当小鼠脑中的解剖结构要注册为参考地图集时,小鼠脑显微镜图像的精确鉴定是至关重要的第一步。从业人员通常依赖于假定存在完整图像的图像或工具的手动比较。这项工作探索了暹罗网络,作为找到给定的部分2D小鼠脑图像的相应2D参考地图集板的方法。暹罗网络是一类卷积神经网络(CNN),它们使用重量共享路径来获得低维输入图像的低维嵌入。部分小鼠脑图像和参考地图集板之间的对应关系是基于使用对比度学习从暹罗网络获得的脑切片和地图集的低维嵌入之间的距离。实验表明,当训练和测试图像来自相同的来源时,暹罗CNN可以精确地使用艾伦小鼠脑图鉴定脑切片。他们分别获得了25%和100%的前1位和前5个精度,仅需7.2秒即可识别29张图像。
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对脑组织学数据分析的重大挑战是精确地识别解剖区域,以便进行准确的局部量化并评估治疗溶液。通常,这项任务是手动执行的,因此变得繁琐和主观。另一种选择是使用自动或半自动方法,其中使用数字atlase共同注册的分段。但是,最具可用的地图集是3D,而数字化的组织学数据是2D。需要从地图集执行此类2D-3D分段的方法。本文采用线性注册提出了一种在ATLA的3D体积内自动和准确地分割单个2D冠状切片的策略。我们使用全脑规模的探索方法验证了其鲁棒性和性能。
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可变形的图像注册对于许多医学图像分析是基础。准确图像注册的关键障碍在于图像外观变化,例如纹理,强度和噪声的变化。这些变化在医学图像中很明显,尤其是在经常使用注册的大脑图像中。最近,使用深神经网络的基于深度学习的注册方法(DLR)显示了计算效率,比基于传统优化的注册方法(ORS)快几个数量级。 DLR依靠一个全球优化的网络,该网络经过一组培训样本训练以实现更快的注册。但是,DLR倾向于无视ORS固有的目标对特异性优化,因此已经降低了对测试样品变化的适应性。这种限制对于注册出现较大的医学图像的限制是严重的,尤其是因为很少有现有的DLR明确考虑了外观的变化。在这项研究中,我们提出了一个外观调整网络(AAN),以增强DLR对外观变化的适应性。当我们集成到DLR中时,我们的AAN提供了外观转换,以减少注册过程中的外观变化。此外,我们提出了一个由解剖结构约束的损失函数,通过该函数,我们的AAN产生了解剖结构的转化。我们的AAN被目的设计为容易插入广泛的DLR中,并且可以以无监督和端到端的方式进行合作培训。我们用三个最先进的DLR评估了3D脑磁共振成像(MRI)的三个公共数据集(MRI)。结果表明,我们的AAN始终提高了现有的DLR,并且在注册精度上优于最先进的OR,同时向现有DLR增加了分数计算负载。
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We present VoxelMorph, a fast learning-based framework for deformable, pairwise medical image registration. Traditional registration methods optimize an objective function for each pair of images, which can be time-consuming for large datasets or rich deformation models. In contrast to this approach, and building on recent learning-based methods, we formulate registration as a function that maps an input image pair to a deformation field that aligns these images. We parameterize the function via a convolutional neural network (CNN), and optimize the parameters of the neural network on a set of images. Given a new pair of scans, VoxelMorph rapidly computes a deformation field by directly evaluating the function. In this work, we explore two different training strategies. In the first (unsupervised) setting, we train the model to maximize standard image matching objective functions that are based on the image intensities. In the second setting, we leverage auxiliary segmentations available in the training data. We demonstrate that the unsupervised model's accuracy is comparable to state-of-the-art methods, while operating orders of magnitude faster. We also show that VoxelMorph trained with auxiliary data improves registration accuracy at test time, and evaluate the effect of training set size on registration. Our method promises to speed up medical image analysis and processing pipelines, while facilitating novel directions in learning-based registration and its applications. Our code is freely available at http://voxelmorph.csail.mit.edu.
