Volume 28, Issue 12

The noninvasive estimation of in vivo mechanical properties of cornea is envisioned to find several applications in ophthalmology. Such high-resolution measurements of local cornea stiffness could lead to a better anticipation and understanding of corneal pathologies such as Keratoconus. It could also provide a quantitative evaluation of corneal biomechanical response after corneal refractive surgeries and a tool for evaluating the efficacy of new cornea treatments such as cornea transplant using femtosecond laser or therapy based on Riboflavin/UltraViolet-A Corneal Cross Linking (UVA CXL). In the very important issue of glaucoma diagnosis and management, the fine tuning corneal elasticity measurement could also succeed to strongly correlate the applanation tonometry with the "true" intra-ocular pressure (IOP). This initial investigation evaluates the ability of ultrafast and high-resolution ultrasonic systems to provide a real-time and quantitative mapping of corneal viscoelasticity. Quantitative elasticity maps were acquired ex vivo on porcine cornea using the supersonic shear imaging (SSI) technique. A conventional 15 MHz linear probe was used to perform conventional ultrasonic imaging of the cornea. A dedicated ultrasonic sequence combines the generation of a remote palpation in the cornea and ultrafast (20 000 frames/s) ultrasonic imaging of the resulting corneal displacements that evolve into a shear wave propagation whose local speed was directly linked to local elasticity. A quantitative high-resolution map (150 mum resolution) of local corneal elasticity can be provided by this dedicated sequence of ultrasonic insonifications. Quantitative maps of corneal elasticity were obtained on ex vivo freshly enucleated porcine corneas. In the cornea, a quite homogenous stiffness map was found with a 190 kPa +/ - 32 kPa mean elasticity. The influence of photodynamic Riboflavin/UVA induced CXL was measured. A significant Young's modulus increase was obtained with a mean 890 kPa + / - 250 kPa posttreatment Young's modulus (460% increase), located in the anterior part of the cornea. Simulations based on 3-D time domain finite differences simulation were also performed and found to be in good agreement with ex vivo experiments. The SSI technique can perform real-time, noninvasive, high-resolution, and quantitative maps of the whole corneal elasticity. This technique could be real time and straightforward adapted for a very wide field of in vivo investigations.

对角膜体内力学特性的无创评估预计将在眼科领域有多个应用。这种对局部角膜刚度的高分辨率测量可以更好地预测和理解角膜病理，如圆锥角膜。它还可以为角膜屈光手术后角膜生物力学反应提供定量评估，并为评估新角膜治疗方法（如使用飞秒激光的角膜移植或基于核黄素/紫外线A角膜交联（UVA CXL）的治疗）的有效性提供工具。在青光眼诊断和管理的非常重要问题中，精细调节角膜弹性测量也可能成功地使压平式眼压计与“真实”眼内压（IOP）强相关。这项初步研究评估了超快速和高分辨率超声系统提供实时定量角膜粘弹性映射的能力。使用超音速剪切成像（SSI）技术在离体猪角膜上获取了定量弹性图。使用常规的15 MHz线性探头进行角膜的常规超声成像。专用的超声序列结合了角膜远程触诊的产生和超快速（20,000帧/秒）超声成像，跟踪演变为剪切波传播的角膜位移，其局部速度与局部弹性直接相关。通过这种专用的超声照射序列，可以提供局部角膜弹性的定量高分辨率图（150微米分辨率）。在离体新鲜摘除的猪角膜上获得了角膜弹性的定量图。在角膜中，发现了相当均匀的刚度图，平均弹性为190 kPa ± 32 kPa。测量了光动力核黄素/UVA诱导的CXL的影响。治疗后杨氏模量显著增加，平均为890 kPa ± 250 kPa（增加460%），位于角膜前部。还进行了基于3D时域有限差分的模拟，与离体实验吻合良好。SSI技术可以实时、无创、高分辨率地提供整个角膜弹性的定量图。该技术可以实时且直接适用于非常广泛的体内研究领域。

Lobe identification in computed tomography (CT) examinations is often an important consideration during the diagnostic process as well as during treatment planning because of their relative independence of each other in terms of anatomy and function. In this paper, we present a new automated scheme for segmenting lung lobes depicted on 3-D CT examinations. The unique characteristic of this scheme ...

在CT检查中，肺叶识别在诊断过程和治疗计划中常常是一个重要的考虑因素，因为它们在解剖和功能上相对独立。在本文中，我们提出了一种新的自动方案，用于分割3D CT检查中显示的肺叶。该方案的独特之处在于...

We report on a new quantification methodology of optoacoustic tomographic reconstructions under heterogeneous illumination conditions representative of realistic whole-body imaging scenarios. Our method relies on the differences in the spatial characteristics of the absorption coefficient and the optical energy density within the medium. By using sparse-representation based decomposition, we explo...

