域移位，训练与测试数据特征之间的不匹配，导致多源成像方案中的预测性能显着降低。在医学成像中，不同网站的人口，扫描仪和采集协议的异质性提出了一个重要的领域移位挑战，并限制了机器学习模型的广泛临床采用。统一方法旨在学习数据不变的表示这些差异是解决域移位的普遍工具，但它们通常会导致预测精度的劣化。本文对问题进行了不同的视角：我们拥抱这种不和谐的数据并设计一个简单但有效的解决域名框架。根据我们的理论参数，关键的想法是在源数据上构建备用分类器并将此模型调整为新数据。可以为站点内域适应微调分类器。我们还可以在目标数据上处理我们无法访问地面真理标签的情况;我们展示如何使用辅助任务来适应;这些任务雇用协变量，如年龄，性别和种族，这很容易获得，但仍然与主要任务相关联。我们在大规模现实世界3D脑MRI数据集上展示了站点内部域适应和站点间域推广的大量改进，用于分类阿尔茨海默病和精神分裂症。

Late-life depression (LLD) is a highly prevalent mood disorder occurring in older adults and is frequently accompanied by cognitive impairment (CI). Studies have shown that LLD may increase the risk of Alzheimer's disease (AD). However, the heterogeneity of presentation of geriatric depression suggests that multiple biological mechanisms may underlie it. Current biological research on LLD progression incorporates machine learning that combines neuroimaging data with clinical observations. There are few studies on incident cognitive diagnostic outcomes in LLD based on structural MRI (sMRI). In this paper, we describe the development of a hybrid representation learning (HRL) framework for predicting cognitive diagnosis over 5 years based on T1-weighted sMRI data. Specifically, we first extract prediction-oriented MRI features via a deep neural network, and then integrate them with handcrafted MRI features via a Transformer encoder for cognitive diagnosis prediction. Two tasks are investigated in this work, including (1) identifying cognitively normal subjects with LLD and never-depressed older healthy subjects, and (2) identifying LLD subjects who developed CI (or even AD) and those who stayed cognitively normal over five years. To the best of our knowledge, this is among the first attempts to study the complex heterogeneous progression of LLD based on task-oriented and handcrafted MRI features. We validate the proposed HRL on 294 subjects with T1-weighted MRIs from two clinically harmonized studies. Experimental results suggest that the HRL outperforms several classical machine learning and state-of-the-art deep learning methods in LLD identification and prediction tasks.

生成的对抗网络（GAN）是在众多领域成功使用的一种强大的深度学习模型。它们属于一个称为生成方法的更广泛的家族，该家族通过从真实示例中学习样本分布来生成新数据。在临床背景下，与传统的生成方法相比，GAN在捕获空间复杂，非线性和潜在微妙的疾病作用方面表现出增强的能力。这篇综述评估了有关gan在各种神经系统疾病的成像研究中的应用的现有文献，包括阿尔茨海默氏病，脑肿瘤，脑老化和多发性硬化症。我们为每个应用程序提供了各种GAN方法的直观解释，并进一步讨论了在神经影像学中利用gans的主要挑战，开放问题以及有希望的未来方向。我们旨在通过强调如何利用gan来支持临床决策，并有助于更好地理解脑部疾病的结构和功能模式，从而弥合先进的深度学习方法和神经病学研究之间的差距。

Over the years, Machine Learning models have been successfully employed on neuroimaging data for accurately predicting brain age. Deviations from the healthy brain aging pattern are associated to the accelerated brain aging and brain abnormalities. Hence, efficient and accurate diagnosis techniques are required for eliciting accurate brain age estimations. Several contributions have been reported in the past for this purpose, resorting to different data-driven modeling methods. Recently, deep neural networks (also referred to as deep learning) have become prevalent in manifold neuroimaging studies, including brain age estimation. In this review, we offer a comprehensive analysis of the literature related to the adoption of deep learning for brain age estimation with neuroimaging data. We detail and analyze different deep learning architectures used for this application, pausing at research works published to date quantitatively exploring their application. We also examine different brain age estimation frameworks, comparatively exposing their advantages and weaknesses. Finally, the review concludes with an outlook towards future directions that should be followed by prospective studies. The ultimate goal of this paper is to establish a common and informed reference for newcomers and experienced researchers willing to approach brain age estimation by using deep learning models