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基于模型的经颅超声疗法的治疗计划通常涉及从头部的X射线计算机断层扫描(CT)图像中映射头骨的声学特性。在这里,将三种用于从磁共振(MR)图像中生成伪CT图像的方法作为CT的替代方法。在配对的MR-CT图像上训练了卷积神经网络(U-NET),以从T1加权或零回波时间(ZTE)MR图像(分别表示TCT和ZCT)生成伪CT图像。还实施了从中兴通讯到伪CT的直接映射(表示为CCT)。在比较测试集的伪CT和地面真相CT图像时,整个头部的平均绝对误差为133、83和145 Hounsfield单位(HU),以及398、222和336 HU的头骨内的颅骨内部的平均误差为133、83和145个。 TCT,ZCT和CCT图像。还使用生成的伪CT图像进行了超声模拟,并将其与基于CT的模拟进行了比较。使用环形阵列传感器针对视觉或运动皮层。基于TCT图像的模拟,模拟局灶性局灶性,焦点位置和焦距的平均差异为9.9%,1.5 mm和15.1%,ZCT的平均差异为5.7%,0.6 mm和5.7%,为6.7%,和5.7% CCT为0.9毫米,为12.1%。映射的图像的改进结果突出了使用成像序列的优势,从而改善了颅骨的对比度。总体而言,这些结果表明,基于MR图像的声学仿真可以与基于CT的声学相比精度。
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面部变形攻击检测具有挑战性,并为面部验证系统带来了具体和严重的威胁。此类攻击的可靠检测机制已通过强大的跨数据库协议和未知的变形工具进行了测试,这仍然是一项研究挑战。本文提出了一个框架,遵循了几次射击学习方法,该方法使用三胞胎 - 硬性损坏共享基于暹罗网络的图像信息,以应对变形攻击检测并增强聚类分类过程。该网络比较了真正的或潜在的变形图像与变形和真正的面部图像的三胞胎。我们的结果表明,这个新的网络将数据点群集成,并将它们分配给类,以便在跨数据库方案中获得较低的相等错误率,仅共享来自未知数据库的小图像编号。几乎没有学习的学习有助于增强学习过程。使用FRGCV2训练并使用FERET和AMSL开放式数据库测试的跨数据库的实验结果将BPCer10使用RESNET50和5.50%的MobileNETV2从43%降低到4.91%。
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迄今为止,迄今为止,众所周知,对广泛的互补临床相关任务进行了全面比较了医学图像登记方法。这限制了采用研究进展,以防止竞争方法的公平基准。在过去五年内已经探讨了许多新的学习方法,但优化,建筑或度量战略的问题非常适合仍然是开放的。 Learn2reg涵盖了广泛的解剖学:脑,腹部和胸部,方式:超声波,CT,MRI,群体:患者内部和患者内部和监督水平。我们为3D注册的培训和验证建立了较低的入境障碍,这帮助我们从20多个独特的团队中汇编了65多个单独的方法提交的结果。我们的互补度量集,包括稳健性,准确性,合理性和速度,使得能够独特地位了解当前的医学图像登记现状。进一步分析监督问题的转移性,偏见和重要性,主要是基于深度学习的方法的优越性,并将新的研究方向开放到利用GPU加速的常规优化的混合方法。
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在几乎不可预测且通常严重的主题运动的情况下获得的多个MR Slices的胎儿大脑的体积重建是一项具有挑战性的任务,对切片转换的初始化非常敏感。我们建议使用经过合成转换数据训练的变压器提出了一种新型的切片到体积的注册方法,该数据将MR Slices的多个堆栈模拟为序列。通过注意机制,我们的模型会自动检测切片之间的相关性,并使用来自其他切片的信息预测一个切片的转换。我们还估计了基础3D卷,以帮助切片到体积的注册,并交替更新音量和转换以提高准确性。合成数据的结果表明,与现有的最新方法相比,我们的方法可实现较低的注册误差和更好的重建质量。还进行了使用现实世界中MRI数据的实验,以证明该模型在严重的胎儿运动下提高3D重建质量的能力。
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胎儿镜检查激光​​光凝是一种广泛采用的方法,用于治疗双胞胎输血综合征(TTTS)。该过程涉及光凝病理吻合术以调节双胞胎之间的血液交换。由于观点有限,胎儿镜的可操作性差,可见性差和照明的可变性,因此该程序尤其具有挑战性。这些挑战可能导致手术时间增加和消融不完全。计算机辅助干预措施(CAI)可以通过识别场景中的关键结构并通过视频马赛克来扩展胎儿镜观景领域,从而为外科医生提供决策支持和背景意识。由于缺乏设计,开发和测试CAI算法的高质量数据,该领域的研究受到了阻碍。通过作为MICCAI2021内窥镜视觉挑战组织的胎儿镜胎盘胎盘分割和注册(FETREG2021)挑战,我们发布了第一个Largescale Multencentre TTTS数据集,用于开发广义和可靠的语义分割和视频摩擦质量algorithms。对于这一挑战,我们发布了一个2060张图像的数据集,该数据集是从18个体内TTTS胎儿镜检查程序和18个简短视频剪辑的船只,工具,胎儿和背景类别的像素通道。七个团队参与了这一挑战,他们的模型性能在一个看不见的测试数据集中评估了658个从6个胎儿镜程序和6个短剪辑的图像的图像。这项挑战为创建通用解决方案提供了用于胎儿镜面场景的理解和摩西式解决方案的机会。在本文中,我们介绍了FETREG2021挑战的发现,以及报告TTTS胎儿镜检查中CAI的详细文献综述。通过这一挑战,它的分析和多中心胎儿镜数据的发布,我们为该领域的未来研究提供了基准。