我们报道了一种新的光声断层重建定量方法，适用于代表真实全身成像场景的非均匀照明条件。我们的方法依赖于介质内吸收系数和光能密度的空间特性差异。通过使用基于稀疏表示的分解，我们探索...

In this paper, we propose the DT-REFinD algorithm for the diffeomorphic nonlinear registration of diffusion tensor images. Unlike scalar images, deforming tensor images requires choosing both a reorientation strategy and an interpolation scheme. Current diffusion tensor registration algorithms that use full tensor information face difficulties in computing the differential of the tensor reorientat...

本文提出用于扩散张量图像微分同胚非线性配准的DT-REFinD算法。与标量图像不同，变形张量图像需要同时选择重定向策略和插值方案。当前使用全张量信息的扩散张量配准算法在计算张量重定向的微分时面临困难……

When reading mammograms, radiologists do not only look at local properties of suspicious regions but also take into account more general contextual information. This suggests that context may be used to improve the performance of computer-aided detection (CAD) of malignant masses in mammograms. In this study, we developed a set of context features that represent suspiciousness of normal tissue in ...

在阅读乳腺X线摄影图像时，放射科医生不仅关注可疑区域的局部特征，还会考虑更广泛的背景信息。这表明，背景信息可能用于提高乳腺X线摄影中恶性肿块计算机辅助检测（CAD）的性能。在本研究中，我们开发了一组代表正常组织可疑程度的背景特征...

We propose to embed overlap priors in variational tracking of the left ventricle (LV) in cardiac magnetic resonance (MR) sequences. The method consists of evolving two curves toward the LV endo- and epicardium boundaries. We derive the curve evolution equations by minimizing two functionals each containing an original overlap prior constraint. The latter measures the conformity of the overlap betw...

我们提出在心脏磁共振（MR）序列的左心室（LV）变分追踪中嵌入重叠先验。该方法包括使两条曲线向LV内膜和外膜边界演化。我们通过最小化两个每个包含原始重叠先验约束的泛函来推导曲线演化方程。后者测量重叠的一致性...

A barrier to the adoption of non-Cartesian parallel magnetic resonance imaging for real-time applications has been the times required for the image reconstructions. These times have exceeded the underlying acquisition time thus preventing real-time display of the acquired images. We present a reconstruction algorithm for commodity graphics hardware (GPUs) to enable real time reconstruction of sens...

非笛卡尔并行磁共振成像在实时应用中的障碍之一是图像重建所需的时间。这些时间超过了底层采集时间，从而阻止了采集图像的实时显示。我们提出了一种用于商用图形硬件（GPU）的重建算法，以实现灵敏度的实时重建...

We have developed a general-purpose Monte Carlo simulation code, called penMesh, that combines the accuracy of the radiation transport physics subroutines from PENELOPE and the flexibility of a geometry based on triangle meshes. While the geometric models implemented in most general-purpose codes-such as PENELOPE's quadric geometry-impose some limitations in the shape of the objects that can be si...

我们开发了一个通用蒙特卡罗模拟代码，称为 penMesh，它结合了 PENELOPE 辐射输运物理子程序的准确性和基于三角网格的几何灵活性。大多数通用代码（如 PENELOPE 的二次曲面几何）中实现的几何模型在可模拟对象的形状方面施加了一些限制...

This paper describes a predictive and adaptive single parameter motion model for updating roadmaps to correct for respiratory motion in image-guided interventions. The model can adapt its motion estimates to respond to changes in breathing pattern, such as deep or fast breathing, which normally would result in a decrease in the accuracy of the motion estimates. The adaptation is made possible by i...

本文描述了一种用于更新路图以纠正图像引导干预中呼吸运动的预测性自适应单参数运动模型。该模型可以调整其运动估计以响应呼吸模式的变化，例如深呼吸或快速呼吸，这些变化通常会导致运动估计精度的下降。这种适应是通过...实现的。

A practical acceleration algorithm for real-time magnetic resonance imaging (MRI) is presented. Neither separate training scans nor embedded training samples are used. The Kalman filter based algorithm provides a fast and causal reconstruction of dynamic MRI acquisitions with arbitrary readout trajectories. The algorithm is tested against abrupt changes in the imaging conditions and offline recons...

提出了一种用于实时磁共振成像（MRI）的实用加速算法。该算法既不使用单独的扫描训练，也不使用嵌入的训练样本。基于卡尔曼滤波的算法能够对具有任意读出轨迹的动态MRI采集进行快速且因果的重建。该算法针对成像条件的突然变化和离线重建进行了测试。

Although Krylov subspace methods provide fast regularization techniques for the microwave imaging problem, they cannot preserve the edges of the object being imaged and may result in an oscillatory reconstruction. To suppress these spurious oscillations and to provide an edge-preserving regularization, we use a multiplicative regularizer which improves the reconstruction results significantly whil...

