在临床程序期间的医学成像中的机器学习因扫描仪协议,硬件或政策的变化而受到损害,从而产生异构的采集设置。当训练初始静态训练集的深度学习模型时,模型性能和可靠性遭受采集特征的变化,因为数据和目标可能变得不一致。持续学习可以通过在连续数据流上培训来帮助将模型适应变化环境。然而,医学成像的持续手动专家标签需要大量努力。因此,有效地在新的新示例上有效地使用标签资源的方法是使这一策略可行的必要的。这里,我们提出了一种在多扫描仪设置中在医学图像流上运行的持续主动学习的方法。该方法自动识别图像采集特性中的变化 - 新域 - 选择标签和相应地适应培训的最佳示例。标签受限预算有限,类似典型的真实世界情景。为了证明概括性,我们评估了我们三项任务的方法的有效性:心脏分割,肺结核检测和脑年龄估计。结果表明,建议的方法优于其他主动学习方法,同时有效地抵消灾难性的遗忘。
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休息状态功能磁共振成像(FMRI)是一种强大的成像技术,用于研究UTETO脑功能的功能发展。然而,胎儿的不可预测和过度运动具有有限的临床应用,因为它导致可以系统地改变了功能连接模式的大量信号波动。以前的研究专注于在大胎儿头部运动的情况下的运动参数的准确估计,并在每个时间点使用3D单步插值方法来恢复无动态的FMRI图像。这并不保证重建的图像对应于给定获取的数据的FMRI时间序列的最小错误表示。在这里,我们提出了一种基于胎儿FMRI散射切片的四维迭代重建的新技术。在一组真正的临床FMRI胎儿上定量评估所提出的方法的准确性。结果表明与传统的3D插值方法相比,重建质量的改进。
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在多中心随机临床试验中,由于采集技术或扫描协议,可以多样化成像数据。预测未来患者未来结果的模型受此数据异质性受到损害。在这里,我们提出了一种预测方法,其可以应对大量不同的扫描位点和每位站点的少量样本。根据扫描的视觉外观,我们将网站群集到伪域,并列车伪域特定模型。结果表明,在初步访问中获得的成像数据和肝脏疾病中12周随访的成像数据后,它们在48周后提高了脂肪变性的预测准确性
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限制机器学习系统的故障对于安全至关重要的应用至关重要。为了提高机器学习系统的鲁棒性,已提出了分配鲁棒优化(DRO)作为经验风险最小化(ERM)的概括。然而,由于与ERM的随机梯度下降(SGD)优化器相比,由于可用于DRO的优化器的相对效率相对效率相对低效率,因此在深度学习中的使用受到了严格的限制。我们建议使用硬度加权采样的SGD,这是机器学习中DRO的原则性高效优化方法,在深度学习的背景下特别适合。与实践中的硬示例挖掘策略类似,所提出的算法可以直接实施和计算,并且与用于深度学习的基于SGD的优化器一样有效,需要最小的开销计算。与典型的临时硬采矿方法相反,我们证明了我们的DRO算法的收敛性,用于过度参数化的深度学习网络,并具有RELU激活以及有限数量的层和参数。我们对MRI中胎儿脑3D MRI分割和脑肿瘤分割的实验证明了我们方法的可行性和有用性。使用我们的硬度加权采样进行训练,最先进的深度学习管道可改善自动胎儿脑中解剖学变异的鲁棒性3D MRI分割,并改善了对脑肿瘤分割的图像方案变化的鲁棒性。我们的代码可从https://github.com/lucasfidon/hardnessweightedsampler获得。
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Obtaining models that capture imaging markers relevant for disease progression and treatment monitoring is challenging. Models are typically based on large amounts of data with annotated examples of known markers aiming at automating detection. High annotation effort and the limitation to a vocabulary of known markers limit the power of such approaches. Here, we perform unsupervised learning to identify anomalies in imaging data as candidates for markers. We propose AnoGAN, a deep convolutional generative adversarial network to learn a manifold of normal anatomical variability, accompanying a novel anomaly scoring scheme based on the mapping from image space to a latent space. Applied to new data, the model labels anomalies, and scores image patches indicating their fit into the learned distribution. Results on optical coherence tomography images of the retina demonstrate that the approach correctly identifies anomalous images, such as images containing retinal fluid or hyperreflective foci.
