Volume 29, Issue 3

We present the Spherical Demons algorithm for registering two spherical images. By exploiting spherical vector spline interpolation theory, we show that a large class of regularizors for the modified Demons objective function can be efficiently approximated on the sphere using iterative smoothing. Based on one parameter subgroups of diffeomorphisms, the resulting registration is diffeomorphic and fast. The Spherical Demons algorithm can also be modified to register a given spherical image to a probabilistic atlas. We demonstrate two variants of the algorithm corresponding to warping the atlas or warping the subject. Registration of a cortical surface mesh to an atlas mesh, both with more than 160 k nodes requires less than 5 min when warping the atlas and less than 3 min when warping the subject on a Xeon 3.2 GHz single processor machine. This is comparable to the fastest nondiffeomorphic landmark-free surface registration algorithms. Furthermore, the accuracy of our method compares favorably to the popular FreeSurfer registration algorithm. We validate the technique in two different applications that use registration to transfer segmentation labels onto a new image 1) parcellation of in vivo cortical surfaces and 2) Brodmann area localization in ex vivo cortical surfaces.

我们提出了用于配准两个球形图像的球形恶魔算法。通过利用球形向量样条插值理论，我们证明，通过迭代平滑可以在球面上有效逼近改进的恶魔目标函数的一大类正则化器。基于微分同胚的单参数子群，得到的配准是微分同胚且快速的。球形恶魔算法还可以修改为将给定的球面图像配准到概率图谱。我们展示了两种算法变体，对应于扭曲图谱或扭曲受试者。将皮质表面网格配准到图谱网格（两者都有超过16万个节点）在扭曲图谱时不到5分钟，在扭曲受试者时不到3分钟（在Xeon 3.2 GHz单处理器机器上）。这与最快的非微分同胚无标记表面配准算法相当。此外，我们的方法的准确性与流行的FreeSurfer配准算法相比具有优势。我们在两种不同的应用中验证了该技术，这些应用使用配准将分割标签转移到新图像：1）体内皮质表面的分割，以及2）离体皮质表面的布罗德曼区定位。

Cell segmentation and tracking in time-lapse fluorescence microscopy images is a task of fundamental importance in many biological studies on cell migration and proliferation. In recent years, level sets have been shown to provide a very appropriate framework for this purpose, as they are well suited to capture topological changes occurring during mitosis, and they easily extend to higher dimensio...

在时间序列荧光显微镜图像中进行细胞分割和追踪是许多关于细胞迁移和增殖的生物学研究中一项基本重要的任务。近年来，水平集已被证明为此目的提供了一个非常合适的框架，因为它们非常适合捕捉有丝分裂过程中发生的拓扑变化，并且易于扩展到更高维度...

Diffusion kurtosis imaging (DKI) is a new magnetic resonance imaging (MRI) model that describes the non-Gaussian diffusion behavior in tissues. It has recently been shown that DKI parameters, such as the radial or axial kurtosis, are more sensitive to brain physiology changes than the well-known diffusion tensor imaging (DTI) parameters in several white and gray matter structures. In order to esti...

扩散峰度成像（DKI）是一种新的磁共振成像（MRI）模型，描述组织中的非高斯扩散行为。最近研究表明，DKI参数（如径向或轴向峰度）在多个白质和灰质结构中比众所周知的扩散张量成像（DTI）参数对脑生理变化更敏感。为了估计...

Accurate system modeling in tomographic image reconstruction has been shown to reduce the spatial variance of resolution and improve quantitative accuracy. System modeling can be improved through analytic calculations, Monte Carlo simulations, and physical measurements. The purpose of this work is to improve clinical fully-3-D reconstruction without substantially increasing computation time. We pr...

断层图像重建中的精确系统建模已被证明可以减少空间分辨率方差并提高定量准确性。系统建模可以通过解析计算、蒙特卡罗模拟和物理测量来改进。本研究的目的在于不显著增加计算时间的情况下改善临床全三维重建。我们...

Motivated by the need for multimodal image registration in ophthalmology, this paper introduces an algorithm which is tailored to jointly align in a common reference space all the images in a complete fluorescein angiogram (FA) sequence, which contains both red-free (RF) and FA images. Our work is inspired by Generalized Dual-Bootstrap Iterative Closest Point (GDB-ICP), which rank-orders Lowe keyp...

