Volume 27, Issue 12

The projection data measured in computed tomography (CT) and, consequently, the slices reconstructed from these data are noisy. We present a new wavelet based structure-preserving method for noise reduction in CT-images that can be used in combination with different reconstruction methods. The approach is based on the assumption that data can be decomposed into information and temporally uncorrelated noise. In CT two spatially identical images can be generated by reconstructions from disjoint subsets of projections: using the latest generation dual source CT-scanners one image can be reconstructed from the projections acquired at the first, the other image from the projections acquired at the second detector. For standard CT-scanners the two images can be generated by splitting up the set of projections into even and odd numbered projections. The resulting images show the same information but differ with respect to image noise. The analysis of correlations between the wavelet representations of the input images allows separating information from noise down to a certain signal-to-noise level. Wavelet coefficients with small correlation are suppressed, while those with high correlations are assumed to represent structures and are preserved. The final noise-suppressed image is reconstructed from the averaged and weighted wavelet coefficients of the input images. The proposed method is robust, of low complexity and adapts itself to the noise in the images. The quantitative and qualitative evaluation based on phantom as well as real clinical data showed, that high noise reduction rates of around 40% can be achieved without noticeable loss of image resolution.

计算机断层扫描（CT）的投影数据以及从这些数据重建的切片都存在噪声。我们提出了一种新的基于小波的结构保持方法，用于CT图像的降噪，该方法可与不同的重建方法结合使用。该方法基于数据可以分解为信息和时间不相关噪声的假设。在CT中，可以通过从不相交的投影子集重建生成两个空间相同的图像：使用最新一代双源CT扫描仪，可以从第一探测器获取的投影重建一幅图像，从第二探测器获取的投影重建另一幅图像。对于标准CT扫描仪，可以通过将投影集分为奇数和偶数编号的投影来生成两幅图像。生成的图像显示相同的信息，但图像噪声不同。分析输入图像的小波表示之间的相关性，可以在一定信噪比水平下将信息与噪声分离。相关性小的小波系数被抑制，而相关性高的系数假定代表结构并被保留。最终降噪图像由输入图像的平均和加权小波系数重建。该方法鲁棒性强、复杂度低，并能自适应图像中的噪声。基于体模和真实临床数据的定性和定量评估表明，可以实现约40%的高降噪率，且无明显图像分辨率损失。

This paper describes the use of color image analysis to automatically discriminate between oesophagus, stomach, small intestine, and colon tissue in wireless capsule endoscopy (WCE). WCE uses “pill-cam” technology to recover color video imagery from the entire gastrointestinal tract. Accurately reviewing and reporting this data is a vital part of the examination, but it is tedious and time consuming. Automatic image analysis tools play an important role in supporting the clinician and speeding up this process. Our approach first divides the WCE image into subimages and rejects all subimages in which tissue is not clearly visible. We then create a feature vector combining color, texture, and motion information of the entire image and valid subimages. Color features are derived from hue saturation histograms, compressed using a hybrid transform, incorporating the discrete cosine transform and principal component analysis. A second feature combining color and texture information is derived using local binary patterns. The video is segmented into meaningful parts using support vector or multivariate Gaussian classifiers built within the framework of a hidden Markov model. We present experimental results that demonstrate the effectiveness of this method.

本文描述了使用彩色图像分析在无线胶囊内窥镜（WCE）中自动区分食道、胃、小肠和结肠组织的方法。WCE使用“药丸相机”技术从整个胃肠道获取彩色视频图像。准确审查和报告这些数据是检查的重要部分，但繁琐且耗时。

Though laser speckle contrast imaging enables the measurement of scattering particle dynamics with high temporal resolution, the subsequent processing has previously been much slower. In prior studies, generating a laser speckle contrast image required about 1 s to process a raw image potentially collected in 10 ms or less. In this paper, novel algorithms are described which are demonstrated to co...

尽管激光散斑对比成像能够以高时间分辨率测量散射粒子动力学，但后续处理以前要慢得多。在先前的研究中，生成一张激光散斑对比图像需要大约1秒来处理可能在10毫秒或更短时间内采集的原始图像。本文描述了一些新算法，这些算法被证明能够...

Quantitative reconstruction of cone beam X-ray computed tomography (CT) datasets requires accurate modeling of scatter, beam-hardening, beam profile, and detector response. Typically, commercial imaging systems use fast empirical corrections that are designed to reduce visible artifacts due to incomplete modeling of the image formation process. In contrast, Monte Carlo (MC) methods are much more a...

锥形束X射线计算机断层扫描（CT）数据集的定量重建需要对散射、束硬化、束轮廓和探测器响应进行精确建模。通常，商用成像系统使用快速经验校正，旨在减少由于图像形成过程建模不完整而产生的可见伪影。相比之下，蒙特卡洛（MC）方法则更为…

One of the most important technical challenges in image-guided intervention is to obtain a precise transformation between the intrainterventional patient's anatomy and corresponding preinterventional 3-D image on which the intervention was planned. This goal can be achieved by acquiring intrainterventional 2-D images and matching them to the preinterventional 3-D image via 3-D/2-D image registrati...

