Volume 29, Issue 2

We aim at improving quantitative measures of emphysema in computed tomography (CT) images of the lungs. Current standard measures, such as the relative area of emphysema (RA), rely on a single intensity threshold on individual pixels, thus ignoring any interrelations between pixels. Texture analysis allows for a much richer representation that also takes the local structure around pixels into account. This paper presents a texture classification-based system for emphysema quantification in CT images. Measures of emphysema severity are obtained by fusing pixel posterior probabilities output by a classifier. Local binary patterns (LBP) are used as texture features, and joint LBP and intensity histograms are used for characterizing regions of interest (ROIs). Classification is then performed using a k nearest neighbor classifier with a histogram dissimilarity measure as distance. A 95.2% classification accuracy was achieved on a set of 168 manually annotated ROIs, comprising the three classes: normal tissue, centrilobular emphysema, and paraseptal emphysema. The measured emphysema severity was in good agreement with a pulmonary function test (PFT) achieving correlation coefficients of up to | r | = 0.79 in 39 subjects. The results were compared to RA and to a Gaussian filter bank, and the texture-based measures correlated significantly better with PFT than did RA.

我们旨在改进肺部计算机断层扫描（CT）图像中肺气肿的定量测量。当前的标准测量方法，如肺气肿相对面积（RA），依赖于单个像素的单一强度阈值，因此忽略了像素之间的任何相互关系。纹理分析允许更丰富的表示，同时也考虑像素周围的局部结构。本文提出了一种基于纹理分类的CT图像肺气肿定量系统。通过融合分类器输出的像素后验概率，获得肺气肿严重程度的度量。使用局部二值模式（LBP）作为纹理特征，并联合LBP和强度直方图来表征感兴趣区域（ROI）。然后使用k最近邻分类器进行分类，采用直方图相异性度量作为距离。在168个手动标注的ROI上实现了95.2%的分类准确率，包括三类：正常组织、小叶中心型肺气肿和间隔旁型肺气肿。测量的肺气肿严重程度与肺功能测试（PFT）具有良好的一致性，在39名受试者中相关系数高达|r|=0.79。将结果与RA和高斯滤波器组进行比较，基于纹理的测量与PFT的相关性显著优于RA。

We present a nonparametric regression method for denoising 3-D image sequences acquired via fluorescence microscopy. The proposed method exploits the redundancy of the 3-D+time information to improve the signal-to-noise ratio of images corrupted by Poisson-Gaussian noise. A variance stabilization transform is first applied to the image-data to remove the dependence between the mean and variance of...

我们提出了一种用于荧光显微镜采集的3D图像序列去噪的非参数回归方法。该方法利用3D+时间信息的冗余性来提高受泊松-高斯噪声污染图像的信噪比。首先对图像数据应用方差稳定变换以消除均值与方差之间的依赖关系...

Quantitative analysis of biological image data generally involves the detection of many subresolution spots. Especially in live cell imaging, for which fluorescence microscopy is often used, the signal-to-noise ratio (SNR) can be extremely low, making automated spot detection a very challenging task. In the past, many methods have been proposed to perform this task, but a thorough quantitative eva...

生物图像数据的定量分析通常涉及许多亚分辨率斑点的检测。特别是在活细胞成像中，常使用荧光显微镜，信噪比可能极低，使得自动斑点检测成为一项非常具有挑战性的任务。过去，已经提出了许多方法来完成这项任务，但迄今为止尚缺乏全面的定量评估。

In this paper, we propose the use of multiscale amplitude-modulation-frequency-modulation (AM-FM) methods for discriminating between normal and pathological retinal images. The method presented in this paper is tested using standard images from the early treatment diabetic retinopathy study. We use 120 regions of 40$\,\times\,$40 pixels containing four types of lesions commonly associated with dia...

本文提出使用多尺度调幅-调频（AM-FM）方法区分正常和病理视网膜图像。所提出的方法采用早期治疗糖尿病视网膜病变研究中的标准图像进行测试。我们使用了120个40×40像素的区域，包含四种常见于糖尿病视网膜病变的病灶类型。

Classification of brain images obtained through functional magnetic resonance imaging (fMRI) poses a serious challenge to pattern recognition and machine learning due to the extremely large feature-to-instance ratio. This calls for revision and adaptation of the current state-of-the-art classification methods. We investigate the suitability of the random subspace (RS) ensemble method for fMRI clas...

