Volume 30, Issue 9

Automatic whole-brain extraction from magnetic resonance images (MRI), also known as skull stripping, is a key component in most neuroimage pipelines. As the first element in the chain, its robustness is critical for the overall performance of the system. Many skull stripping methods have been proposed, but the problem is not considered to be completely solved yet. Many systems in the literature have good performance on certain datasets (mostly the datasets they were trained/tuned on), but fail to produce satisfactory results when the acquisition conditions or study populations are different. In this paper we introduce a robust, learning-based brain extraction system (ROBEX). The method combines a discriminative and a generative model to achieve the final result. The discriminative model is a Random Forest classifier trained to detect the brain boundary; the generative model is a point distribution model that ensures that the result is plausible. When a new image is presented to the system, the generative model is explored to find the contour with highest likelihood according to the discriminative model. Because the target shape is in general not perfectly represented by the generative model, the contour is refined using graph cuts to obtain the final segmentation. Both models were trained using 92 scans from a proprietary dataset but they achieve a high degree of robustness on a variety of other datasets. ROBEX was compared with six other popular, publicly available methods (BET, BSE, FreeSurfer, AFNI, BridgeBurner, and GCUT) on three publicly available datasets (IBSR, LPBA40, and OASIS, 137 scans in total) that include a wide range of acquisition hardware and a highly variable population (different age groups, healthy/diseased). The results show that ROBEX provides significantly improved performance measures for almost every method/dataset combination.

从磁共振图像（MRI）中进行全自动全脑提取（也称为颅骨剥离）是大多数神经影像处理流程中的关键组成部分。作为流程中的第一步，其鲁棒性对整个系统的性能至关重要。尽管已有许多颅骨剥离方法被提出，但该问题尚未被认为得到完全解决。文献中的许多系统在特定数据集（通常是它们训练/调整所用的数据集）上表现良好，但当采集条件或研究对象群体不同时，却无法产生令人满意的结果。本文介绍了一种鲁棒的、基于学习的脑提取系统（ROBEX）。该方法结合了判别模型和生成模型以获得最终结果。判别模型是一个随机森林分类器，用于检测脑边界；生成模型是一个点分布模型，确保结果的合理性。当新图像输入系统时，生成模型被探索以找到根据判别模型具有最高可能性的轮廓。由于生成模型通常不能完美表示目标形状，因此使用图割对轮廓进行细化以获得最终分割。两个模型均使用来自专有数据集的92次扫描进行训练，但在各种其他数据集上实现了高度的鲁棒性。将ROBEX与六种其他流行的公开可用方法（BET、BSE、FreeSurfer、AFNI、BridgeBurner和GCUT）在三个公开数据集（IBSR、LPBA40和OASIS，共137次扫描）上进行了比较，这些数据集包含广泛的采集硬件和高度可变的人群（不同年龄组、健康/患病）。结果表明，对于几乎每个方法/数据集组合，ROBEX都提供了显著改进的性能指标。

Magnetic particle imaging (MPI) is a promising new medical imaging tracer modality with potential applications in human angiography, cancer imaging, in vivo cell tracking, and inflammation imaging. Here we demonstrate both theoretically and experimentally that multidimensional MPI is a linear shift-invariant imaging system with an analytic point spread function. We also introduce a fast image reco...

磁粒子成像（MPI）是一种前景广阔的新型医学影像示踪剂模态，在人体血管造影、癌症成像、体内细胞追踪和炎症成像方面具有潜在应用。这里我们从理论和实验两方面证明，多维MPI是一种线性平移不变成像系统，具有解析点扩散函数。我们还介绍了一种快速的图像重建方法。

For quantitative analysis of histopathological images, such as the lymphoma grading systems, quantification of features is usually carried out on single cells before categorizing them by classification algorithms. To this end, we propose an integrated framework consisting of a novel supervised cell-image segmentation algorithm and a new touching-cell splitting method. For the segmentation part, we...

对于组织病理学图像的定量分析，例如淋巴瘤分级系统，特征量化通常在单个细胞上进行，然后通过分类算法对其进行分类。为此，我们提出了一个集成框架，包括一种新颖的监督细胞图像分割算法和一种新的接触细胞分裂方法。对于分割部分，我们……

In this work, we exploit the fact that wavelets can represent magnetic resonance images well, with relatively few coefficients. We use this property to improve magnetic resonance imaging (MRI) reconstructions from undersampled data with arbitrary k-space trajectories. Reconstruction is posed as an optimization problem that could be solved with the iterative shrinkage/thresholding algorithm (ISTA) ...

