过呼吸门控PET数据并使用光流算法校正PET图像来解决这一问题。该算法基于局部和全局相结合的光流算法，并进行了修改，以允许跨器官边界的间断保持并应用于三维体数据集。通过在软件体模和真实患者数据上的实验，证明了该算法相对于先前研究的优越性。

With continuing improvements in spatial resolution of positron emission tomography (PET) scanners, small patient movements during PET imaging become a significant source of resolution degradation. This work develops and investigates a comprehensive formalism for accurate motion-compensated reconstruction which at the same time is very feasible in the context of high-resolution PET. In particular, ...

随着正电子发射断层扫描（PET）扫描仪空间分辨率的持续提高，PET成像过程中患者的微小移动成为分辨率退化的一个重要来源。本研究开发并研究了一种用于精确运动补偿重建的综合形式化方法，同时该方法在高分辨率PET中也非常可行。特别地，……

Coherent X-ray scattering is related to the electron density distribution by a Fourier transform, and therefore a window into the microscopic structures of biological samples. Current techniques of scattering rely on small-angle measurements from highly collimated X-ray beams produced from synchrotron light sources. Imaging of the distribution of scattering provides a new contrast mechanism which is different from absorption radiography, but is a lengthy process of raster or line scans of the beam over the object. Here, we describe an imaging technique in the spatial frequency domain capable of acquiring both the scattering and absorption distributions in a single exposure. We present first results obtained with conventional X-ray equipment. This method interposes a grid between the X-ray source and the imaged object, so that the grid-modulated image contains a primary image and a grid harmonic image. The ratio between the harmonic and primary images is shown to be a pure scattering image. It is the auto-correlation of the electron density distribution at a specific distance. We tested a number of samples at 60–200 nm autocorrelation distance, and found the scattering images to be distinct from the absorption images and reveal new features. This technique is simple to implement, and should help broaden the imaging applications of X-ray scattering.

相干X射线散射通过傅里叶变换与电子密度分布相关，因此是生物样品微观结构的一个窗口。当前的散射技术依赖于同步辐射光源产生的高度准直X射线束的小角测量。散射分布的成像提供了一种新的对比机制……

We describe the application of a time domain diffuse fluorescence tomography system for whole body small animal imaging. The key features of the system are the use of point excitation in free space using ultrashort laser pulses and noncontact detection using a gated, intensified charge-coupled device (CCD) camera. Mouse shaped epoxy phantoms, with embedded fluorescent inclusions, were used to veri...

我们描述了一种时间域扩散荧光断层成像系统用于全身小动物成像的应用。该系统的主要特点是使用超短激光脉冲在自由空间进行点激发，并使用门控增强型电荷耦合器件（CCD）相机进行非接触检测。使用嵌入荧光夹杂物的鼠形环氧树脂体模来验证系统的性能。

We present a new tensor-based morphometric framework that quantifies cortical shape variations using a local area element. The local area element is computed from the Riemannian metric tensors, which are obtained from the smooth functional parametrization of a cortical mesh. For the smooth parametrization, we have developed a novel weighted spherical harmonic (SPHARM) representation, which general...

我们提出了一种新的基于张量的形态测量框架，通过局部面积元素量化皮层形状变化。局部面积元素由黎曼度量张量计算得到，这些张量来源于皮层网格的平滑函数参数化。为了平滑参数化，我们开发了一种新颖的加权球谐（SPHARM）表示，该表示推广...

Two-dimensional or 3-D visual guidance is often used for minimally invasive cardiac surgery and diagnosis. This visual guidance suffers from several drawbacks such as limited field of view, loss of signal from time to time, and in some cases, difficulty of interpretation. These limitations become more evident in beating-heart procedures when the surgeon has to perform a surgical procedure in the p...

二维或三维视觉引导常用于微创心脏手术和诊断。这种视觉引导存在若干缺点，如视野受限、信号偶尔丢失，以及在某些情况下难以解释。当外科医生需要在跳动的心脏上进行手术时，这些局限性变得更加明显。

A deformable registration method is proposed for registering a normal brain atlas with images of brain tumor patients. The registration is facilitated by first simulating the tumor mass effect in the normal atlas in order to create an atlas image that is as similar as possible to the patient's image. An optimization framework is used to optimize the location of tumor seed as well as other paramete...

提出了一种将正常脑图谱与脑肿瘤患者图像进行可变形配准的方法。该配准通过首先在正常图谱中模拟肿瘤占位效应来促进，从而创建尽可能与患者图像相似的图谱图像。使用优化框架来优化肿瘤种子位置以及其他参数...

The purposes of this study were to develop a semiautomated cardiac contour segmentation method for use with cine displacement-encoded MRI and evaluate its accuracy against manual segmentation. This segmentation model was designed with two distinct phases: preparation and evolution. During the model preparation phase, after manual image cropping and then image intensity standardization, the myocard...

本研究的目的是开发一种用于电影位移编码MRI的半自动心脏轮廓分割方法，并评估其与手动分割的准确性。该分割模型设计有两个不同的阶段：准备和演化。在模型准备阶段，经过手动图像裁剪和图像强度标准化后，心肌...