主观认知下降（SCD）是阿尔茨海默氏病（AD）的临床前阶段，甚至在轻度认知障碍（MCI）之前就发生。渐进式SCD将转换为MCI，并有可能进一步发展为AD。因此，通过神经成像技术（例如，结构MRI）对进行性SCD的早期鉴定对于AD的早期干预具有巨大的临床价值。但是，现有的基于MRI的机器/深度学习方法通​​常会遇到小样本大小的问题，这对相关的神经影像学分析构成了巨大挑战。我们旨在解决本文的主要问题是如何利用相关领域（例如AD/NC）协助SCD的进展预测。同时，我们担心哪些大脑区域与进行性SCD的识别更加紧密相关。为此，我们提出了一个注意引导自动编码器模型，以进行有效的跨域适应，以促进知识转移从AD到SCD。所提出的模型由四个关键组成部分组成：1）用于学习不同域的共享子空间表示的功能编码模块，2）用于自动定义大脑中定义的兴趣障碍区域的注意模块，3）用于重构的解码模块原始输入，4）用于鉴定脑疾病的分类模块。通过对这四个模块的联合培训，可以学习域不变功能。同时，注意机制可以强调与脑部疾病相关的区域。公开可用的ADNI数据集和私人CLAS数据集的广泛实验证明了该方法的有效性。提出的模型直接可以在CPU上仅5-10秒进行训练和测试，并且适用于具有小数据集的医疗任务。

Deep learning has produced state-of-the-art results for a variety of tasks. While such approaches for supervised learning have performed well, they assume that training and testing data are drawn from the same distribution, which may not always be the case. As a complement to this challenge, single-source unsupervised domain adaptation can handle situations where a network is trained on labeled data from a source domain and unlabeled data from a related but different target domain with the goal of performing well at test-time on the target domain. Many single-source and typically homogeneous unsupervised deep domain adaptation approaches have thus been developed, combining the powerful, hierarchical representations from deep learning with domain adaptation to reduce reliance on potentially-costly target data labels. This survey will compare these approaches by examining alternative methods, the unique and common elements, results, and theoretical insights. We follow this with a look at application areas and open research directions.

我们描述了Countersynth，一种诱导标签驱动的扩散变形的条件生成模型，体积脑图像中的标签驱动的生物合理的变化。该模型旨在综合用于下游判别判断性建模任务的反事实训练数据，其中保真度受数据不平衡，分布不稳定性，混淆或缺点的限制，并且在不同的群体中表现出不公平的性能。专注于人口统计属性，我们评估了具有基于体素的形态学，分类和回归条件属性的合成反事实的质量，以及FR \'{e} CHET开始距离。在设计的人口统计不平衡和混淆背景下检查下游歧视性能，我们使用英国Biobank磁共振成像数据来基准测试对这些问题的当前解决方案的增强。我们实现了最先进的改进，无论是整体忠诚和股权。 CounterSynth的源代码可在线获取。

大脑网络将大脑区域之间的复杂连接性描述为图形结构，这为研究脑连接素提供了强大的手段。近年来，图形神经网络已成为使用结构化数据的普遍学习范式。但是，由于数据获取的成本相对较高，大多数大脑网络数据集的样本量受到限制，这阻碍了足够的培训中的深度学习模型。受元学习的启发，该论文以有限的培训示例快速学习新概念，研究了在跨数据库中分析脑连接组的数据有效培训策略。具体而言，我们建议在大型样本大小的数据集上进行元训练模型，并将知识转移到小数据集中。此外，我们还探索了两种面向脑网络的设计，包括Atlas转换和自适应任务重新启动。与其他训练前策略相比，我们的基于元学习的方法实现了更高和稳定的性能，这证明了我们提出的解决方案的有效性。该框架还能够以数据驱动的方式获得有关数据集和疾病之间相似之处的新见解。

