Volume 26, Issue 1

In dynamic magnetic resonance imaging (MRI) studies, the motion kinetics or the contrast variability are often hard to predict, hampering an appropriate choice of the image update rate or the temporal resolution. A constant azimuthal profile spacing (111.246deg), based on the Golden Ratio, is investigated as optimal for image reconstruction from an arbitrary number of profiles in radial MRI. The profile order is evaluated and compared with a uniform profile distribution in terms of signal-to-noise ratio (SNR) and artifact level. The favorable characteristics of such a profile order are exemplified in two applications on healthy volunteers. First, an advanced sliding window reconstruction scheme is applied to dynamic cardiac imaging, with a reconstruction window that can be flexibly adjusted according to the extent of cardiac motion that is acceptable. Second, a contrast-enhancing k-space filter is presented that permits reconstructing an arbitrary number of images at arbitrary time points from one raw data set. The filter was utilized to depict the T1-relaxation in the brain after a single inversion prepulse. While a uniform profile distribution with a constant angle increment is optimal for a fixed and predetermined number of profiles, a profile distribution based on the Golden Ratio proved to be an appropriate solution for an arbitrary number of profiles

在动态磁共振成像（MRI）研究中，运动动力学或对比度变化往往难以预测，阻碍了对图像更新速率或时间分辨率的适当选择。基于黄金比例的恒定方位角轮廓间距（111.246°）被研究为径向MRI中从任意数量轮廓进行图像重建的最优方案。该轮廓顺序在信噪比（SNR）和伪影水平方面与均匀轮廓分布进行了评估和比较。该轮廓顺序的有利特性在两个健康志愿者的应用中得到了例证。首先，一种先进的滑动窗口重建方案应用于动态心脏成像，重建窗口可根据可接受的心脏运动程度灵活调整。其次，提出了一种对比度增强的k空间滤波器，允许从单个原始数据集在任意时间点重建任意数量的图像。该滤波器用于描绘单次反转预脉冲后大脑中的T1弛豫。虽然固定和预定轮廓数的均匀轮廓分布（恒定角度增量）是最优的，但基于黄金比例的轮廓分布被证明是任意数量轮廓的合适解决方案。

This paper presents a method for classification of structural brain magnetic resonance (MR) images, by using a combination of deformation-based morphometry and machine learning methods. A morphological representation of the anatomy of interest is first obtained using a high-dimensional mass-preserving template warping method, which results in tissue density maps that constitute local tissue volume...

本文提出了一种结合变形形态测量学和机器学习方法的结构性脑磁共振图像分类方法。首先使用高维质量保持模板扭曲方法获得感兴趣解剖结构的形态表示，从而产生构成局部组织体积的组织密度图...

Displacement encoding with stimulated echoes (DENSE) encodes myocardial tissue displacement into the phase of the MR image. Cine DENSE allows for rapid quantification of myocardial displacement at multiple cardiac phases through the majority of the cardiac cycle. For practical sensitivities to motion, relatively high displacement encoding frequencies are used and phase wrapping typically occurs. I...

位移编码刺激回波（DENSE）将心肌组织位移编码到MR图像的相位中。电影DENSE允许在大多数心动周期内以多个心相位快速量化心肌位移。为了对运动具有实际灵敏度，使用相对较高的位移编码频率，通常会发生相位包裹。本...

An automatic system is presented to find the location of the major anatomical structures in color fundus photographs; the optic disc, the macula, and the vascular arch. These structures are found by fitting a single point-distribution-model to the image, that contains points on each structure. The method can handle optic disc and macula centered images of both the left and the right eye. The syste...

提出了一种自动系统，用于在彩色眼底照片中定位主要解剖结构的位置：视盘、黄斑和血管弓。这些结构通过将包含每个结构点的单一分布模型拟合到图像中来找到。该方法可以处理左眼和右眼的视盘和黄斑中心图像。系...

We present a fully automatic method for articular cartilage segmentation from magnetic resonance imaging (MRI) which we use as the foundation of a quantitative cartilage assessment. We evaluate our method by comparisons to manual segmentations by a radiologist and by examining the interscan reproducibility of the volume and area estimates. Training and evaluation of the method is performed on a da...

我们提出了一种全自动方法，用于从磁共振成像（MRI）中分割关节软骨，并将其作为定量软骨评估的基础。我们通过与放射科医师的手动分割进行比较，并检查体积和面积估计的扫描间重复性来评估我们的方法。该方法的训练和评估在...上进行。

Interest in the morphometric analysis of the brain and its subregions has recently intensified because growth or degeneration of the brain in health or illness affects not only the volume but also the shape of cortical and subcortical brain regions, and new image processing techniques permit detection of small and highly localized perturbations in shape or localized volume, with remarkable precisi...

