Volume 34, Issue 2

The structure of microvasculature cannot be resolved using standard clinical ultrasound (US) imaging frequencies due to the fundamental diffraction limit of US waves. In this work, we use a standard clinical US system to perform in vivo sub-diffraction imaging on a CD1, female mouse aged eight weeks by localizing isolated US signals from microbubbles flowing within the ear microvasculature, and compare our results to optical microscopy. Furthermore, we develop a new technique to map blood velocity at super-resolution by tracking individual bubbles through the vasculature. Resolution is improved from a measured lateral and axial resolution of 112 μm and 94 μm respectively in original US data, to super-resolved images of microvasculature where vessel features as fine as 19 μm are clearly visualized. Velocity maps clearly distinguish opposing flow direction and separated speed distributions in adjacent vessels, thereby enabling further differentiation between vessels otherwise not spatially separated in the image. This technique overcomes the diffraction limit to provide a noninvasive means of imaging the microvasculature at super-resolution, to depths of many centimeters. In the future, this method could noninvasively image pathological or therapeutic changes in the microvasculature at centimeter depths in vivo.

由于超声波的固有衍射极限，标准临床超声成像频率无法解析微血管结构。在本工作中，我们使用标准临床超声系统，通过定位来自流经耳微血管的微泡的孤立超声信号，对一只八周龄的CD1雌性小鼠进行体内亚衍射成像，并将我们的结果与光学显微镜进行比较。此外，我们开发了一种新技术，通过追踪血管中的单个气泡来绘制超分辨血流速度。分辨率从原始超声数据中测量的横向112 μm和轴向94 μm提高到微血管超分辨图像，其中可清晰观察到细至19 μm的血管特征。速度图清晰区分相邻血管中的相反流动方向和分离的速度分布，从而进一步区分图像中原本未空间分离的血管。该技术突破了衍射极限，提供了一种非侵入性的超分辨微血管成像方法，深度可达数厘米。未来，该方法可无创地成像体内厘米深度处微血管的病理或治疗变化。

Automatic analysis of histopathological images has been widely utilized leveraging computational image-processing methods and modern machine learning techniques. Both computer-aided diagnosis (CAD) and content-based image-retrieval (CBIR) systems have been successfully developed for diagnosis, disease detection, and decision support in this area. Recently, with the ever-increasing amount of annota...

利用计算图像处理方法和现代机器学习技术，自动分析组织病理图像已被广泛应用。在该领域，计算机辅助诊断（CAD）和基于内容的图像检索（CBIR）系统已成功开发用于诊断、疾病检测和决策支持。近年来，随着注释数量的不断增加...

Automated retinal layer segmentation of optical coherence tomography (OCT) images has been successful for normal eyes but becomes challenging for eyes with retinal diseases if the retinal morphology experiences critical changes. We propose a method to automatically segment the retinal layers in 3-D OCT data with serous retinal pigment epithelial detachments (PED), which is a prominent feature of m...

光学相干断层扫描（OCT）图像的自动视网膜层分割在正常眼中已取得成功，但如果视网膜形态发生关键变化，对于患有视网膜疾病的眼则变得具有挑战性。我们提出一种方法，用于自动分割伴有浆液性视网膜色素上皮脱离（PED）的3D OCT数据中的视网膜层，这是...的一个显著特征。

Quantitative susceptibility mapping (QSM) is a magnetic resonance imaging technique that reveals tissue magnetic susceptibility. It relies on having a high quality field map, typically acquired with a relatively long echo spacing and long final TE. Applications of QSM outside the brain require the removal of fat contributions to the total signal phase. However, current water/fat separation methods...

定量磁化率成像（QSM）是一种揭示组织磁化率的磁共振成像技术。它依赖于高质量场图，通常通过相对较长的回波间隔和较长的最终TE获取。QSM在脑部以外的应用需要去除脂肪对总信号相位的贡献。然而，当前的水/脂肪分离方法...

We propose a new image recovery method to improve the resolution in microwave imaging applications. Scattered field data obtained from a simplified breast model with closely located targets is used to formulate an electromagnetic inverse scattering problem, which is then solved using the Distorted Born Iterative Method (DBIM). At each iteration of the DBIM method, an underdetermined set of linear ...

