Volume 26, Issue 6

Remarkable progress in positron emission tomography (PET) development has occurred in recent years, in hardware, software, and computer implementation of image reconstruction. Recent development in PET scanners such as the high-resolution research tomograph (HRRT) developed by CTI (now Siemens) represents such a case and is capable of greatly enhanced resolution as well as sensitivity. In these PET scanners, the amount of coincidence line data collected contains more than $4.5\times 10^{9}$ coincidence lines of response generated by as many nuclear detectors as 120 000. This formidable amount of data and the reconstruction of this data set pose a real problem in HRRT and have also been of the major bottle neck in further developments of high resolution PET scanners as well as their applications. In these classes of PET scanners, therefore, obtaining one set of reconstructed images often requires many hours of image reconstruction. For example, in HRRT with full data collection in a normal brain scan (using SPAN 3), the image reconstruction time is close to 80 min, making it practically impossible to attempt any list-mode-based dynamic imaging since the image reconstruction time would take many days (as much as 43 h or more for 32–frame dynamic image reconstruction). To remedy this data-handling problem in image reconstruction, we developed a new algorithm based on the symmetry properties of the projection and backprojection processes, especially in the 3-D OSEM algorithm where multiples of projection and back-projection are required. In addition, the single-instruction multiple-data (SIMD) technique also allowed us to successfully incorporate the symmetry properties mentioned above, thereby effectively reducing the total image reconstruction time to a few minutes. We refer to this technique as the symmetry and SIMD-based projection-backprojection (SSP) technique or algorithm and the details of th

近年来，正电子发射断层扫描（PET）在硬件、软件和图像重建的计算机实现方面取得了显著进展。最近PET扫描仪的发展，例如CTI（现为西门子）开发的高分辨率研究断层扫描仪（HRRT）就是一个例子，它能够大大提高分辨率和灵敏度。在这些PET扫描仪中，收集到的符合线数据量包含超过4.5×10^9条符合响应线，由多达120,000个核探测器生成。这一庞大的数据量及其重建在HRRT中构成了一个实际问题，并且也是高分辨率PET扫描仪进一步发展及其应用的主要瓶颈之一。因此，在这类PET扫描仪中，获取一组重建图像通常需要数小时的图像重建时间。例如，在正常脑部扫描（使用SPAN 3）中，HRRT完全数据采集的图像重建时间接近80分钟，这使得任何基于列表模式的动态成像几乎不可能，因为图像重建时间需要数天（32帧动态图像重建需要43小时或更长时间）。为了解决图像重建中的这一数据处理问题，我们开发了一种基于投影和反投影过程对称性的新算法，特别是在需要多次投影和反投影的三维OSEM算法中。此外，单指令多数据（SIMD）技术也使我们能够成功结合上述对称性，从而有效将总图像重建时间减少到几分钟。我们将此技术称为基于对称性和SIMD的投影-反投影（SSP）技术或算法。

A comparison between two nonlinear diffusion methods for denoising OCT images is performed. Specifically, we compare and contrast the performance of the traditional nonlinear Perona-Malik filter with a complex diffusion filter that has been recently introduced by Gilboa . The complex diffusion approach based on the generalization of the nonlinear scale space to the complex domain by combining the ...

对两种用于OCT图像去噪的非线性扩散方法进行了比较。具体来说，我们比较和对比了传统的非线性Perona-Malik滤波器与Gilboa等人最近引入的复扩散滤波器的性能。复扩散方法基于将非线性尺度空间推广到复数域，通过结合...

Maps of local tissue compression or expansion are often computed by comparing magnetic resonance imaging (MRI) scans using nonlinear image registration. The resulting changes are commonly analyzed using tensor-based morphometry to make inferences about anatomical differences, often based on the Jacobian map, which estimates local tissue gain or loss. Here, we provide rigorous mathematical analyses...

局部组织压缩或扩张的映射通常通过比较磁共振成像（MRI）扫描并使用非线性图像配准来计算。由此产生的变化通常使用基于张量的形态测量进行分析，以推断解剖差异，通常基于雅可比映射，该映射估计局部组织的增加或损失。在这里，我们提供了严格的数学分析...

We propose a technique for the automated detection of malignant masses in screening mammography. The technique is based on the presence of concentric layers surrounding a focal area with suspicious morphological characteristics and low relative incidence in the breast region. Mammographic locations with high concentration of concentric layers with progressively lower average intensity are consider...

我们提出了一种用于筛查性乳腺X线摄影中恶性肿块自动检测的技术。该技术基于围绕可疑形态特征且乳腺区域发病率较低的局灶区域的同心层存在。具有高浓度平均强度逐渐降低的同心层的乳腺X线摄影位置被认为是可疑的。

In medical imaging, parameterized 3-D surface models are useful for anatomical modeling and visualization, statistical comparisons of anatomy, and surface-based registration and signal processing. Here we introduce a parameterization method based on Riemann surface structure, which uses a special curvilinear net structure (conformal net) to partition the surface into a set of patches that can each...