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In this paper, we present a modular methodology that combines state-of-the-art methods in (stochastic) machine learning with traditional methods in rule learning to provide efficient and scalable algorithms for the classification of vast data sets, while remaining explainable. Apart from evaluating our approach on the common large scale data sets MNIST, Fashion-MNIST and IMDB, we present novel results on explainable classifications of dental bills. The latter case study stems from an industrial collaboration with Allianz Private Krankenversicherungs-Aktiengesellschaft which is an insurance company offering diverse services in Germany.
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Key Point Analysis(KPA) is a relatively new task in NLP that combines summarization and classification by extracting argumentative key points (KPs) for a topic from a collection of texts and categorizing their closeness to the different arguments. In our work, we focus on the legal domain and develop methods that identify and extract KPs from premises derived from texts of judgments. The first method is an adaptation to an existing state-of-the-art method, and the two others are new methods that we developed from scratch. We present our methods and examples of their outputs, as well a comparison between them. The full evaluation of our results is done in the matching task -- match between the generated KPs to arguments (premises).
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We show how the inherent, but often neglected, properties of large-scale LiDAR point clouds can be exploited for effective self-supervised representation learning. To this end, we design a highly data-efficient feature pre-training backbone that significantly reduces the amount of tedious 3D annotations to train state-of-the-art object detectors. In particular, we propose a Masked AutoEncoder (MAELi) that intuitively utilizes the sparsity of the LiDAR point clouds in both, the encoder and the decoder, during reconstruction. This results in more expressive and useful features, directly applicable to downstream perception tasks, such as 3D object detection for autonomous driving. In a novel reconstruction scheme, MAELi distinguishes between free and occluded space and leverages a new masking strategy which targets the LiDAR's inherent spherical projection. To demonstrate the potential of MAELi, we pre-train one of the most widespread 3D backbones, in an end-to-end fashion and show the merit of our fully unsupervised pre-trained features on several 3D object detection architectures. Given only a tiny fraction of labeled frames to fine-tune such detectors, we achieve significant performance improvements. For example, with only $\sim800$ labeled frames, MAELi features improve a SECOND model by +10.09APH/LEVEL 2 on Waymo Vehicles.
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Research connecting text and images has recently seen several breakthroughs, with models like CLIP, DALL-E 2, and Stable Diffusion. However, the connection between text and other visual modalities, such as lidar data, has received less attention, prohibited by the lack of text-lidar datasets. In this work, we propose LidarCLIP, a mapping from automotive point clouds to a pre-existing CLIP embedding space. Using image-lidar pairs, we supervise a point cloud encoder with the image CLIP embeddings, effectively relating text and lidar data with the image domain as an intermediary. We show the effectiveness of LidarCLIP by demonstrating that lidar-based retrieval is generally on par with image-based retrieval, but with complementary strengths and weaknesses. By combining image and lidar features, we improve upon both single-modality methods and enable a targeted search for challenging detection scenarios under adverse sensor conditions. We also use LidarCLIP as a tool to investigate fundamental lidar capabilities through natural language. Finally, we leverage our compatibility with CLIP to explore a range of applications, such as point cloud captioning and lidar-to-image generation, without any additional training. We hope LidarCLIP can inspire future work to dive deeper into connections between text and point cloud understanding. Code and trained models available at https://github.com/atonderski/lidarclip.
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The quality of consequences in a decision making problem under (severe) uncertainty must often be compared among different targets (goals, objectives) simultaneously. In addition, the evaluations of a consequence's performance under the various targets often differ in their scale of measurement, classically being either purely ordinal or perfectly cardinal. In this paper, we transfer recent developments from abstract decision theory with incomplete preferential and probabilistic information to this multi-target setting and show how -- by exploiting the (potentially) partial cardinal and partial probabilistic information -- more informative orders for comparing decisions can be given than the Pareto order. We discuss some interesting properties of the proposed orders between decision options and show how they can be concretely computed by linear optimization. We conclude the paper by demonstrating our framework in an artificial (but quite real-world) example in the context of comparing algorithms under different performance measures.
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