受眼科多模态图像配准需求的驱动，本文介绍了一种算法，该算法专门用于将完整的荧光素血管造影（FA）序列中的所有图像（包括无红（RF）和FA图像）共同配准到同一参考空间。我们的工作受广义双自举迭代最近点（GDB-ICP）的启发，该算法对Lowe关键点进行排序...

Statistical models have shown considerable promise as a basis for segmenting and interpreting cardiac images. While a variety of statistical models have been proposed to improve the segmentation results, most of them are either static models (SMs), which neglect the temporal dynamics of a cardiac sequence, or generic dynamical models (GDMs), which are homogeneous in time and neglect the intersubje...

统计模型作为分割和解释心脏图像的基础已经显示出相当大的前景。虽然已经提出了各种统计模型来改善分割结果，但大多数模型要么是静态模型（SM），忽略了心脏序列的时间动态，要么是通用动态模型（GDM），在时间上是均匀的且忽略了个体间差异……

This paper proposes a novel algorithm to estimate a log-compressed K distribution parameter and presents an algorithm to discriminate breast tumors in ultrasonic images. We computed a total of 208 features for discrimination, including those based on a parameter of a log-compressed K-distribution, which quantifies the homogeneity of the echo pattern in the tumor, but is influenced by compression p...

本文提出了一种估计对数压缩K分布参数的新算法，并提出了一种在超声图像中鉴别乳腺肿瘤的算法。我们计算了总共208个鉴别特征，包括基于对数压缩K分布参数的特征，该参数量化了肿瘤内回声模式的均匀性，但受到压缩p的影响...

Electromechanical wave imaging (EWI) has recently been introduced as a noninvasive, ultrasound-based imaging modality, which could map the electrical activation of the heart in various echocardiographic planes in mice, dogs, and humans in vivo. By acquiring radio-frequency (RF) frames at very high frame rates (390–520 Hz), the onset of small, localized, transient deformations resulting from the el...

电机械波成像（EWI）最近被引入作为一种非侵入性的、基于超声的成像模态，能够在体内小鼠、狗和人类的各种超声心动图平面上绘制心脏的电活动。通过以非常高的帧率（390–520 Hz）采集射频（RF）帧，可以检测到由电激活引起的小的、局部的、瞬态变形的起始...

In this paper, we propose a coupled level set (LS) framework for segmentation of bladder wall using ${\rm T}_{1}$-weighted magnetic resonance (MR) images with clinical applications to virtual cystoscopy (i.e., MR cystography). The framework uses two collaborative LS functions and a regional adaptive clustering algorithm to delineate the bladder wall for the wall thickness measurement on a voxel-by...

本文提出了一种耦合水平集（LS）框架，用于T1加权磁共振（MR）图像中的膀胱壁分割，并应用于虚拟膀胱镜检查（即MR膀胱造影）。该框架使用两个协作的LS函数和区域自适应聚类算法，逐体素地描绘膀胱壁以测量壁厚...

Today's computer aided detection systems for computed tomography colonography (CTC) enable automated detection and segmentation of colorectal polyps. We present a paradigm shift by proposing a method that measures the amount of protrudedness of a candidate object in a scale adaptive fashion. One of the main results is that the performance of the candidate detection depends only on one parameter, t...

当今的计算机辅助检测系统能够实现CT结肠造影（CTC）中结直肠息肉的自动检测和分割。我们提出了一种范式转变，通过一种尺度自适应方式测量候选对象的突出程度。主要结果之一是候选检测的性能仅取决于一个参数……

Magnetic resonance poroelastography (MRPE) is introduced as an alternative to single-phase model-based elastographic reconstruction methods. A 3-D finite element poroelastic inversion algorithm was developed to recover the mechanical properties of fluid-saturated tissues. The performance of this algorithm was assessed through a variety of numerical experiments, using synthetic data to probe its st...

磁共振孔隙弹性成像（MRPE）被引入作为基于单相模型的弹性成像重建方法的替代方案。开发了一种三维有限元孔隙弹性反演算法，用于恢复流体饱和组织的力学特性。通过一系列数值实验，使用合成数据来评估该算法的性能...

