Volume 28, Issue 10

Automatic extraction of vertebra regions from a spinal magnetic resonance (MR) image is normally required as the first step to an intelligent spinal MR image diagnosis system. In this work, we develop a fully automatic vertebra detection and segmentation system, which consists of three stages; namely, AdaBoost-based vertebra detection, detection refinement via robust curve fitting, and vertebra segmentation by an iterative normalized cut algorithm. In order to produce an efficient and effective vertebra detector, a statistical learning approach based on an improved AdaBoost algorithm is proposed. A robust estimation procedure is applied on the detected vertebra locations to fit a spine curve, thus refining the above vertebra detection results. This refinement process involves removing the false detections and recovering the miss-detected vertebrae. Finally, an iterative normalized-cut segmentation algorithm is proposed to segment the precise vertebra regions from the detected vertebra locations. In our implementation, the proposed AdaBoost-based detector is trained from 22 spinal MR volume images. The experimental results show that the proposed vertebra detection and segmentation system can achieve nearly 98% vertebra detection rate and 96% segmentation accuracy on a variety of testing spinal MR images. Our experiments also show the vertebra detection and segmentation accuracies by using the proposed algorithm are superior to those of the previous representative methods. The proposed vertebra detection and segmentation system is proved to be robust and accurate so that it can be used for advanced research and application on spinal MR images.

从脊柱磁共振（MR）图像中自动提取椎骨区域通常是智能脊柱MR图像诊断系统的第一步。本文开发了一个全自动的椎骨检测与分割系统，包括三个阶段：基于AdaBoost的椎骨检测、通过鲁棒曲线拟合的检测精化，以及通过迭代归一化切割算法的椎骨分割。为了产生高效且有效的椎骨检测器，提出了一种基于改进AdaBoost算法的统计学习方法。对检测到的椎骨位置应用鲁棒估计过程以拟合脊柱曲线，从而精化上述椎骨检测结果。该精化过程包括去除假阳性检测和恢复漏检的椎骨。最后，提出了一种迭代归一化切割分割算法，以从检测到的椎骨位置中分割出精确的椎骨区域。在我们的实现中，所提出的基于AdaBoost的检测器使用22个脊柱MR容积图像进行训练。实验结果表明，所提出的椎骨检测与分割系统在多种测试脊柱MR图像上可实现近98%的椎骨检测率和96%的分割准确率。我们的实验还表明，使用所提出算法的椎骨检测和分割准确率优于以往代表性方法。所提出的椎骨检测与分割系统被证明是鲁棒且准确的，因此可用于脊柱MR图像的高级研究和应用。

Noise filtering techniques that maintain image contrast while decreasing image noise have the potential to optimize the quality of computed tomography (CT) images acquired at reduced radiation dose. In this paper, a hybrid diffusion filter with continuous switch (HDCS) is introduced, which exploits the benefits of three-dimensional edge-enhancing diffusion (EED) and coherence-enhancing diffusion (...

在降低辐射剂量下获取的计算机断层扫描（CT）图像中，保持图像对比度同时降低图像噪声的噪声滤波技术具有优化图像质量的潜力。本文介绍了一种具有连续切换的混合扩散滤波器（HDCS），它利用了三维边缘增强扩散（EED）和相干增强扩散的优势...

Respiratory motion is a major concern in cone-beam (CB) computed tomography (CT) of the thorax. It causes artifacts such as blur, streaks, and bands, in particular when using slow-rotating scanners mounted on the gantry of linear accelerators. In this paper, we compare two approaches for motion-compensated CBCT reconstruction of the thorax. The first one is analytic; it is heuristically adapted fr...

呼吸运动是胸部锥束计算机断层扫描（CBCT）中的一个主要问题。它会导致模糊、条纹和条带等伪影，尤其是在使用安装在直线加速器机架上的慢速旋转扫描仪时。本文比较了两种用于胸部运动补偿CBCT重建的方法。第一种是解析方法，它通过启发式算法适应...

Large-tip-angle multidimensional radio-frequency (RF) pulse design is a difficult problem, due to the nonlinear response of magnetization to applied RF at large tip-angles. In parallel excitation, multidimensional RF pulse design is further complicated by the possibility for transmit field patterns to change between subjects, requiring pulses to be designed rapidly while a subject lies in the scan...

大翻转角多维射频（RF）脉冲设计是一个难题，因为在大翻转角下磁化对施加RF的响应是非线性的。在并行激励中，由于发射场模式可能在不同受试者之间变化，需要受试者在扫描过程中快速设计脉冲，这使得多维RF脉冲设计更加复杂。

Although real imaging problems involve objects that have variations in three dimensions, a majority of work examining inverse scattering methods for ultrasonic tomography considers 2-D imaging problems. Therefore, the study of 3-D inverse scattering methods is necessary for future applications of ultrasonic tomography. In this work, 3-D reconstructions using different arrays of rectangular element...

尽管实际成像问题涉及具有三维变化的物体，但大多数研究超声层析成像逆散射方法的工作都考虑二维成像问题。因此，研究三维逆散射方法对于超声层析成像的未来应用是必要的。在这项工作中，使用不同的矩形元件阵列进行三维重建...

