Volume 28, Issue 11

In radial fast spin-echo magnetic resonance imaging (MRI), a set of overlapping spokes with an inconsistent T2 weighting is acquired, which results in an averaged image contrast when employing conventional image reconstruction techniques. This work demonstrates that the problem may be overcome with the use of a dedicated reconstruction method that further allows for T2 quantification by extracting the embedded relaxation information. Thus, the proposed reconstruction method directly yields a spin-density and relaxivity map from only a single radial data set. The method is based on an inverse formulation of the problem and involves a modeling of the received MRI signal. Because the solution is found by numerical optimization, the approach exploits all data acquired. Further, it handles multicoil data and optionally allows for the incorporation of additional prior knowledge. Simulations and experimental results for a phantom and human brain in vivo demonstrate that the method yields spin-density and relaxivity maps that are neither affected by the typical artifacts from TE mixing, nor by streaking artifacts from the incomplete k-space coverage at individual echo times.

在径向快速自旋回波磁共振成像中，采集一组具有不一致T2加权的重叠径向线，当采用常规图像重建技术时会导致平均图像对比度。本研究表明，通过使用专用的重建方法可以克服该问题，该方法还通过提取嵌入的弛豫信息实现T2定量。因此，所提出的重建方法直接从单个径向数据集生成自旋密度图和弛豫率图。该方法基于问题的逆公式化，并涉及接收到的MRI信号的建模。由于通过数值优化求解，该方法利用了所有采集到的数据。此外，它处理多线圈数据，并可选地允许纳入额外的先验知识。对体模和活体人脑的模拟和实验结果表明，该方法生成的自旋密度图和弛豫率图既不受典型的TE混合伪影影响，也不受单个回波时间k空间覆盖不完全引起的条纹伪影影响。

Indirect and direct methods have been developed for reconstructing parametric images from dynamic positron emission tomography (PET) data. Indirect methods are simple and easy to implement because reconstruction and kinetic modeling are performed in two separate steps. Direct methods estimate parametric images directly from dynamic PET sinograms and, in theory, can be statistically more efficient,...

间接和直接方法已被开发用于从动态正电子发射断层扫描（PET）数据重建参数图像。间接方法简单易实现，因为重建和动力学建模分两步进行。直接方法直接从动态PET正弦图估计参数图像，理论上统计效率更高，...

We present the first in vivo cross-sectional conductivity image of the human leg with 1.7 mm pixel size using the magnetic resonance electrical impedance tomography (MREIT) technique. After a review of its experimental protocol by an Institutional Review Board (IRB), we performed MREIT imaging experiments of four human subjects using a 3 T MRI scanner. Adopting thin and flexible carbon-hydrogel el...

我们展示了首次使用磁共振电阻抗断层成像（MREIT）技术获得的人体腿部在体横截面电导率图像，像素大小为1.7毫米。在机构审查委员会（IRB）审查其实验方案后，我们使用3T MRI扫描仪对四名人体受试者进行了MREIT成像实验。采用薄而灵活的碳-水凝胶电极...

Dual-energy (DE) X-ray computed tomography (CT) has been found useful in various applications. In medical imaging, one promising application is using low-dose DECT for attenuation correction in positron emission tomography (PET). Existing approaches to sinogram material decomposition ignore noise characteristics and are based on logarithmic transforms, producing noisy component sinogram estimates ...

双能X射线计算机断层扫描（CT）在各种应用中被证明是有用的。在医学成像中，一个很有前景的应用是使用低剂量双能CT进行正电子发射断层扫描（PET）的衰减校正。现有的正弦图材料分解方法忽略了噪声特性，且基于对数变换，导致产生噪声分量正弦图估计。

In the classic formulation of photoacoustic tomography (PAT), two distinct descriptions of the imaging model have been employed for developing reconstruction algorithms. We demonstrate that the numerical and statistical properties of unweighted least-squares reconstruction algorithms associated with each imaging model are generally very different. Specifically, some PAT reconstruction algorithms, ...

在经典的光声断层成像（PAT）公式中，使用了两种不同的成像模型描述来开发重建算法。我们证明了与每个成像模型相关的无权重最小二乘重建算法的数值和统计特性通常非常不同。具体来说，一些PAT重建算法，...

Although it is accepted that linear Granger causality can reveal effective connectivity in functional magnetic resonance imaging (fMRI), the issue of detecting nonlinear connectivity has hitherto not been considered. In this paper, we address kernel Granger causality (KGC) to describe effective connectivity in simulation studies and real fMRI data of a motor imagery task. Based on the theory of re...