在本工作中，我们利用小波可以用相对较少的系数很好地表示磁共振图像这一事实。我们利用这一特性来改善从任意k空间轨迹的欠采样数据中进行的磁共振成像（MRI）重建。重建被表述为一个优化问题，可以通过迭代收缩/阈值算法（ISTA）求解……

The feasibility of K-edge imaging using energy-resolved, photon-counting transmission measurements in X-ray computed tomography (CT) has been demonstrated by simulations and experiments. The method is based on probing the discontinuities of the attenuation coefficient of heavy elements above and below the K-edge energy by using energy-sensitive, photon counting X-ray detectors. In this paper, we i...

通过仿真和实验，已经证明了利用能量分辨光子计数透射测量在X射线计算机断层扫描（CT）中进行K边缘成像的可行性。该方法基于使用能量敏感的光子计数X射线探测器，探测重元素的衰减系数在K边缘能量以上和以下的不连续性。在本文中，我们...

Cardiac remodelling plays a crucial role in heart diseases. Analyzing how the heart grows and remodels over time can provide precious insights into pathological mechanisms, eventually resulting in quantitative metrics for disease evaluation and therapy planning. This study aims to quantify the regional impacts of valve regurgitation and heart growth upon the end-diastolic right ventricle (RV) in p...

心脏重塑在心脏疾病中起着关键作用。分析心脏随时间生长和重塑的过程可以为病理机制提供宝贵的见解，最终得出用于疾病评估和治疗规划的定量指标。本研究旨在量化瓣膜反流和心脏生长对...的舒张末期右心室（RV）的区域影响。

The 3-D morphology of chicken articular cartilage was quantified using multiphoton microscopy (MPM) for use in continuum-mechanical modeling. To motivate this morphological study we propose aspects of a new, 3-D finite strain constitutive model for articular cartilage focusing on the essential load-bearing morphology: an inhomogeneous, poro-(visco)elastic solid matrix reinforced by an anisotropic,...

使用多光子显微镜（MPM）对鸡关节软骨的三维形态进行量化，以用于连续介质力学建模。为激发这项形态学研究，我们提出了一种新的三维有限应变本构模型的各个方面，该模型针对关节软骨的主要承重形态：一个由各向异性增强的非均匀、多孔（粘）弹性固体基质...

A common solution to clinical MR imaging in the presence of large anatomical motion is to use fast multislice 2D studies to reduce slice acquisition time and provide clinically usable slice data. Recently, techniques have been developed which retrospectively correct large scale 3D motion between individual slices allowing the formation of a geometrically correct 3D volume from the multiple slice s...

在存在较大解剖运动的情况下，临床MR成像的常见解决方案是使用快速多切片2D研究以减少切片采集时间并提供临床可用的切片数据。最近，已经开发了技术，可以回顾性地纠正单个切片之间的大规模3D运动，从而从多个切片中形成几何正确的3D体积...

Dynamic fluorescence diffuse optical tomography (D-FDOT) is important for drug delivery research. However, the low spatial resolution of FDOT and the complex kinetics of drug limit the ability of D-FDOT in resolving metabolic processes of drug throughout whole body of small animals. In this paper, we propose an independent component analysis (ICA)-based method to perform D-FDOT studies. When appli...

动态荧光扩散光学断层成像（D-FDOT）在药物递送研究中具有重要意义。然而，FDOT的低空间分辨率和药物的复杂动力学限制了D-FDOT解析小动物全身药物代谢过程的能力。本文提出了一种基于独立成分分析（ICA）的方法来进行D-FDOT研究。当应用...

Reduced order modelling, in which a full system response is projected onto a subspace of lower dimensionality, has been used previously to accelerate finite element solution schemes by reducing the size of the involved linear systems. In the present work we take advantage of a secondary effect of such reduction for explicit analyses, namely that the stable integration time step is increased far be...

降阶建模将完整系统响应投影到低维子空间，此前已被用于通过减少相关线性系统的规模来加速有限元求解方案。在本工作中，我们利用了这种降阶对显式分析的次要效应，即稳定积分时间步长大大增加

Blood oxygenation level dependent (BOLD) contrast in functional magnetic resonance imaging (fMRI) can be enhanced using multi-echo imaging and postprocessing techniques that combine the echoes in weighted summation. Here, existing echo-weighting methods are reassessed in the context of an explicit physiological noise model, and a new method is introduced: weights that scale linearly with echo time...

在功能磁共振成像（fMRI）中，可以通过多回波成像和后处理技术（如加权求和结合回波）来增强血氧水平依赖（BOLD）对比度。本文在明确的生理噪声模型背景下重新评估了现有的回波加权方法，并提出了一种新方法：权重与回波时间成线性比例。

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

提供即将出版的特刊通知，供从业者和研究人员参考。

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

提供当前员工、委员会成员和学会官员的列表。

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

介绍本期期刊的目录。

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

为有意提交稿件的作者提供说明和指南。

Advertisement: 2011 IEEE membership form.

广告：2011年IEEE会员表格。

This page or pages intentionally left blank.

此页或这些页故意留空。