图像引导介入中最关键的技术挑战之一是如何在介入过程中获取患者解剖结构与术前三维图像之间的精确变换，以便进行计划中的介入操作。这一目标可以通过获取术中的二维图像，并通过三维/二维图像配准将其与术前三维图像匹配来实现。

We present a new method for three-dimensional (3-D) visualization and identification of biological microorganisms using partially temporal incoherent light in-line (PTILI) computational holographic imaging and multivariate statistical methods. For 3-D data acquisition of biological microorganisms, the band-pass filtered white light is used to illuminate a biological sample. The transversely and lo...

我们提出了一种使用部分时间非相干光同轴（PTILI）计算全息成像和多元统计方法进行生物微生物三维（3-D）可视化和识别的新方法。对于生物微生物的三维数据采集，使用带通滤波的白光照射生物样本。横向和纵向分辨率以及成像深度通过数值重建算法优化。该方法无需扫描即可提供微生物的3-D图像，适用于动态观测。

Spatial normalization is frequently used to map data to a standard coordinate system by removing intersubject morphological differences, thereby allowing for group analysis to be carried out. The work presented in this paper is motivated by the need for an automated cortical surface normalization technique that will automatically identify homologous cortical landmarks and map them to the same coor...

空间归一化常用于通过消除个体间的形态差异将数据映射到标准坐标系，从而进行组分析。本文提出的工作源于对自动化皮层表面归一化技术的需求，该技术能够自动识别同源皮层标志点并将其映射到相同的坐标...

It has been known for some time that many tumors have a significantly different conductivity and permittivity from surrounding normal tissue. This high “contrast” in tissue electrical properties, occurring between a few kilohertz and several megahertz, may permit differentiating malignant from benign tissues. Here we show the ability of electrical impedance spectroscopy (EIS) to roughly localize a...

众所周知，许多肿瘤的电导率和介电常数与周围正常组织有显著差异。这种组织电学特性的高对比度，发生在几千赫兹到几兆赫兹之间，可能有助于区分恶性和良性组织。在这里，我们展示了电阻抗谱（EIS）大致定位...

Magnetic resonance imaging (MRI) is a safe and reliable medical imaging method providing good soft tissue contrast while avoiding harmful ionizing radiation. It is highly desirable to use the MRI technology for interventional procedures. However, due to resonance effects that can result in tissue heating, long conducting cables must be avoided. Motivated by the need for more radio-frequency (RF) s...

磁共振成像（MRI）是一种安全可靠的医学成像方法，能提供良好的软组织对比度，同时避免有害的电离辐射。将MRI技术用于介入手术是非常理想的。然而，由于共振效应可能导致组织加热，必须避免长导线。为了满足对更多射频（RF）...

Magnetic resonance electrical impedance tomography (MREIT) attempts to provide conductivity images of an electrically conducting object with a high spatial resolution. When we inject current into the object, it produces internal distributions of current density J and magnetic flux density B=(Bx,By,Bz). By using a magnetic resonance imaging (MRI) scanner, we can measure Bz data where z is the direc...

磁共振电阻抗成像（MREIT）旨在提供具有高空间分辨率的导电物体的电导率图像。当我们向物体注入电流时，会产生电流密度J和磁通密度B=(Bx,By,Bz)的内部分布。通过使用磁共振成像（MRI）扫描仪，我们可以测量Bz数据，其中z是方向...

Information on uterine blood flow rate during pregnancy would widely improve our knowledge on feto-placental patho-physiology. Ultrasonographic flow rate evaluation requires the knowledge of the spatial velocity profiles throughout the investigated vessel; these data may be obtained from hemodynamic simulations with accurate computational models. Recently, computational models of superficial vesse...

妊娠期子宫血流速率的信息将广泛提高我们对胎儿-胎盘病理生理学的认识。超声血流速率评估需要了解所研究血管内的空间速度分布；这些数据可以通过精确的计算模型进行血流动力学模拟获得。近期，浅表血管的计算模型...

Provides a listing of current committee members and society officers.

提供当前委员会成员和协会官员的列表。

This page or pages intentionally left blank.

本页或若干页有意留白。

Prospective authors are requested to submit new, unpublished manuscripts for inclusion in the upcoming event described in this call for papers.

诚邀潜在作者提交新的、未发表的手稿，以纳入本次征稿通知中描述的即将举行的活动。

Provides instructions and guidelines to prospective authors who wish to submit manuscripts.

为希望提交稿件的新作者提供说明和指南。

Presents the table of contents for this issue of the periodical.

介绍本期期刊的目录。

This index covers all technical items - papers, correspondence, reviews, etc. - that appeared in this periodical during the year, and items from previous years that were commented upon or corrected in this year. Departments and other items may also be covered if they have been judged to have archival value. The Author Index contains the primary entry for each item, listed under the first author's ...

本索引涵盖了本年度该期刊中出现的所有技术项目——论文、通信、评论等，以及前几年在本年度中被评论或更正的条目。其他项目（如部门）如果被认为具有档案价值，也可能被收录。作者索引包含每个项目的主要条目，列在第一作者名下……