Delayed enhancement MRI (DE-MRI) can be used to identify myocardial infarct (MI). Classification of MI into the infarct core and heterogeneous periphery (called the gray zone) on conventional inversion-recovery gradient echo (IR-GRE) DE-MRI images has been related to inducibility for ventricular tachycardia. However, this classification is sensitive to image noise, depends on the signal intensity ...

延迟增强磁共振成像（DE-MRI）可用于识别心肌梗死（MI）。在传统的反转恢复梯度回波（IR-GRE）DE-MRI图像上，将MI分类为梗死核心和异质性周边（称为灰色区域）与室性心动过速的诱发性相关。然而，这种分类对图像噪声敏感，依赖于信号强度...

The D-bar algorithm based on Nachman's 2-D global uniqueness proof for the inverse conductivity problem (Nachman, 1996) is implemented on a chest-shaped domain. The scattering transform is computed on this chest-shaped domain using trigonometric and adjacent current patterns and the complete electrode model for the forward problem is computed with the finite element method in order to obtain simul...

基于Nachman（1996）关于逆电导率问题的二维全局唯一性证明的D-bar算法在胸形域上实现。使用三角和相邻电流模式在该胸形域上计算散射变换，并使用有限元方法计算正问题的完整电极模型，以获得模拟...

Dynamic contrast-enhanced magnetic resonance (DCE-MR) imaging can be used to study microvascular structure in vivo by monitoring the abundance of an injected diffusible contrast agent over time. The resulting spatially resolved intensity-time curves are usually interpreted in terms of kinetic parameters obtained by fitting a pharmacokinetic model to the observed data. Least squares estimates of th...

动态对比增强磁共振（DCE-MR）成像可通过监测注入的可扩散对比剂随时间的变化来研究体内微血管结构。由此产生的空间分辨强度-时间曲线通常通过将药代动力学模型拟合到观测数据来获得动力学参数来解释。最小二乘估计...

Magnetic resonance elastography (MRE) is an imaging modality capable of visualizing the elastic properties of an object using magnetic resonance imaging (MRI) measurements of transverse acoustic strain waves induced in the object by a harmonically oscillating mechanical vibration. Various algorithms have been designed to determine the mechanical properties of the object under the assumptions of li...

磁共振弹性成像是利用磁共振成像测量由谐波振荡机械振动在物体中诱发的横向声应变波，从而可视化物体弹性特性的成像模态。已设计了多种算法在假定...下确定物体的力学特性。

Estimating the noise parameter in magnitude magnetic resonance (MR) images is important in a wide range of applications. We propose an automatic noise estimation method that does not rely on a substantial proportion of voxels being from the background. Specifically, we model the magnitude of the observed signal as a mixture of Rice distributions with common noise parameter. The expectation-maximiz...

在幅度磁共振（MR）图像中估计噪声参数在许多应用中都很重要。我们提出了一种自动噪声估计方法，该方法不依赖于大量体素来自背景。具体来说，我们将观测信号的幅度建模为具有共同噪声参数的Rice分布的混合。期望最大化...

Currently, conventional X-ray and CT images as well as invasive methods performed during the surgical intervention are used to judge the local quality of a fractured proximal femur. However, these approaches are either dependent on the surgeon's experience or cannot assist diagnostic and planning tasks preoperatively. Therefore, in this work a method for the individual analysis of local bone quali...

目前，传统的X射线和CT图像以及手术过程中进行的侵入性方法被用于判断骨折股骨近端的局部质量。然而，这些方法要么依赖于外科医生的经验，要么无法在术前辅助诊断和规划任务。因此，在这项工作中，提出了一种用于个体化分析局部骨质量的方法。

We present an approach to skeletal muscle contractility and its regulation over different scales ranging from biomechanical studies in intact muscle fibers down to the motility and interaction of single motor protein molecules. At each scale, shortening velocities as a measure for weak cross-bridge cycling rates are extracted and compared. Experimental approaches include transmitted light microsco...

我们提出了一种研究骨骼肌收缩性及其在不同尺度上调控的方法，范围从完整肌纤维的生物力学研究到单个运动蛋白分子的运动性和相互作用。在每个尺度上，提取并比较缩短速度作为弱横桥循环速率的度量。实验方法包括透射光显微镜...

Detection of small lesions in fluorodeoxyglucose (FDG) positron emission tomography (PET) is limited by image resolution and low signal to noise ratio. We have previously described a matched subspace detection method that uses the time activity curve to distinguish tumors from background in dynamic FDG PET. Applying this algorithm on a voxel by voxel basis throughout the dynamic image produces a t...

在氟代脱氧葡萄糖（FDG）正电子发射断层扫描（PET）中，小病灶的检测受到图像分辨率和低信噪比的限制。我们之前描述了一种匹配子空间检测方法，该方法利用时间活度曲线区分动态FDG PET中的肿瘤与背景。在动态图像的每个体素上应用该算法会生成一个t...

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提供当前工作人员、委员会成员及学会官员的列表。

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

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介绍本期期刊的目录。

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