尽管线性格兰杰因果关系可以揭示功能磁共振成像（fMRI）中的有效连接，但检测非线性连接的问题迄今尚未被考虑。本文中，我们采用核格兰杰因果关系（KGC）来描述模拟研究和实际运动想象任务fMRI数据中的有效连接。基于重...

Generating 3-D images of the heart during interventional procedures is a significant challenge. In addition to real time fluoroscopy, angiographic C-arm systems can also now be used to generate 3-D/4-D CT images on the same system. One protocol for cardiac CT uses ECG triggered multisweep scans. A 3-D volume of the heart at a particular cardiac phase is then reconstructed by applying Feldkamp (FDK...

在介入手术过程中生成心脏的三维图像是一个重大挑战。除了实时透视外，血管造影C型臂系统现在也可用于在同一系统上生成3D/4D CT图像。心脏CT的一种协议使用ECG触发的多扫描扫描。然后通过应用Feldkamp（FDK...）重建特定心脏相位的心脏三维体积。

This paper presents an algorithm for fast image synthesis inside deformed volumes. Given the node displacements of a mesh and a reference 3-D image dataset of a predeformed volume, the method first maps the image pixels that need to be synthesized from the deformed configuration to the nominal predeformed configuration, where the pixel intensities are obtained easily through interpolation in the r...

本文提出了一种在变形体积内快速图像合成的算法。给定网格的节点位移和变形前体积的参考三维图像数据集，该方法首先将需要从变形配置合成的图像像素映射到标称的变形前配置，其中像素强度通过参考图像数据集中的插值获得。

Fourier reconstruction algorithms significantly outperform conventional backprojection algorithms in terms of computation time. In photoacoustic imaging, these methods require interpolation in the Fourier space domain, which creates artifacts in reconstructed images. We propose a novel reconstruction algorithm that applies the one-dimensional nonuniform fast Fourier transform to photoacoustic imag...

傅里叶重建算法在计算时间上显著优于传统的反投影算法。在光声成像中，这些方法需要在傅里叶空间域进行插值，这会在重建图像中产生伪影。我们提出了一种新的重建算法，该算法将一维非均匀快速傅里叶变换应用于光声成像...

Dynamic cardiac magnetic resonance imaging (MR) and computed tomography (CT) provide cardiologists and cardiac surgeons with high-quality 4-D images for diagnosis and therapy, yet the effective use of these high-quality anatomical models remains a challenge. Ultrasound (US) is a flexible imaging tool, but the US images produced are often difficult to interpret unless they are placed within their p...

动态心脏磁共振成像（MR）和计算机断层扫描（CT）为心脏病专家和心脏外科医生提供高质量的4D图像用于诊断和治疗，然而，这些高质量解剖模型的有效使用仍然是一个挑战。超声（US）是一种灵活的成像工具，但产生的US图像通常难以解读，除非将它们置于其背景中...

Uncertainties in image registration may be a significant source of errors in anatomy mapping as well as dose accumulation in radiotherapy. It is, therefore, essential to validate the accuracy of image registration. Here, we propose a method to detect areas where mono modal B-spline registration performs well and to distinguish those from areas of the same image, where the registration is likely to...

图像配准中的不确定性可能是解剖映射以及放射治疗中剂量累积的重要误差来源。因此，验证图像配准的准确性至关重要。在这里，我们提出了一种方法来检测单模态B样条配准表现良好的区域，并将其与同一图像中配准可能...的区域区分开来。

In fundus photography, the task of fine focusing the image is demanding and lack of focus is quite often the cause of suboptimal photographs. The introduction of digital cameras has provided an opportunity to automate the task of focusing. We have developed a software algorithm capable of identifying best focus. The auto-focus (AF) method is based on an algorithm we developed to assess the sharpne...

在眼底摄影中，精细对焦是一项要求高且常常因对焦不准导致图像质量不佳的任务。数码相机的引入为实现自动对焦提供了机会。我们开发了一种能够识别最佳对焦的软件算法。自动对焦方法基于我们开发的评估图像锐度的算法……

The use of selective internal radiation therapy for treatment of hepatocellular carcinoma and liver metastases using Y-90 labeled microspheres has become an effective and widely used treatment regimen. However, dosimetric evaluations of this treatment are still primitive as uniform distribution models based only on injected activity are often used. This investigation attempts to quantify the effec...