The existing differential approaches for localization of 3-D anatomic point landmarks in 3-D images are sensitive to noise and usually extract numerous spurious landmarks. The parametric model-based approaches are not practically usable for localization of landmarks that can not be modeled by simple parametric forms. Some dedicated methods using anatomic knowledge to identify particular landmarks ...

现有的用于三维图像中三维解剖点地标定位的微分方法对噪声敏感，且通常提取大量虚假地标。基于参数模型的方法在实际中无法用于定位那些不能用简单参数形式建模的地标。一些利用解剖知识识别特定地标的专用方法...

Multicolor fluorescence in situ hybridization (M-FISH) techniques provide color karyotyping that allows simultaneous analysis of numerical and structural abnormalities of whole human chromosomes. Chromosomes are stained combinatorially in M-FISH. By analyzing the intensity combinations of each pixel, all chromosome pixels in an image are classified. Often, the intensity distributions between diffe...

多色荧光原位杂交（M-FISH）技术提供彩色核型分析，允许同时分析整个人类染色体的数量和结构异常。染色体在M-FISH中被组合染色。通过分析每个像素的强度组合，图像中的所有染色体像素被分类。通常，不同染色体之间的强度分布存在差异...

Computed tomography (CT) has a trend towards higher resolution and higher noise. This development has increased the interest in anisotropic smoothing techniques for CT, which aim to reduce noise while preserving structures of interest. However, existing smoothing techniques are slow, which makes clinical application difficult. Furthermore, the published methods have limitations with respect to pre...

计算机断层扫描（CT）有向更高分辨率和更高噪声发展的趋势。这一发展增加了对CT各向异性平滑技术的兴趣，该技术旨在降低噪声的同时保留感兴趣的结构。然而，现有的平滑技术速度较慢，使得临床应用困难。此外，已发表的方法在预处理方面存在局限性。

This paper deals with the problem of tracking cardiac motion and deformation using velocity-encoded magnetic resonance imaging. We expand upon an earlier described method and fit a spatiotemporal motion model to measured velocity data. We investigate several different spatial elements both qualitatively and quantitatively using phantom measurements and data from human subjects. In addition, we als...

本文涉及使用速度编码磁共振成像追踪心脏运动和变形的问题。我们扩展了先前描述的方法，并将时空运动模型拟合到测量的速度数据。我们使用体模测量和人类受试者的数据，定性和定量地研究了几个不同的空间元素。此外，我们还...

Contrast-enhanced magnetic resonance imaging (MRI) is useful to study the infiltration of cells in vivo. This research adopts ultrasmall superparamagnetic iron oxide (USPIO) particles as contrast agents. USPIO particles administered intravenously can be endocytosed by circulating immune cells, in particular, macrophages. Hence, macrophages are labeled with USPIO particles. When a transplanted hear...

对比增强磁共振成像（MRI）有助于研究体内细胞的浸润。本研究采用超小型超顺磁性氧化铁（USPIO）颗粒作为对比剂。静脉注射的USPIO颗粒可被循环免疫细胞（尤其是巨噬细胞）内吞。因此，巨噬细胞被USPIO颗粒标记。当移植的心脏...

We investigate the possibility to develop methodologies for assessing effect specific structural changes of the breast tissue using a general statistical machine learning framework. We present an approach of obtaining objective mammographic pattern measures quantifying a specific biological effect, such as hormone replacement therapy (HRT). We compare results using this approach to using standard ...

我们研究使用通用统计机器学习框架开发评估乳腺组织效应特异性结构变化方法学的可能性。我们提出了一种获取客观乳腺摄影模式测量的方法，该测量量化特定生物效应，如激素替代疗法（HRT）。我们比较了使用该方法与使用标准...的结果。

One of the greatest challenges facing iterative fully-3-D positron emission tomography (PET) reconstruction is the issue of long reconstruction times due to the large number of measurements for 3-D mode as compared to 2-D mode. A rotate-and-slant projector has been developed that takes advantage of symmetries in the geometry to compute volumetric projections to multiple oblique sinograms in a comp...

迭代全3D正电子发射断层扫描（PET）重建面临的最大挑战之一是由于3D模式与2D模式相比测量数量巨大导致的重建时间长。已经开发了一种旋转倾斜投影器，它利用几何对称性计算体积投影到多个倾斜正弦图，从而在...

This paper introduces and evaluates a block-iterative fisher scoring (BFS) algorithm. The algorithm provides regularized estimation in tomographic models of projection data with Poisson variability. Regularization is achieved by penalized likelihood with a general quadratic penalty. Local convergence of the block-iterative algorithm is proven under conditions that do not require iteration dependen...

本文介绍并评估了一种块迭代费舍尔评分（BFS）算法。该算法为具有泊松变异性的投影数据断层模型提供正则化估计。正则化通过具有一般二次惩罚的惩罚似然实现。在不需要迭代依赖的条件下证明了块迭代算法的局部收敛性。

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