近年来，对大脑及其亚区域的形态计量分析引起了越来越多的关注，因为健康或疾病状态下大脑的生长或退化不仅影响体积，还影响皮质和皮质下脑区域的形状，而新的图像处理技术能够以前所未有的精度检测形状或局部体积的微小且高度局部的扰动。

The blood in the carotid arteries exhibits time-varying flow velocity as a function of cardiac phases. Despite this flow velocity variation, most current methods set forth for the analysis of arterial spin labeling (ASL) data have assumed that the tagged blood is delivered from the tagging region to the imaging region via simple plug flow, i.e., a single transit delay (deltat). In this study, we u...

颈动脉中的血液表现出随心脏相位变化的时间流速。尽管存在这种流速变化，目前大多数用于分析动脉自旋标记（ASL）数据的方法都假设标记血液通过简单的活塞流从标记区域输送到成像区域，即单一传输延迟（ΔT）。在这项研究中，我们...

We present a new computational method for reconstructing a vector velocity field from scattered, pulsed-wave ultrasound Doppler data. The main difficulty is that the Doppler measurements are incomplete, for they do only capture the velocity component along the beam direction. We thus propose to combine measurements from different beam directions. However, this is not yet sufficient to make the pro...

我们提出了一种新的计算方法，用于从分散的脉冲波超声多普勒数据重建矢量速度场。主要困难在于多普勒测量是不完整的，因为它们只捕获沿波束方向的速度分量。因此，我们建议结合来自不同波束方向的测量。然而，这还不足以使问题完全确定……

Recently, foundations rooted in physics have been laid down for the goal of simulating the propagation of a guide wire inside the vasculature. At the heart of the simulation lies the fundamental task of energy minimization. The energy comes from interaction with the vessel wall and the bending of the guide wire. For the simulation to be useful in actual training, obtaining the smallest possible op...

最近，为了模拟导丝在血管内的传播这一目标，已经奠定了基于物理学的基础。模拟的核心是能量最小化这一基本任务。能量来自与血管壁的相互作用以及导丝的弯曲。为了使模拟在实际训练中有用，需要获得尽可能小的操作...

We describe a fast and globally convergent fully four-dimensional incremental gradient (4DIG) algorithm to estimate the continuous-time tracer density from list mode positron emission tomography (PET) data. Detection of 511-keV photon pairs produced by positron-electron annihilation is modeled as an inhomogeneous Poisson process whose rate function is parameterized using cubic $B$-splines. The ra...

我们描述了一种快速且全局收敛的全四维增量梯度（4DIG）算法，用于从列表模式正电子发射断层扫描（PET）数据中估计连续时间示踪剂密度。将正电子-电子湮灭产生的511 keV光子对检测建模为非齐次泊松过程，其速率函数使用三次B样条参数化。

In this paper, a multiresolution volumetric texture segmentation (M-VTS) algorithm is presented. The method extracts textural measurements from the Fourier domain of the data via subband filtering using an orientation pyramid (Wilson and Spann, 1988). A novel Bhattacharyya space, based on the Bhattacharyya distance, is proposed for selecting the most discriminant measurements and producing a compa...

本文提出了一种多分辨率体积纹理分割算法。该方法通过使用方向金字塔进行子带滤波，从数据的傅里叶域提取纹理测量。提出了一种基于Bhattacharyya距离的新型Bhattacharyya空间，用于选择最具判别力的测量并生成压缩...

Many attempts have been made to develop an optimal linear observer for classifying multiclass data. Most approaches either do not have a definite description of optimality or have regions of ambiguity in decision making. In this paper, we derive a three-class Hotelling observer (3-HO), inspired by the ideal observer that results from a decision theoretic solution to the three-class classification ...

人们已经尝试了许多方法来开发用于多类数据分类的最优线性观察者。大多数方法要么没有明确的优化描述，要么在决策中存在模糊区域。在本文中，我们推导出了一种三分类Hotelling观察者（3-HO），其灵感来自于由决策理论解得到的三分类问题中的理想观察者。

In order to detect vessels at a variety of widths, we apply the matched filter at multiple scales (i.e., compute for multiple values and then combine the responses across scales). Unfortunately, the output amplitudes of spatial operators such as derivatives or matched filters generally decrease with increasing scale. To compensate for this effect, Lindeberg introduced gamma-normalized derivatives....

为了检测不同宽度的血管，我们在多个尺度上应用匹配滤波器（即，计算多个值，然后结合跨尺度的响应）。不幸的是，导数或匹配滤波器等空间算子的输出幅度通常随着尺度的增加而减小。为了补偿这种效应，Lindeberg引入了伽马归一化导数……

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