A novel multiscale topomorphologic approach for opening of two isointensity objects fused at different locations and scales is presented and applied to separating arterial and venous trees in 3-D pulmonary multidetector X-ray computed tomography (CT) images. Initialized with seeds, the two isointensity objects (arteries and veins) grow iteratively while maintaining their spatial exclusiveness and ...

提出了一种新颖的多尺度拓扑形态学方法，用于在不同位置和尺度上打开两个融合的等强度对象，并将其应用于三维肺部多探测器X射线计算机断层扫描（CT）图像中动脉和静脉树的分离。以种子点初始化，两个等强度对象（动脉和静脉）迭代生长，同时保持空间排他性，并且...

High-resolution positron emission tomography (PET) scanners have brought many improvements to the nuclear medicine imaging field. However, the mechanical limitations in the construction of the scanners introduced gaps between the detectors, and accordingly, to the acquired projection data. When the methods requiring full-sinogram dataset, e.g., filtered backprojection (FBP) are applied, the missin...

高分辨率正电子发射断层扫描（PET）扫描仪为核医学成像领域带来了许多改进。然而，扫描仪制造中的机械限制导致探测器之间存在间隙，因此采集到的投影数据也存在间隙。当应用需要完整正弦图数据集的方法（例如滤波反投影（FBP））时，缺失...

X-ray computed tomography is a powerful medical imaging device. It allows high-resolution 3-D visualization of the human body. However, one drawback is the health risk associated with ionizing radiation. Simply downscaling the radiation intensities over the entire scan results in increased quantum noise. This paper proposes the concept of computer-assisted scan protocol and reconstruction. More sp...

X射线计算机断层扫描是一种强大的医学成像设备。它能够对人体进行高分辨率的三维可视化。然而，一个缺点是电离辐射带来的健康风险。简单地降低整个扫描的辐射强度会导致量子噪声增加。本文提出了计算机辅助扫描协议与重建的概念。更多...

This paper presents robust 3-D algorithms to segment vasculature that is imaged by labeling laminae, rather than the lumenal volume. The signal is weak, sparse, noisy, nonuniform, low-contrast, and exhibits gaps and spectral artifacts, so adaptive thresholding and Hessian filtering based methods are not effective. The structure deviates from a tubular geometry, so tracing algorithms are not effect...

本文提出了稳健的三维算法来分割通过标记层（而非管腔体积）成像的脉管系统。信号微弱、稀疏、有噪声、不均匀、对比度低，并存在间隙和光谱伪影，因此自适应阈值和基于Hessian滤波的方法效果不佳。该结构偏离管状几何，因此追踪算法无效。

For many image-guided interventions there exists a need to compute the registration between preprocedure image(s) and the physical space of the intervention. Real-time intraprocedure imaging such as ultrasound (US) can be used to image the region of interest directly and provide valuable anatomical information for computing this registration. Unfortunately, real-time US images often have poor sign...

对于许多影像引导的介入操作，需要计算术前影像与介入操作物理空间之间的配准。实时术中成像如超声（US）可以直接对感兴趣区域进行成像，并为计算此配准提供有价值的解剖信息。不幸的是，实时超声图像通常具有较差的信号...

The use of quantitative imaging for the characterization of hepatic tumors in magnetic resonance imaging (MRI) can improve the diagnosis and therefore the treatment of these life-threatening tumors. However, image parameters remain difficult to interpret because they result from a mixture of complex processes related to pathophysiology and to acquisition. These processes occur at variable spatial ...

在磁共振成像（MRI）中，使用定量成像表征肝脏肿瘤可以改善诊断，从而改善这些危及生命的肿瘤的治疗。然而，图像参数仍然难以解释，因为它们是由与病理生理学和采集相关的复杂过程的混合产生的。这些过程发生在不同的空间...

We study the effect of point dependent (heteroscedastic) and identically distributed anisotropic fiducial localization noise on fiducial target registration error (TRE). We derive an analytic expression, based on the concept of mechanism spatial stiffness, for predicting TRE. The accuracy of the predicted TRE is compared to simulated values where the optimal registration transformation is computed...

我们研究了点相关（异方差）和同分布各向异性基准定位噪声对基准目标配准误差（TRE）的影响。基于机制空间刚度的概念，我们推导了一个预测TRE的解析表达式。将预测TRE的精度与计算最优配准变换的模拟值进行比较...