深度学习已成为解决不同领域中现实世界中问题的首选方法，部分原因是它能够从数据中学习并在广泛的应用程序上实现令人印象深刻的性能。但是，它的成功通常取决于两个假设：（i）精确模型拟合需要大量标记的数据集，并且（ii）培训和测试数据是独立的且分布相同的。因此，不能保证它在看不见的目标域上的性能，尤其是在适应阶段遇到分布数据的数据时。目标域中数据的性能下降是部署深层神经网络的关键问题，这些网络已成功地在源域中的数据训练。通过利用标记的源域数据和未标记的目标域数据来执行目标域中的各种任务，提出了无监督的域适应（UDA）来对抗这一点。 UDA在自然图像处理，视频分析，自然语言处理，时间序列数据分析，医学图像分析等方面取得了令人鼓舞的结果。在本综述中，作为一个快速发展的主题，我们对其方法和应用程序进行了系统的比较。此外，还讨论了UDA与其紧密相关的任务的联系，例如域的概括和分布外检测。此外，突出显示了当前方法和可能有希望的方向的缺陷。

域适应（DA）最近在医学影像社区提出了强烈的兴趣。虽然已经提出了大量DA技术进行了用于图像分割，但大多数这些技术已经在私有数据集或小公共可用数据集上验证。此外，这些数据集主要解决了单级问题。为了解决这些限制，与第24届医学图像计算和计算机辅助干预（Miccai 2021）结合第24届国际会议组织交叉模态域适应（Crossmoda）挑战。 Crossmoda是无监督跨型号DA的第一个大型和多级基准。挑战的目标是分割参与前庭施瓦新瘤（VS）的后续和治疗规划的两个关键脑结构：VS和Cochleas。目前，使用对比度增强的T1（CET1）MRI进行VS患者的诊断和监测。然而，使用诸如高分辨率T2（HRT2）MRI的非对比度序列越来越感兴趣。因此，我们创建了一个无人监督的跨模型分段基准。训练集提供注释CET1（n = 105）和未配对的非注释的HRT2（n = 105）。目的是在测试集中提供的HRT2上自动对HRT2进行单侧VS和双侧耳蜗分割（n = 137）。共有16支球队提交了评估阶段的算法。顶级履行团队达成的表现水平非常高（最佳中位数骰子 - vs：88.4％; Cochleas：85.7％）并接近完全监督（中位数骰子 - vs：92.5％;耳蜗：87.7％）。所有顶级执行方法都使用图像到图像转换方法将源域图像转换为伪目标域图像。然后使用这些生成的图像和为源图像提供的手动注释进行培训分割网络。

脑电图（EEG）解码旨在识别基于非侵入性测量的脑活动的神经处理的感知，语义和认知含量。当应用于在静态，受控的实验室环境中获取的数据时，传统的EEG解码方法取得了适度的成功。然而，开放世界的环境是一个更现实的环境，在影响EEG录音的情况下，可以意外地出现，显着削弱了现有方法的鲁棒性。近年来，由于其在特征提取的卓越容量，深入学习（DL）被出现为潜在的解决方案。它克服了使用浅架构提取的“手工制作”功能或功能的限制，但通常需要大量的昂贵，专业标记的数据 - 并不总是可获得的。结合具有域特定知识的DL可能允许开发即使具有小样本数据，也可以开发用于解码大脑活动的鲁棒方法。虽然已经提出了各种DL方法来解决EEG解码中的一些挑战，但目前缺乏系统的教程概述，特别是对于开放世界应用程序。因此，本文为开放世界EEG解码提供了对DL方法的全面调查，并确定了有前途的研究方向，以激发现实世界应用中的脑电图解码的未来研究。

Transfer learning aims at improving the performance of target learners on target domains by transferring the knowledge contained in different but related source domains. In this way, the dependence on a large number of target domain data can be reduced for constructing target learners. Due to the wide application prospects, transfer learning has become a popular and promising area in machine learning. Although there are already some valuable and impressive surveys on transfer learning, these surveys introduce approaches in a relatively isolated way and lack the recent advances in transfer learning. Due to the rapid expansion of the transfer learning area, it is both necessary and challenging to comprehensively review the relevant studies. This survey attempts to connect and systematize the existing transfer learning researches, as well as to summarize and interpret the mechanisms and the strategies of transfer learning in a comprehensive way, which may help readers have a better understanding of the current research status and ideas. Unlike previous surveys, this survey paper reviews more than forty representative transfer learning approaches, especially homogeneous transfer learning approaches, from the perspectives of data and model. The applications of transfer learning are also briefly introduced. In order to show the performance of different transfer learning models, over twenty representative transfer learning models are used for experiments. The models are performed on three different datasets, i.e., Amazon Reviews, Reuters-21578, and Office-31. And the experimental results demonstrate the importance of selecting appropriate transfer learning models for different applications in practice.