通过功能磁共振成像（fMRI）获取的脑图像分类对模式识别和机器学习提出了严峻挑战，因为特征与实例的比例极大。这需要修订和适应当前最先进的分类方法。我们研究了随机子空间（RS）集成方法在fMRI分类中的适用性...

Magnetic susceptibility is an important physical property of tissues, and can be used as a contrast mechanism in magnetic resonance imaging (MRI). Recently, targeting contrast agents by conjugation with signaling molecules and labeling stem cells with contrast agents have become feasible. These contrast agents are strongly paramagnetic, and the ability to quantify magnetic susceptibility could all...

磁化率是组织的重要物理性质，可用作磁共振成像（MRI）的对比机制。最近，通过信号分子结合靶向对比剂以及用对比剂标记干细胞已成为可行。这些对比剂是强顺磁性的，量化磁化率的能力可能...

A hybrid imaging system for simultaneous fluorescence tomography and X-ray computed tomography (XCT) of small animals has been developed and presented. The system capitalizes on the imaging power of a 360 °-projection free-space fluorescence tomography system, implemented within a microcomputed tomography scanner. Image acquisition is based on techniques that automatically adjust a series of imagi...

已经开发并展示了一种用于小动物同步荧光断层扫描和X射线计算机断层扫描（XCT）的混合成像系统。该系统利用了一个在微型计算机断层扫描仪内实现的360°投影自由空间荧光断层扫描系统的成像能力。图像采集基于自动调整一系列成像...

In this study, a combination of active shape model (ASM) and active appearance model (AAM) was used to segment the left and right ventricles of normal and Tetralogy of Fallot (TOF) hearts on 4-D (3-D+time) MR images. For each ventricle, a 4-D model was first used to achieve robust preliminary segmentation on all cardiac phases simultaneously and a 3-D model was then applied to each phase to improv...

本研究采用主动形状模型（ASM）和主动表观模型（AAM）相结合的方法，对正常和法洛四联症（TOF）心脏的左右心室在四维（三维+时间）磁共振图像上进行分割。对于每个心室，首先使用四维模型在所有心脏相同时进行稳健的初步分割，然后对每个相位应用三维模型以改进...

A pressure ulcer is a clinical pathology of localized damage to the skin and underlying tissue caused by pressure, shear, or friction. Diagnosis, treatment, and care of pressure ulcers are costly for health services. Accurate wound evaluation is a critical task for optimizing the efficacy of treatment and care. Clinicians usually evaluate each pressure ulcer by visual inspection of the damaged tis...

压力性溃疡是一种由压力、剪切力或摩擦力引起的皮肤及深层组织局部损伤的临床病理。压力性溃疡的诊断、治疗和护理对医疗服务来说成本高昂。准确的伤口评估是优化治疗和护理效果的关键任务。临床医生通常通过视觉检查受损组织来评估每个压力性溃疡...

The electric properties (EPs) of biological tissue, i.e., the electric conductivity and permittivity, can provide important information in the diagnosis of various diseases. The EPs also play an important role in specific absorption rate calculation, a major concern in high-field MRI, as well as in nonmedical areas such as wireless telecommunications. The high-field MRI system is accompanied by si...

生物组织的电特性，即电导率和介电常数，可以为各种疾病的诊断提供重要信息。在高场MRI中，电特性在特定吸收率计算中起着重要作用，这也是一个主要关注点，同时在无线电信等非医疗领域也具有重要意义。高场MRI系统伴随着...

Several different reconstruction algorithms have been proposed for photoacoustic tomography, most of which presuppose that the acoustic properties of the medium are constant and homogeneous. In practice, there are often unknown spatial variations in the acoustic properties, and these algorithms give, at best, only approximate estimates of the true image. The question as to which approach is the mo...

针对光声断层成像，已有多种重建算法被提出，其中大多数假设介质的声学特性恒定且均匀。然而在实际中，声学特性往往存在未知的空间变化，这些算法最多只能给出真实图像的近似估计。问题在于哪种方法最...