我们提出了一种新的图像恢复方法，以提高微波成像应用中的分辨率。使用从具有近距离目标的简化乳房模型获得的散射场数据来制定电磁逆散射问题，然后使用扭曲玻恩迭代法（DBIM）求解。在DBIM方法的每次迭代中，一组欠定线性...

This work reports the use of ultrasound radio frequency (RF) time series analysis as a method for ultrasound-based classification of malignant breast lesions. The RF time series method is versatile and requires only a few seconds of raw ultrasound data with no need for additional instrumentation. Using the RF time series features, and a machine learning framework, we have generated malignancy maps...

本工作报告了使用超声射频（RF）时间序列分析作为基于超声的恶性乳腺病变分类方法。RF时间序列方法用途广泛，仅需几秒钟的原始超声数据，无需额外仪器。利用RF时间序列特征和机器学习框架，我们生成了恶性图谱...

Raster-scan optoacoustic mesoscopy (RSOM) comes with high potential for in vivo diagnostic imaging in dermatology, since it allows for high resolution imaging of the natural chromophores melanin, and hemoglobin at depths of several millimeters. We have applied ultra-wideband RSOM, in the 10-160 MHz frequency band, to image healthy human skin at distinct locations. We analyzed the anatomical inform...

光栅扫描光声介观成像(RSOM)在皮肤科体内诊断成像方面具有很高的潜力，因为它能够在几毫米深度的高分辨率下对天然发色团黑色素和血红蛋白进行成像。我们应用了10-160 MHz频段的超宽带RSOM，对不同部位的健康人体皮肤进行了成像。我们分析了解剖学信息...

In this work, we present a novel algorithm for registration of 3-D volumetric ultrasound (US) and MR using Robust PaTch-based cOrrelation Ratio (RaPTOR). RaPTOR computes local correlation ratio (CR) values on small patches and adds the CR values to form a global cost function. It is therefore invariant to large amounts of spatial intensity inhomogeneity. We also propose a novel outlier suppression...

在本文中，我们提出了一种新颖的算法，用于使用基于鲁棒补丁的相关比（RaPTOR）对三维容积超声（US）和MR进行配准。RaPTOR计算小补丁上的局部相关比（CR）值，并将CR值相加形成全局成本函数。因此，它对大量的空间强度不均匀性具有不变性。我们还提出了一种新颖的异常值抑制方法...

It has been shown that magnetic particle imaging (MPI), an imaging method suggested in 2005, is capable of measuring the spatial distribution of magnetic nanoparticles. Since the particles can be administered as biocompatible suspensions, this method promises to perform well as a tracer-based medical imaging technique. It is capable of generating real-time images, which will be useful in intervent...

已有研究表明，2005年提出的磁粒子成像（MPI）方法能够测量磁性纳米颗粒的空间分布。由于这些颗粒可以以生物相容性悬浮液的形式给药，该方法有望作为一种基于示踪剂的医学成像技术表现出色。它能够生成实时图像，这将在介入治疗中发挥作用……

Tracking subcellular structures as well as viral structures displayed as `particles' in fluorescence microscopy images yields quantitative information on the underlying dynamical processes. We have developed an approach for tracking multiple fluorescent particles based on probabilistic data association. The approach combines a localization scheme that uses a bottom-up strategy based on the spot-en...

追踪荧光显微图像中显示为'粒子'的亚细胞结构以及病毒结构，可以获取关于潜在动态过程的定量信息。我们开发了一种基于概率数据关联的荧光粒子多目标追踪方法。该方法结合了一种定位方案，该方案采用基于点增强的自下而上策略...

Augmented Lagrangian (AL) methods for solving convex optimization problems with linear constraints are attractive for imaging applications with composite cost functions due to the empirical fast convergence rate under weak conditions. However, for problems such as X-ray computed tomography (CT) image reconstruction, where the inner least-squares problem is challenging and requires iterations, AL m...

增广拉格朗日(AL)方法用于求解带有线性约束的凸优化问题，由于在弱条件下具有经验快速收敛速度，对于具有复合代价函数的成像应用具有吸引力。然而，对于诸如X射线计算机断层扫描(CT)图像重建等问题，内部最小二乘问题具有挑战性且需要迭代，AL方法...