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Purpose: This study aims to explore training strategies to improve convolutional neural network-based image-to-image registration for abdominal imaging. Methods: Different training strategies, loss functions, and transfer learning schemes were considered. Furthermore, an augmentation layer which generates artificial training image pairs on-the-fly was proposed, in addition to a loss layer that enables dynamic loss weighting. Results: Guiding registration using segmentations in the training step proved beneficial for deep-learning-based image registration. Finetuning the pretrained model from the brain MRI dataset to the abdominal CT dataset further improved performance on the latter application, removing the need for a large dataset to yield satisfactory performance. Dynamic loss weighting also marginally improved performance, all without impacting inference runtime. Conclusion: Using simple concepts, we improved the performance of a commonly used deep image registration architecture, VoxelMorph. In future work, our framework, DDMR, should be validated on different datasets to further assess its value.
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医疗图像注册和细分是多种临床程序的关键任务。这些任务的手动实现是耗时的,质量高度取决于医师的专业水平。为了减轻这项费力的任务,已经开发了自动工具,其中大多数解决方案都是有监督的技术。但是,在医疗领域中,拥有代表性的基础真理的强有力假设远非现实。为了克服这一挑战,已经研究了无监督的技术。但是,它们的性能仍然有限,并且无法产生合理的结果。在这项工作中,我们提出了一个新型的统一的无监督框架,用于图像注册和分割,我们称为PC-Swinmorph。我们框架的核心是两种基于补丁的策略,我们证明补丁表示是性能增益的关键。我们首先引入了基于补丁的对比策略,该策略可执行当地条件和更丰富的特征表示。其次,我们利用一个3D窗口/移动的窗口多头自发项模块作为补丁缝制策略,以消除贴片分裂中的人工制品。我们通过一组数值和视觉结果证明,我们的技术优于当前最新的无监督技术。
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Deep Metric Learning (DML) learns a non-linear semantic embedding from input data that brings similar pairs together while keeping dissimilar data away from each other. To this end, many different methods are proposed in the last decade with promising results in various applications. The success of a DML algorithm greatly depends on its loss function. However, no loss function is perfect, and it deals only with some aspects of an optimal similarity embedding. Besides, the generalizability of the DML on unseen categories during the test stage is an important matter that is not considered by existing loss functions. To address these challenges, we propose novel approaches to combine different losses built on top of a shared deep feature extractor. The proposed ensemble of losses enforces the deep model to extract features that are consistent with all losses. Since the selected losses are diverse and each emphasizes different aspects of an optimal semantic embedding, our effective combining methods yield a considerable improvement over any individual loss and generalize well on unseen categories. Here, there is no limitation in choosing loss functions, and our methods can work with any set of existing ones. Besides, they can optimize each loss function as well as its weight in an end-to-end paradigm with no need to adjust any hyper-parameter. We evaluate our methods on some popular datasets from the machine vision domain in conventional Zero-Shot-Learning (ZSL) settings. The results are very encouraging and show that our methods outperform all baseline losses by a large margin in all datasets.