眼睛的临床诊断是对多种数据模式进行的，包括标量临床标签，矢量化生物标志物，二维底面图像和三维光学相干性层析成像（OCT）扫描。临床从业者使用所有可用的数据模式来诊断和治疗糖尿病性视网膜病（DR）或糖尿病黄斑水肿（DME）等眼部疾病。在眼科医学领域启用机器学习算法的使用需要研究治疗期内所有相关数据之间的关系和相互作用。现有的数据集受到限制，因为它们既不提供数据，也没有考虑数据模式之间的显式关系建模。在本文中，我们介绍了用于研究以上限制的视觉眼睛语义（橄榄）数据集的眼科标签。这是第一个OCT和近IIR眼底数据集，其中包括临床标签，生物标记标签，疾病标签和时间序列的患者治疗信息，来自相关临床试验。该数据集由1268个近红外图像组成，每个图像至少具有49个10月扫描和16个生物标志物，以及4个临床标签和DR或DME的疾病诊断。总共有96张眼睛的数据在至少两年的时间内平均，每只眼睛平均治疗66周和7次注射。我们在医学图像分析中为橄榄数据集进行了橄榄数据集的实用性，并为核心和新兴机器学习范式提供了基准和具体研究方向。

Many clinical and research studies of the human brain require an accurate structural MRI segmentation. While traditional atlas-based methods can be applied to volumes from any acquisition site, recent deep learning algorithms ensure very high accuracy only when tested on data from the same sites exploited in training (i.e., internal data). The performance degradation experienced on external data (i.e., unseen volumes from unseen sites) is due to the inter-site variabilities in intensity distributions induced by different MR scanner models, acquisition parameters, and unique artefacts. To mitigate this site-dependency, often referred to as the scanner effect, we propose LOD-Brain, a 3D convolutional neural network with progressive levels-of-detail (LOD) able to segment brain data from any site. Coarser network levels are responsible to learn a robust anatomical prior useful for identifying brain structures and their locations, while finer levels refine the model to handle site-specific intensity distributions and anatomical variations. We ensure robustness across sites by training the model on an unprecedented rich dataset aggregating data from open repositories: almost 27,000 T1w volumes from around 160 acquisition sites, at 1.5 - 3T, from a population spanning from 8 to 90 years old. Extensive tests demonstrate that LOD-Brain produces state-of-the-art results, with no significant difference in performance between internal and external sites, and robust to challenging anatomical variations. Its portability opens the way for large scale application across different healthcare institutions, patient populations, and imaging technology manufacturers. Code, model, and demo are available at the project website.

最近的智能故障诊断（IFD）的进展大大依赖于深度代表学习和大量标记数据。然而，机器通常以各种工作条件操作，或者目标任务具有不同的分布，其中包含用于训练的收集数据（域移位问题）。此外，目标域中的新收集的测试数据通常是未标记的，导致基于无监督的深度转移学习（基于UDTL为基础的）IFD问题。虽然它已经实现了巨大的发展，但标准和开放的源代码框架以及基于UDTL的IFD的比较研究尚未建立。在本文中，我们根据不同的任务，构建新的分类系统并对基于UDTL的IFD进行全面审查。对一些典型方法和数据集的比较分析显示了基于UDTL的IFD中的一些开放和基本问题，这很少研究，包括特征，骨干，负转移，物理前导等的可转移性，强调UDTL的重要性和再现性 - 基于IFD，整个测试框架将发布给研究界以促进未来的研究。总之，发布的框架和比较研究可以作为扩展界面和基本结果，以便对基于UDTL的IFD进行新的研究。代码框架可用于\ url {https:/github.com/zhaozhibin/udtl}。