Statistical image reconstruction methods for X-ray computed tomography (CT) provide improved spatial resolution and noise properties over conventional filtered back-projection (FBP) reconstruction, along with other potential advantages such as reduced patient dose and artifacts. Conventional regularized image reconstruction leads to spatially variant spatial resolution and noise characteristics be...

X射线计算机断层扫描（CT）的统计图像重建方法在空间分辨率和噪声特性方面优于传统的滤波反投影（FBP）重建，同时还具有其他潜在优势，如降低患者剂量和伪影。传统的正则化图像重建会导致空间变异的空间分辨率和噪声特性...

This paper presents an approach to predict the deformation of the lungs and surrounding organs during respiration. The framework incorporates a computational model of the respiratory system, which comprises an anatomical model extracted from computed tomography (CT) images at end-expiration (EE), and a biomechanical model of the respiratory physiology, including the material behavior and interacti...

本文提出了一种预测呼吸过程中肺及周围器官变形的方法。该框架包含一个呼吸系统的计算模型，该模型由从呼气末CT图像中提取的解剖模型和呼吸生理的生物力学模型（包括材料行为及相互作用）组成。

Task-based assessments of image quality constitute a rigorous, principled approach to the evaluation of imaging system performance. To conduct such assessments, it has been recognized that mathematical model observers are very useful, particularly for purposes of imaging system development and optimization. One type of model observer that has been widely applied in the medical imaging community is...

基于任务的图像质量评估是对成像系统性能进行严格、有原则评估的一种方法。为了进行此类评估，人们认识到数学模型观察者非常有用，特别是在成像系统开发和优化方面。在医学影像界广泛使用的一种模型观察者是

The capability of magnetic resonance imaging (MRI) to produce spatially resolved estimation of tissue electrical properties (EPs) in vivo has been a subject of much recent interest. In this work we introduce a method to map tissue EPs from low-flip-angle, zero-echo-time (ZTE) imaging. It is based on a new theoretical formalism that allows calculation of EPs from the product of transmit and receive...

磁共振成像（MRI）在体内产生组织电特性（EPs）的空间分辨估计的能力最近引起了广泛关注。在这项工作中，我们介绍了一种从低翻转角、零回波时间（ZTE）成像中映射组织EPs的方法。它基于一种新的理论形式，允许从发射和接收的乘积计算EPs...

The interlocking of intramedullary nails is a technically demanding procedure which involves a considerable amount of X-ray acquisitions; one study lists as many as 48 to successfully complete the procedure and fix screws into 4-6 mm distal holes of the nail. We propose to design an augmented radiolucent drill to assist surgeons in completing the distal locking procedure without any additional X-r...

髓内钉的交锁是一项技术要求高的手术，需要进行大量的X射线采集；一项研究列出了多达48次X射线才能成功完成手术并将螺钉固定到钉子4-6毫米的远端孔中。我们提出设计一种增强型透光钻头，以帮助外科医生无需额外的X射线即可完成远端锁定手术。

Diastolic heart failure (DHF) is a major source of cardiac related morbidity and mortality in the world today. A major contributor to, or indicator of DHF is a change in cardiac compliance. Currently, there is no accepted clinical method to evaluate the compliance of cardiac tissue in diastolic dysfunction. Shear wave elasticity imaging (SWEI) is a novel ultrasound-based elastography technique tha...

舒张性心力衰竭（DHF）是全球心脏相关发病率和死亡率的主要原因。DHF的一个重要促成因素或指标是心脏顺应性的变化。目前，没有公认的临床方法来评估舒张功能障碍中心脏组织的顺应性。剪切波弹性成像（SWEI）是一种基于超声的新型弹性成像技术...

Laser Doppler flowmetry (LDF) and laser speckle contrast imaging (LSCI) have emerged as noninvasive optical modalities to monitor microvascular blood flow. Many studies proposed to extract physiological information from LDF by analyzing signals variability. By opposition, such analyses for LSCI data have not been conducted yet. We propose to analyze LSCI variability using a novel data-driven metho...