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从磁共振成像(MRI)数据(称为颅骨条状)中去除非脑信号是许多神经图像分析流的组成部分。尽管它们很丰富,但通常是针对具有特定采集特性的图像量身定制的,即近乎各向异性的分辨率和T1加权(T1W)MRI对比度,这些分辨率在研究环境中很普遍。结果,现有的工具倾向于适应其他图像类型,例如在诊所常见的快速旋转回声(FSE)MRI中获得的厚切片。尽管近年来基于学习的大脑提取方法已获得吸引力,但这些方法面临着类似的负担,因为它们仅对训练过程中看到的图像类型有效。为了在成像协议的景观中实现强大的颅骨缠身,我们引入了Synthstrip,这是一种快速,基于学习的脑萃取工具。通过利用解剖学分割来生成具有解剖学,强度分布和远远超过现实医学图像范围的完全合成训练数据集,Synthstrip学会了成功推广到各种真实获得的大脑图像,从而消除了使用训练数据的需求目标对比。我们证明了合成条的功效对受试者人群的各种图像采集和决议的功效,从新生儿到成人。我们显示出与流行的颅骨基线的准确性的实质性提高 - 所有这些基线都采用单个训练有素的模型。我们的方法和标记的评估数据可在https://w3id.org/synthstrip上获得。
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Jitendra Malik once said, "Supervision is the opium of the AI researcher". Most deep learning techniques heavily rely on extreme amounts of human labels to work effectively. In today's world, the rate of data creation greatly surpasses the rate of data annotation. Full reliance on human annotations is just a temporary means to solve current closed problems in AI. In reality, only a tiny fraction of data is annotated. Annotation Efficient Learning (AEL) is a study of algorithms to train models effectively with fewer annotations. To thrive in AEL environments, we need deep learning techniques that rely less on manual annotations (e.g., image, bounding-box, and per-pixel labels), but learn useful information from unlabeled data. In this thesis, we explore five different techniques for handling AEL.
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在过去的十年中,卷积神经网络(Convnets)主导了医学图像分析领域。然而,发现脉搏的性能仍然可以受到它们无法模拟图像中体素之间的远程空间关系的限制。最近提出了众多视力变压器来解决哀悼缺点,在许多医学成像应用中展示最先进的表演。变压器可以是用于图像配准的强烈候选者,因为它们的自我注意机制能够更精确地理解移动和固定图像之间的空间对应。在本文中,我们呈现透射帧,一个用于体积医学图像配准的混合变压器-Cromnet模型。我们还介绍了三种变速器的变形,具有两个散晶变体,确保了拓扑保存的变形和产生良好校准的登记不确定性估计的贝叶斯变体。使用来自两个应用的体积医学图像的各种现有的登记方法和变压器架构进行广泛验证所提出的模型:患者间脑MRI注册和幻影到CT注册。定性和定量结果表明,传输和其变体导致基线方法的实质性改进,展示了用于医学图像配准的变压器的有效性。
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Brain extraction and registration are important preprocessing steps in neuroimaging data analysis, where the goal is to extract the brain regions from MRI scans (i.e., extraction step) and align them with a target brain image (i.e., registration step). Conventional research mainly focuses on developing methods for the extraction and registration tasks separately under supervised settings. The performance of these methods highly depends on the amount of training samples and visual inspections performed by experts for error correction. However, in many medical studies, collecting voxel-level labels and conducting manual quality control in high-dimensional neuroimages (e.g., 3D MRI) are very expensive and time-consuming. Moreover, brain extraction and registration are highly related tasks in neuroimaging data and should be solved collectively. In this paper, we study the problem of unsupervised collective extraction and registration in neuroimaging data. We propose a unified end-to-end framework, called ERNet (Extraction-Registration Network), to jointly optimize the extraction and registration tasks, allowing feedback between them. Specifically, we use a pair of multi-stage extraction and registration modules to learn the extraction mask and transformation, where the extraction network improves the extraction accuracy incrementally and the registration network successively warps the extracted image until it is well-aligned with the target image. Experiment results on real-world datasets show that our proposed method can effectively improve the performance on extraction and registration tasks in neuroimaging data. Our code and data can be found at https://github.com/ERNetERNet/ERNet
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Deep embeddings answer one simple question: How similar are two images? Learning these embeddings is the bedrock of verification, zero-shot learning, and visual search. The most prominent approaches optimize a deep convolutional network with a suitable loss function, such as contrastive loss or triplet loss. While a rich line of work focuses solely on the loss functions, we show in this paper that selecting training examples plays an equally important role. We propose distance weighted sampling, which selects more informative and stable examples than traditional approaches. In addition, we show that a simple margin based loss is sufficient to outperform all other loss functions. We evaluate our approach on the Stanford Online Products, CAR196, and the CUB200-2011 datasets for image retrieval and clustering, and on the LFW dataset for face verification. Our method achieves state-of-the-art performance on all of them.