在医学影像中，参数化的三维表面模型对于解剖建模和可视化、解剖结构的统计比较以及基于表面的配准和信号处理非常有用。这里我们介绍一种基于黎曼曲面结构的参数化方法，该方法使用特殊的曲线网格结构（共形网格）将表面划分为多个面片，每个面片可以...

Referenceless proton resonance frequency (PRF) shift thermometry provides a means to measure temperature changes during minimally invasive thermotherapy that is inherently robust to motion and tissue displacement. However, if the referenceless method is used to determine temperature changes during prostate ablation, phase gaps between water and fat in image regions used to determine the background...

无参考质子共振频率（PRF）位移测温提供了一种在微创热疗过程中测量温度变化的方法，该方法本质上对运动和组织位移具有鲁棒性。然而，如果使用无参考方法确定前列腺消融过程中的温度变化，用于确定背景的图像区域中水和脂肪之间的相位间隙...

Laser speckle imaging has increasingly become a viable technique for real-time medical imaging. However, the computational intricacies and the viewing experience involved limit its usefulness for real-time monitors such as those intended for neurosurgical applications. In this paper, we propose a new technique, tLASCA, which processes statistics primarily in the temporal direction using the laser ...

激光散斑成像已逐渐成为一种可行的实时医学成像技术。然而，其计算复杂性和观看体验限制了其在神经外科等实时监测中的实用性。本文提出了一种新技术tLASCA，该技术主要利用激光在时间方向上进行统计处理...

In this paper, a method for maximizing the probability of prostate cancer detection via biopsy is presented, by combining image analysis and optimization techniques. This method consists of three major steps. First, a statistical atlas of the spatial distribution of prostate cancer is constructed from histological images obtained from radical prostatectomy specimen. Second, a probabilistic optimiz...

本文提出了一种结合图像分析和优化技术的方法，以最大化通过活检检测前列腺癌的概率。该方法包括三个主要步骤。首先，从根治性前列腺切除术标本获得的组织学图像构建前列腺癌空间分布的统计图谱。其次，进行概率优化...

This paper presents methods and a clinical procedure for integrating B-mode ultrasound images tagged with position information with a planning computed tomography (CT) scan for radiotherapy. A workflow is described that allows the integration of these modalities into the clinic. A surface mapping approach provides a preregistration of the ultrasound image borders onto the patient's skin. Successiv...

本文介绍了将带有位置信息的B型超声图像与用于放疗的计划计算机断层扫描（CT）相结合的方法和临床流程。描述了一种将这些模式整合到临床中的工作流程。表面映射方法提供了超声图像边界在患者皮肤上的预配准。

This paper addresses the problem of statistical analysis of diffusion tensor magnetic resonance images (DT-MRI). DT-MRI cannot be analyzed by commonly used linear methods, due to the inherent nonlinearity of tensors, which are restricted to lie on a nonlinear submanifold of the space in which they are defined, namely R6. We estimate this submanifold using the isomap manifold learning technique and...

本文探讨了扩散张量磁共振图像（DT-MRI）的统计分析问题。由于张量固有的非线性特性，它们被限制在定义空间（即R6）的一个非线性子流形上，因此DT-MRI无法使用常用的线性方法进行分析。我们利用Isomap流形学习技术来估计这个子流形，并...

The combined assessment of data obtained by positron emission tomography (PET) and gene array techniques provide new capabilities for the interpretation of kinetic tracer studies. The correlative analysis of the data helps to detect dependencies of the kinetics of radiotracer on gene expression. Furthermore, gene expression may be predicted using regression functions if a significant correlation e...

通过正电子发射断层扫描（PET）和基因阵列技术获得的数据的联合评估，为解释动力学示踪研究提供了新的能力。数据的相关分析有助于检测放射性示踪剂动力学对基因表达的依赖性。此外，如果存在显著相关性，可以使用回归函数预测基因表达...

A new method for imaging the vibration mode of an object is investigated. The radiation force of ultrasound is used to scan the object at a resonant frequency of the object. The vibration of the object is measured by laser and the resulting acoustic emission from the object is measured by a hydrophone. It is shown that the measured signal is proportional to the value of the mode shape at the focal...

研究了一种新的物体振动模式成像方法。利用超声辐射力在物体的共振频率下对物体进行扫描。通过激光测量物体的振动，并通过水听器测量物体产生的声发射。结果表明，测量信号与焦点处的模态振型值成正比...

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