激光多普勒血流仪（LDF）和激光散斑对比成像（LSCI）已成为监测微血管血流的无创光学方式。许多研究提出通过分析信号变异性从LDF中提取生理信息。相比之下，对LSCI数据进行此类分析尚未进行。我们提出使用一种新的数据驱动方法分析LSCI变异性，并将结果与LDF信号变异性进行比较。

We hypothesize that quantification of structural similarity or dissimilarity between paired mammographic regions can be effective in detecting asymmetric signs of breast cancer. Bilateral masking procedures are applied for this purpose by using automatically detected anatomical landmarks. Changes in structural information of the extracted regions are investigated using spherical semivariogram desc...

我们假设，量化配对乳腺X线区域之间的结构相似性或差异性可以有效检测乳腺癌的不对称征象。为此，利用自动检测的解剖标志应用双侧掩膜程序。使用球形半变异函数描述研究提取区域结构信息的变化...

High-speed dual fluoroscopy is a noninvasive imaging technology for three-dimensional skeletal kinematics analysis that finds numerous biomechanical applications. Accurate reconstruction of bone translations and rotations from dual-fluoroscopic data requires accurate calibration of the imaging geometry and the many imaging distortions that corrupt the data. Direct linear transformation methods are...

高速双荧光成像是一种用于三维骨骼运动学分析的无创成像技术，具有众多生物力学应用。从双荧光数据中准确重建骨骼的平移和旋转需要对成像几何以及诸多影响数据的成像畸变进行精确校准。直接线性变换方法是...

Sparsity-promoting regularization is useful for combining compressed sensing assumptions with parallel MRI for reducing scan time while preserving image quality. Variable splitting algorithms are the current state-of-the-art algorithms for SENSE-type MR image reconstruction with sparsity-promoting regularization. These methods are very general and have been observed to work with almost any regular...

促进稀疏性的正则化对于将压缩感知假设与并行MRI相结合以减少扫描时间同时保持图像质量非常有用。变量分裂算法是目前用于具有稀疏性正则化的SENSE型MR图像重建的最先进算法。这些方法非常通用，并且已被观察到几乎适用于任何正则化...

Electrical conductivities of biological tissues show frequency-dependent behaviors, and these values at different frequencies may provide clinically useful diagnostic information. MR-based tissue property mapping techniques such as magnetic resonance electrical impedance tomography (MREIT) and magnetic resonance electrical property tomography (MREPT) are widely used and provide unique conductivity...

生物组织的电导率表现出频率依赖行为，不同频率下的电导率值可能提供临床有用的诊断信息。基于磁共振的组织特性映射技术，如磁共振电阻抗断层成像（MREIT）和磁共振电特性断层成像（MREPT），被广泛使用并提供独特的电导率信息。

Multi-pinhole collimators are often used in pre-clinical SPECT systems because they have a better resolution-sensitivity tradeoff than parallel hole collimators when imaging small objects. Most multi-pinhole collimators are designed to allow no or only a limited amount of overlap between the different pinhole projections because the ambiguity introduced by multiplexing pinholes can result in artif...

多针孔准直器常用于临床前SPECT系统，因为在对小物体成像时，它们比平行孔准直器具有更好的分辨率-灵敏度权衡。大多数多针孔准直器设计为不允许或仅允许不同针孔投影之间存在有限的重叠，因为复用针孔引入的模糊性可能导致伪影...

Three-dimensional (3-D) reconstruction of histological slice sequences offers great benefits in the investigation of different morphologies. It features very high-resolution which is still unmatched by in vivo 3-D imaging modalities, and tissue staining further enhances visibility and contrast. One important step during reconstruction is the reversal of slice deformations introduced during histolo...

组织学切片序列的三维重建在研究不同形态结构方面具有巨大优势。它具有非常高的分辨率，这在体内三维成像模态中仍然无可匹敌，组织染色进一步增强了可见性和对比度。重建过程中的一个重要步骤是逆转组织学过程中引入的切片变形...

When analyzing brain imaging data, blind source separation (BSS) techniques critically depend on the level of dimensional reduction. If the reduction level is too slight, the BSS model would be overfitted and become unavailable. Thus, the reduction level must be set relatively heavy. This approach risks discarding useful information and crucially limits the performance of BSS techniques. In this s...

在分析脑成像数据时，盲源分离技术关键依赖于降维程度。如果降维程度过小，BSS模型会过拟合而变得不可用。因此，降维程度必须设置得相对较重。这种方法有丢失有用信息的风险，并严重限制了BSS技术的性能。在这项研究中...