Ultrasound B-mode scanning based on the echo intensity has become an important clinical tool for routine breast screening. The efficacy of the Nakagami parametric image based on the distribution of the backscattered signals for quantifying properties of breast tissue was recently evaluated. The B-mode and Nakagami images reflect different physical characteristic of breast tumors: the former descri...

基于回声强度的超声B模式扫描已成为常规乳腺癌筛查的重要临床工具。基于背向散射信号分布的Nakagami参数图像在量化乳腺组织特性方面的功效最近被评估。B模式和Nakagami图像反映了乳腺肿瘤的不同物理特性：前者描述...

This paper presents a new algorithm for denoising dynamic contrast-enhanced (DCE) MR images. It is a novel variation on the nonlocal means (NLM) algorithm. The algorithm, called dynamic nonlocal means (DNLM), exploits the redundancy of information in the temporal sequence of images. Empirical evaluations of the performance of the DNLM algorithm relative to seven other denoising methods-simple Gaus...

本文提出了一种用于去噪动态对比增强（DCE）磁共振图像的新算法。这是非局部均值（NLM）算法的一种新颖变体。该算法称为动态非局部均值（DNLM），利用图像时间序列中的信息冗余。将DNLM算法与其他七种去噪方法（简单高斯滤波...）的性能进行实证评估...

Inkjet printing has been used to produce resonant radio frequency coils that are comparable to those produced by conventional printed circuit board (PCB) methods. The coils, which consist of a conductive loop and in-series capacitors, form part of a receiver circuit that is used for magnetic resonance imaging (MRI). The resonant circuit is selective at the predetermined frequency of 400 MHz. The r...

喷墨打印已被用于生产与常规印刷电路板（PCB）方法相当的谐振射频线圈。这些线圈由导电回路和串联电容器组成，是用于磁共振成像（MRI）的接收电路的一部分。谐振电路在预定的400 MHz频率下具有选择性。

Fluorescence molecular tomography (FMT) allows in vivo localization and quantification of fluorescence biodistributions in whole animals. The ill-posed nature of the tomographic reconstruction problem, however, limits the attainable resolution. Improvements in resolution and overall imaging performance can be achieved by forming image priors from geometric information obtained by a secondary anato...

荧光分子层析成像（FMT）能够在整个动物体内定位和定量荧光生物分布。然而，层析重建问题的不适定性限制了可达到的分辨率。通过从二次解剖...获取的几何信息形成图像先验，可以实现分辨率和整体成像性能的提升。

Intestinal motility assessment with video capsule endoscopy arises as a novel and challenging clinical fieldwork. This technique is based on the analysis of the patterns of intestinal contractions shown in a video provided by an ingestible capsule with a wireless micro-camera. The manual labeling of all the motility events requires large amount of time for offline screening in search of findings w...

视频胶囊内镜评估肠道动力是一项新颖且具有挑战性的临床工作。该技术基于分析由可吞服胶囊（内置无线微型摄像头）提供的视频中显示的肠收缩模式。手动标记所有动力事件需要大量时间进行离线筛选以寻找发现……

Since the introduction of 3-D rotational X-ray imaging, protocols for 3-D rotational coronary artery imaging have become widely available in routine clinical practice. Intra-procedural cardiac imaging in a computed tomography (CT)-like fashion has been particularly compelling due to the reduction of clinical overhead and ability to characterize anatomy at the time of intervention. We previously in...

自三维旋转X光成像问世以来，三维旋转冠状动脉成像的协议已在常规临床实践中广泛应用。术中心脏成像以类似计算机断层扫描（CT）的方式尤为引人注目，因为它减少了临床负担，并能在干预时描述解剖结构。我们之前...

Ultrasound elastography is now used worldwide in tissue characterization. The primary premises of elastography are that speckle kinematics reproduces underlying tissue kinematics and that tissue motion can be inferred from speckle tracking. This implicitly assumes that speckle pattern is a material property that can be tracked with respect to time and space. It is then convenient to express the mo...

超声弹性成像现在全球范围内用于组织表征。弹性成像的基本前提是斑点运动学再现了底层组织运动学，并且组织运动可以通过斑点跟踪推断。这隐含地假设斑点模式是一种材料属性，可以在时间和空间上进行跟踪。然后可以方便地表达...