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医学计算机视觉的最新自我监督进步利用了在下游任务(例如分割)之前预处理的全球和局部解剖自我相似性。但是,当前方法假设I.I.D.图像采集是在临床研究设计中无效的,其中随访纵向扫描跟踪特定于主体的时间变化。此外,现有的自我监督方法用于医学上相关的图像到图像体系结构仅利用空间或时间自相似性,并且仅通过在单个图像尺度上应用的损失来进行,而天真的多尺度空间时空扩展崩溃了解决方案。对于这些目的,本文做出了两种贡献:(1)它提出了一种局部和多规模的时空表示方法,用于对纵向图像进行训练的图像到图像架构。它利用了学到的多尺度内部主体内特征的时空自相似性来进行训练,并开发出几种特征正规化,以避免崩溃的身份表示。 (2)在填充期间,它提出了一个令人惊讶的简单的自我监督分割一致性正规化以利用受试者内部的相关性。该框架以单次分割设置为基准,该框架的表现优于良好调整的随机定位基线和为I.I.D设计的当前自我监督技术。和纵向数据集。在纵向神经退行性的成年MRI和发育的婴儿脑MRI中,这些改进都得到了证明,并产生了更高的性能和纵向一致性。
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必须在密集的注释图像上培训最先进的实例分段方法。虽然一般而言,这一要求对于生物医学图像尤其令人生畏,其中域专业知识通常需要注释,没有大的公共数据收集可用于预培训。我们建议通过基于非空间嵌入的非空间嵌入的联盟分割方法来解决密集的注释瓶颈,该方法利用所学习的嵌入空间的结构以可分散的方式提取单个实例。然后可以将分割损耗直接应用于实例,整体管道可以以完全或弱监督的方式培训,包括积极解贴的监管的具有挑战性的情况,其中为未标记的部分引入了一种新的自我监督的一致性损失训练数据。我们在不同显微镜模型以及城市景观和CVPPP实例分段基准中评估了对2D和3D分段问题的提出的方法,在后者上实现最先进的结果。该代码可用于:https://github.com/kreshuklab/spoco
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Deformable image registration, i.e., the task of aligning multiple images into one coordinate system by non-linear transformation, serves as an essential preprocessing step for neuroimaging data. Recent research on deformable image registration is mainly focused on improving the registration accuracy using multi-stage alignment methods, where the source image is repeatedly deformed in stages by a same neural network until it is well-aligned with the target image. Conventional methods for multi-stage registration can often blur the source image as the pixel/voxel values are repeatedly interpolated from the image generated by the previous stage. However, maintaining image quality such as sharpness during image registration is crucial to medical data analysis. In this paper, we study the problem of anti-blur deformable image registration and propose a novel solution, called Anti-Blur Network (ABN), for multi-stage image registration. Specifically, we use a pair of short-term registration and long-term memory networks to learn the nonlinear deformations at each stage, where the short-term registration network learns how to improve the registration accuracy incrementally and the long-term memory network combines all the previous deformations to allow an interpolation to perform on the raw image directly and preserve image sharpness. Extensive experiments on both natural and medical image datasets demonstrated that ABN can accurately register images while preserving their sharpness. Our code and data can be found at https://github.com/anonymous3214/ABN
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