尽管Krylov子空间方法为微波成像问题提供了快速正则化技术，但它们无法保持成像对象的边缘，可能导致振荡重建。为了抑制这些虚假振荡并提供边缘保持正则化，我们使用乘法正则化器，这显著改善了重建结果，同时...

Comparing wrist shapes of different individuals requires alignment of these wrists into the same pose. Unconstrained registration of the carpal bones results in anatomically nonfeasible wrists. In this paper, we propose to constrain the registration using the shapes of adjacent bones, by keeping the width of the gap between adjacent bones constant. The registration is formulated as an optimization...

比较不同个体手腕形状需要将这些手腕对齐到相同的姿势。对手腕骨进行无约束配准会导致解剖学上不可行的手腕。本文提出利用相邻骨骼的形状约束配准，通过保持相邻骨骼间隙的宽度不变。配准被建模为一个优化问题...

Geometrical calibration is critical to obtaining high resolution and artifact-free reconstructed image for SPECT and CT systems. Most published calibration methods use analytical approach to determine the uniqueness condition for a specific calibration problem, and the calibration accuracy is often evaluated through empirical studies. In this work, we present a general method to assess the charact...

几何校准对于获得高分辨率和无伪影的SPECT和CT系统重建图像至关重要。大多数已发表的校准方法使用分析方法来确定特定校准问题的唯一性条件，而校准精度通常通过经验研究来评估。在这项工作中，我们提出了一种通用方法来评估表征...

The performance of a position sensitive gamma-ray scintillator detector (PSD) is described. This PSD is based on a lutetium yttrium oxyorthosilicate (LYSO) crystal read out by a crossed-wire anode position sensitive photomultiplier tube (PSPMT). The main difference with respect to similar existing devices is the individual multi-anode readout (IMAR) approach that is followed here. This method allo...

描述了一种位置灵敏γ射线闪烁体探测器（PSD）的性能。该PSD基于由交叉线阳极位置灵敏光电倍增管（PSPMT）读出的硅酸钇镥（LYSO）晶体。与现有类似设备的主要区别在于本文采用的独立多阳极读出（IMAR）方法。该方法允许...

Intraoperative dosimetry in prostate brachytherapy requires localization of the implanted radioactive seeds. A tomosynthesis-based seed reconstruction method is proposed. A three-dimensional volume is reconstructed from Gaussian-blurred projection images and candidate seed locations are computed from the reconstructed volume. A false positive seed removal process, formulated as an optimal coverage...

前列腺近距离治疗中的术中剂量测定需要定位植入的放射性种子。提出了一种基于断层合成的种子重建方法。从高斯模糊的投影图像重建三维体积，并从重建的体积中计算出候选种子位置。假阳性种子去除过程被公式化为一个最优覆盖问题...

Electrophysiological cardiac data mapping is an essential tool for the study of cardiac rhythm disorders, such as atrial fibrillation. Over the past decade, various advanced cardiac mapping systems have been developed to create detailed cardiac maps and assist physicians in diagnosis and therapy guidance. While these systems have increased the ability to study and treat cardiac arrhythmias, inhere...

心脏电生理数据映射是研究心律失常（如心房颤动）的重要工具。过去十年中，各种先进的心脏映射系统已被开发出来，用于创建详细的心脏图谱并协助医生进行诊断和治疗指导。虽然这些系统提高了研究和治疗心律失常的能力，但仍存在...

Separating bone, calcification, and vessels in computer tomography angiography (CTA) allows for a detailed diagnosis of vessel stenosis. This paper presents a new, graph-based technique that solves this difficult problem with high accuracy. The approach requires one native data set and one that is contrast enhanced. On each data set, an attributed level-graph is derived and both graphs are matched...

在计算机断层血管造影（CTA）中分离骨骼、钙化和血管，可以实现对血管狭窄的详细诊断。本文提出了一种新的基于图的技术，可以高精度地解决这一难题。该方法需要一个原生数据集和一个对比增强数据集。在每个数据集上，推导出一个带属性的层次图，并将两个图进行匹配...

We analyze some relationships between the small- and smooth-phase conditions in propagation-based X-ray phase-contrast imaging. Although these conditions are generally well-understood, our analysis yields the identification of physical conditions under which they are mathematically equivalent. We also demonstrate that the smooth-phase condition depends not only on the imaging system resolution and...

我们分析了基于传播的X射线相位衬度成像中小相位条件与平滑相位条件之间的一些关系。尽管这些条件通常被很好地理解，但我们的分析发现了它们在数学上等效的物理条件。我们还证明了平滑相位条件不仅取决于成像系统的分辨率以及...

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被评论或更正的条目。如果部门和其他项目被认为具有档案价值，也可能被涵盖。作者索引包含每个项目的主要条目，列在第一作者名下……

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

提供当前工作人员、委员会成员及学会官员的名单。

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

为希望提交稿件的潜在作者提供说明和指南。

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

呈现本期期刊的目录。