Computer-aided detection (CAD) schemes are decision making support tools, useful to overcome limitations of problematic clinical procedures. Trans-rectal ultrasound image based CAD would be extremely important to support prostate cancer diagnosis. An effective approach to realize a CAD scheme for this purpose is described in this work, employing a multi-feature kernel classification model based on...

计算机辅助检测（CAD）方案是决策支持工具，有助于克服有问题的临床程序的局限性。基于经直肠超声图像的CAD对于支持前列腺癌诊断极为重要。本文描述了一种实现此目的的CAD方案的有效方法，采用基于...的多特征核分类模型。

This paper presents a procedure for automatic extraction and segmentation of a class-specific object (or region) by learning class-specific boundaries. We describe and evaluate the method with a specific focus on the detection of lesion regions in uterine cervix images. The watershed segmentation map of the input image is modeled using a Markov random field (MRF) in which watershed regions corresp...

本文介绍了一种通过学习类别特定边界来自动提取和分割类别特定对象（或区域）的程序。我们描述并评估了该方法，重点关注子宫颈图像中病变区域的检测。输入图像的 watershed 分割图使用马尔可夫随机场 (MRF) 建模，其中 watershed 区域对应...

The use of time-of-flight (TOF) information during positron emission tomography (PET) reconstruction has been found to improve the image quality. In this work we quantified this improvement using two existing methods: 1) a very simple analytical expression only valid for a central point in a large uniform disk source and 2) efficient analytical approximations for postfiltered maximum likelihood ex...

在正电子发射断层扫描（PET）重建过程中使用飞行时间（TOF）信息已被证明可以提高图像质量。在本工作中，我们使用两种现有方法量化了这一改进：1）一个非常简单的解析表达式，仅适用于大型均匀盘源的中心点；2）后滤波最大似然估计的高效解析近似。

During neurosurgery, nonrigid brain deformation prevents preoperatively-acquired images from accurately depicting the intraoperative brain. Stereo vision systems can be used to track intraoperative cortical surface deformation and update preoperative brain images in conjunction with a biomechanical model. However, these stereo systems are often plagued with calibration error, which can corrupt the...

在神经外科手术中，非刚性脑形变使得术前获取的图像无法准确描绘术中的大脑。立体视觉系统可用于跟踪术中皮层表面形变，并结合生物力学模型更新术前脑图像。然而，这些立体系统常常受到校准误差的困扰，这可能会破坏...

Nodule growth as observed in computed tomography (CT) scans acquired at different times is the primary feature to malignancy of indeterminate small lung nodules. In this paper, we propose the estimation of nodule size through a scale-space representation which needs no segmentation and has high intra- and inter-operator reproducibility. Lung nodules usually appear in CT images as blob-like pattern...

在不同时间获得的计算机断层扫描（CT）图像中观察到的结节生长是判断不确定小肺结节恶性的主要特征。本文提出通过尺度空间表示估计结节大小，该方法无需分割，且具有较高的操作者内和操作者间重复性。肺结节在CT图像中通常呈现为斑点状模式……

Detection of multiple lesions in images is a medically important task and free-response receiver operating characteristic (FROC) analyses and its variants, such as alternative FROC (AFROC) analyses, are commonly used to quantify performance in such tasks. However, ideal observers that optimize FROC or AFROC performance metrics have not yet been formulated in the general case. If available, such id...

在图像中检测多个病灶是一项医疗上的重要任务，而自由响应受试者工作特征（FROC）分析及其变体（如替代FROC（AFROC）分析）常用于量化此类任务的性能。然而，在一般情况下，优化FROC或AFROC性能指标的理想观察者尚未被提出。如果有这样的理想观察者，它们……

Interpolation is the means by which a continuously defined model is fit to discrete data samples. When the data samples are exempt of noise, it seems desirable to build the model by fitting them exactly. In medical imaging, where quality is of paramount importance, this ideal situation unfortunately does not occur. In this paper, we propose a scheme that improves on the quality by specifying a tra...

插值是将连续定义的模型拟合到离散数据样本的方法。当数据样本无噪声时，通过精确拟合来构建模型似乎是理想的。在医学成像中，质量至关重要，但不幸的是，这种理想情况并不存在。本文提出了一种通过指定...来提高质量的方案。