在急诊室（ER）环境中，中风分类或筛查是一个普遍的挑战。由于MRI的慢速吞吐量和高成本，通常会进行快速CT而不是MRI。在此过程中通常提到临床测试，但误诊率仍然很高。我们提出了一个新型的多模式深度学习框架，深沉的中风，以通过识别较小的面部肌肉不协调的模式来实现计算机辅助中风的存在评估，并使怀疑急性环境中的中风的患者无能为力。我们提出的深雷克斯（Deepstroke）在中风分流器中容易获得一分钟的面部视频数据和音频数据，用于局部面部瘫痪检测和全球语音障碍分析。采用了转移学习来减少面部侵蚀偏见并提高普遍性。我们利用多模式的横向融合来结合低水平和高级特征，并为关节训练提供相互正则化。引入了新型的对抗训练以获得无身份和中风的特征。与实际急诊室患者进行的视频ADIO数据集进行的实验表明，与分类团队和ER医生相比，中风的表现要优于最先进的模型，并且取得更好的性能，比传统的敏感性高出10.94％，高7.37％的精度高出7.37％。当特异性对齐时，中风分类。同时，每个评估都可以在不到六分钟的时间内完成，这表明该框架的临床翻译潜力很大。

阿尔茨海默氏病的准确诊断和预后对于开发新疗法和降低相关成本至关重要。最近，随着卷积神经网络的进步，已经提出了深度学习方法，以使用结构MRI自动化这两个任务。但是，这些方法通常缺乏解释性和泛化，预后表现有限。在本文中，我们提出了一个旨在克服这些局限性的新型深框架。我们的管道包括两个阶段。在第一阶段，使用125个3D U-NET来估计整个大脑的体voxelwise等级得分。然后将所得的3D地图融合，以构建一个可解释的3D分级图，以指示结构水平的疾病严重程度。结果，临床医生可以使用该地图来检测受疾病影响的大脑结构。在第二阶段，分级图和受试者的年龄用于使用图卷积神经网络进行分类。基于216名受试者的实验结果表明，与在不同数据集上进行AD诊断和预后的最新方法相比，我们的深框架的竞争性能。此外，我们发现，使用大量的U-NET处理不同的重叠大脑区域，可以提高所提出方法的概括能力。

机器学习系统通常假设训练和测试分布是相同的。为此，关键要求是开发可以概括到未经看不见的分布的模型。领域泛化（DG），即分销概括，近年来引起了越来越令人利益。域概括处理了一个具有挑战性的设置，其中给出了一个或几个不同但相关域，并且目标是学习可以概括到看不见的测试域的模型。多年来，域概括地区已经取得了巨大进展。本文提出了对该地区最近进步的首次审查。首先，我们提供了域泛化的正式定义，并讨论了几个相关领域。然后，我们彻底审查了与域泛化相关的理论，并仔细分析了泛化背后的理论。我们将最近的算法分为三个类：数据操作，表示学习和学习策略，并为每个类别详细介绍几种流行的算法。第三，我们介绍常用的数据集，应用程序和我们的开放源代码库进行公平评估。最后，我们总结了现有文学，并为未来提供了一些潜在的研究主题。

Wearable sensor-based human activity recognition (HAR) has emerged as a principal research area and is utilized in a variety of applications. Recently, deep learning-based methods have achieved significant improvement in the HAR field with the development of human-computer interaction applications. However, they are limited to operating in a local neighborhood in the process of a standard convolution neural network, and correlations between different sensors on body positions are ignored. In addition, they still face significant challenging problems with performance degradation due to large gaps in the distribution of training and test data, and behavioral differences between subjects. In this work, we propose a novel Transformer-based Adversarial learning framework for human activity recognition using wearable sensors via Self-KnowledgE Distillation (TASKED), that accounts for individual sensor orientations and spatial and temporal features. The proposed method is capable of learning cross-domain embedding feature representations from multiple subjects datasets using adversarial learning and the maximum mean discrepancy (MMD) regularization to align the data distribution over multiple domains. In the proposed method, we adopt the teacher-free self-knowledge distillation to improve the stability of the training procedure and the performance of human activity recognition. Experimental results show that TASKED not only outperforms state-of-the-art methods on the four real-world public HAR datasets (alone or combined) but also improves the subject generalization effectively.

The primary goal of this work is to study the effectiveness of an unsupervised domain adaptation approach for various applications such as binary classification and anomaly detection in the context of Alzheimer's disease (AD) detection for the OASIS datasets. We also explore image reconstruction and image synthesis for analyzing and generating 3D structural MRI data to establish performance benchmarks for anomaly detection. We successfully demonstrate that domain adaptation improves the performance of AD detection when implemented in both supervised and unsupervised settings. Additionally, the proposed methodology achieves state-of-the-art performance for binary classification on the OASIS-1 dataset.