A through description of the left ventricle functionality requires combining complementary regional scores. A main limitation is the lack of multiparametric normality models oriented to the assessment of regional wall motion abnormalities (RWMA). This paper covers two main topics involved in RWMA assessment. We propose a general framework allowing the fusion and comparison across subjects of diffe...

对左心室功能的全面描述需要结合互补的区域评分。一个主要限制是缺乏面向评估区域室壁运动异常（RWMA）的多参数正态模型。本文涵盖了RWMA评估所涉及的两个主要主题。我们提出了一个通用框架，允许在不同对象之间融合和比较微分...

Magnetic resonance (MR) cine images are often used to clinically assess left ventricular cardiac function. In a typical study, multiple 2-D long axis (LA) and short axis (SA) cine images are acquired, each in a different breath-hold. Differences in lung volume during breath-hold and overall patient motion distort spatial alignment of the images thus complicating spatial integration of all image da...

磁共振电影图像常用于临床评估左心室心脏功能。在典型研究中，获取多个二维长轴和短轴电影图像，每个图像在不同的屏气下采集。屏气期间肺容积差异和患者整体运动扭曲了图像的空间对齐，从而使所有图像数据的空间整合复杂化...

The evaluation of the quality of segmentations of an image, and the assessment of intra- and inter-expert variability in segmentation performance, has long been recognized as a difficult task. For a segmentation validation task, it may be effective to compare the results of an automatic segmentation algorithm to multiple expert segmentations. Recently an expectation-maximization (EM) algorithm for...

图像分割质量的评估，以及分割性能中专家内部和专家之间变异性的评估，长期以来被认为是一项困难的任务。对于分割验证任务，将自动分割算法的结果与多位专家分割结果进行比较可能是有效的。最近，一种用于...的期望最大化（EM）算法

The aim of this study is to interactively assess reendothelialization of stents at an accuracy of down to a few micrometer by analyzing endovascular optical coherence tomography (OCT) sequences. Vessel wall and stent struts are automatically detected by using morphological, gradient, and symmetry operators coupled with active contour models; alerts are issued to ask for user supervision over some ...

本研究旨在通过分析血管内光学相干断层扫描（OCT）序列，以高达几微米的精度交互式评估支架的再内皮化情况。利用形态学、梯度和对称算子结合主动轮廓模型自动检测血管壁和支架支柱；当检测需要用户监督时发出警报...

Computed radiography (CR) using storage phosphors is widely used in digital radiography and mammography. A cascaded linear systems approach wherein several parameter values were estimated using Monte Carlo methods was used to model the image formation process of a single-side read "flying spot" CR system using a granular phosphor. Objective image quality metrics such as modulation transfer functio...

使用存储磷光体的计算机放射摄影（CR）广泛应用于数字放射摄影和乳腺摄影。采用级联线性系统方法，其中若干参数值通过蒙特卡罗方法估计，用于模拟使用颗粒磷光体的单侧读取“飞点”CR系统的图像形成过程。诸如调制传递函数等客观图像质量指标...

Synthetic magnetic resonance (MR) imaging is an approach suggested in the literature to predict MR images at different design parameter settings from at least three observed MR scans. However, performance is poor when no regularization is used in the estimation and otherwise computationally impractical to implement for 3-D imaging methods. We propose a method which accounts for spatial context in ...

合成磁共振成像是一种在文献中提出的方法，旨在从至少三个观察到的MR扫描中预测不同设计参数设置下的MR图像。然而，当估计中不使用正则化时，性能很差，否则对于3D成像方法来说计算上不切实际。我们提出了一种考虑空间上下文的方法...

We study the 3-D imaging properties of a rotation-free micro-computed tomography (CT) system with square and hexagonal geometries. These systems use linear arrays of carbon-nanotube-based X-ray sources that are individually addressable. The source arrays and area detectors in the square and the hexagonal geometries form the sides of a polygon. The tomographic angular sampling for both geometries r...

我们研究了一种具有方形和六边形几何结构的无旋转微型计算机断层扫描(CT)系统的三维成像特性。这些系统使用基于碳纳米管的X射线源线性阵列，每个源可单独寻址。在方形和六边形几何结构中，源阵列和面探测器形成多边形的边。两种几何结构的断层角度采样...