使用Y-90标记微球的选择性内放射疗法治疗肝细胞癌和肝转移瘤已成为一种有效且广泛应用的治疗方案。然而，该治疗的剂量学评估仍然较为原始，因为通常仅基于注射活度的均匀分布模型。本研究试图量化...

Automated analysis of mammograms requires robust methods for pectoralis segmentation and nipple detection. Locating the nipple is especially important in multiview computer aided detection systems, in which findings are matched across images using the nipple-to-finding distance. Segmenting the pectoralis is a key preprocessing step to avoid false positives when detecting masses due to the similari...

乳腺X线照片的自动化分析需要稳健的胸肌分割和乳头检测方法。在多视角计算机辅助检测系统中，乳头定位尤为重要，因为系统通过乳头到病灶的距离来匹配不同图像中的发现。胸肌分割是关键预处理步骤，以避免因相似性而在检测肿块时产生假阳性。

Tissue biomechanical properties (like strain and stress) are playing an increasing role in diagnosis and long-term treatment of intravascular coronary diseases. Their assessment strongly relies on estimation of vessel wall deformation. Since intravascular ultrasound (IVUS) sequences allow visualizing vessel morphology and reflect its dynamics, this technique represents a useful tool for evaluation...

组织生物力学特性（如应变和应力）在冠状动脉疾病的诊断和长期治疗中发挥着越来越重要的作用。它们的评估强烈依赖于血管壁变形的估计。由于血管内超声（IVUS）序列能够可视化血管形态并反映其动态，该技术成为评估的有用工具…

Rigid-body point-based registration is frequently used in computer assisted surgery to align corresponding points, or fiducials, in preoperative and intraoperative data. This alignment is mostly achieved by assuming the same homogeneous error distribution for all the points; however, due to the properties of the medical instruments used in measuring the point coordinates, the error distribution mi...

刚体点配准常用于计算机辅助手术中，以对齐术前和术内数据中的对应点或基准。这种对齐通常通过假设所有点具有相同的均匀误差分布来实现；然而，由于测量点坐标所使用的医疗仪器的特性，误差分布可能会...

Motion during diffusion encodings leads to different phase errors in different shots of multishot diffusion-weighted acquisitions. Phase error incoherence among shots results in undesired signal cancellation when data from all shots are combined. Motion-induced phase error correction for multishot diffusion-weighted imaging (DWI) has been studied extensively and there exist multiple phase error co...

在扩散编码过程中，运动会导致多次激励扩散加权采集的不同激励之间产生不同的相位误差。激励间的相位误差不一致会导致当所有激励的数据组合时出现不必要的信号抵消。针对多次激励扩散加权成像（DWI）中运动引起的相位误差校正已被广泛研究，存在多种相位误差补偿方法...

Susceptibility-induced distortion is one of the major artifacts in echo-planar imaging (EPI), and many solutions have been proposed for the problem, including the Fourier method and the point spread function (PSF) method. In this paper, a framework unifying both methods is presented. Under this framework, a model-based PSF method is proposed in which the PSF of the source object is modeled along w...

磁敏感伪影引起的失真是回波平面成像（EPI）中的主要伪影之一，目前已提出了多种解决方案，包括傅里叶方法和点扩散函数（PSF）方法。本文提出了一个统一这两种方法的框架。在该框架下，提出了一种基于模型的PSF方法，其中源对象的PSF沿着...建模

This paper proposes a new distortion model for strong inhomogeneity problems in echo planar imaging (EPI). Fast imaging sequences in magnetic resonance imaging (MRI), such as EPI, are very important in applications where temporal resolution or short total acquisition time is essential. Unfortunately, fast imaging sequences are very sensitive to variations in the homogeneity of the main magnetic fi...

本文提出了一种用于回波平面成像（EPI）中强不均匀性问题的新畸变模型。磁共振成像（MRI）中的快速成像序列，如EPI，在时间分辨率或短总采集时间至关重要的应用中非常重要。不幸的是，快速成像序列对主磁场均匀性的变化非常敏感...

Provides notice of upcoming special issue(s) of interest to practitioners and researchers.

为从业者和研究人员提供即将到来的特刊通知。

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

为有意投稿的作者提供指南和说明。

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

诚邀有意投稿的作者提交新的、未发表的手稿，以收录在本征文启事中所述的即将举行的活动中。

Provides a listing of current staff, committee members and society officers.

提供现任员工、委员会成员学会官员的名单。

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广告：探索IEL IEEE最全面的资源。

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

呈现本期刊物的目录。