Due to complex experimental settings, missing values are common in biomedical data. To handle this issue, many methods have been proposed, from ignoring incomplete instances to various data imputation approaches. With the recent rise of deep neural networks, the field of missing data imputation has oriented towards modelling of the data distribution. This paper presents an approach based on Monte Carlo dropout within (Variational) Autoencoders which offers not only very good adaptation to the distribution of the data but also allows generation of new data, adapted to each specific instance. The evaluation shows that the imputation error and predictive similarity can be improved with the proposed approach.
University of North Carolina at Chapel Hill（北卡罗来纳大学教堂山分校）
Deep Learning (DL) methods have dramatically increased in popularity in recent years. While its initial success was demonstrated in the classification and manipulation of image data, there has been significant growth in the application of DL methods to problems in the biomedical sciences. However, the greater prevalence and complexity of missing data in biomedical datasets present significant challenges for DL methods. Here, we provide a formal treatment of missing data in the context of Variational Autoencoders (VAEs), a popular unsupervised DL architecture commonly utilized for dimension red…
In longitudinal data a response variable is measured over time, or under different conditions, for a cohort of individuals. In many situations all intended measurements are not available which results in missing values. If the missing value is never followed by an observed measurement, this leads to dropout pattern. The missing values could be in the response variable, the covariates or in both. The missingness mechanism is termed non-random when the probability of missingness depends on the missing value and may be on the observed values. In this case the missing values should be considered i…
Aalto University（阿尔托大学）；HUS Helsinki University Hospital（赫尔辛基大学医院）；University of Helsinki（赫尔辛基大学）
Longitudinal datasets measured repeatedly over time from individual subjects, arise in many biomedical, psychological, social, and other studies. A common approach to analyse high-dimensional data that contains missing values is to learn a low-dimensional representation using variational autoencoders (VAEs). However, standard VAEs assume that the learnt representations are i.i.d., and fail to capture the correlations between the data samples. We propose the Longitudinal VAE (L-VAE), that uses a multi-output additive Gaussian process (GP) prior to extend the VAE's capability to learn structured…
A Hybrid Computational Intelligence Framework for scRNA-seq Imputation: Integrating scRecover and Random Forests
University of Technology Sydney, Australia（悉尼科技大学）；University of Sydney, Australia（悉尼大学）；Asia Pacific International College (APIC), Parramatta, NSW, Australia（亚太国际学院）；Lincoln Institute of Higher Education (LIHE), Sydney, Australia（林肯高等教育研究所）；The Institute of International Studies (TIIS), Sydney, Australia（国际研究学院）
The mixed effects model for repeated measures (MMRM) has been widely used for the analysis of longitudinal clinical data collected at a number of fixed time points. We propose a robust extension of the MMRM for skewed and heavy-tailed data on basis of the multivariate skew-t distribution, and it includes the multivariate normal, t, and skew-normal distributions as special cases. An efficient Markov chain Monte Carlo algorithm is developed using the monotone data augmentation and parameter expansion techniques. We employ the algorithm to perform controlled pattern imputations for sensitivity an…
A Large-Scale Comparative Analysis of Imputation Methods for Single-Cell RNA Sequencing Data
RPTU University Kaiserslautern-Landau, Department of Computer Science（莱茵-瓦尔登堡大学凯撒斯劳滕-兰道分校计算机科学系）；German Research Center for Artificial Intelligence (DFKI GmbH)（德国人工智能研究中心（DFKI GmbH））；Graduate School of Informatics, Osaka Metropolitan University（大阪 Metropolitan 大学信息研究生院）；intelligentX GmbH (intelligentX.com)（intelligentX GmbH（intelligentX.com））
Gene Regulatory Network Inference in the Presence of Dropouts: a Causal View
Carnegie Mellon University（卡内基梅隆大学）；Mohamed bin Zayed University of Artificial Intelligence（穆罕默德·本·扎耶德人工智能大学）；Broad Institute of MIT and Harvard（麻省理工学院与哈佛大学博德研究所）
Fed-ReMasker: Federated Tabular Imputation under Feature-Level Missingness
ARTORG Center for Biomedical Engineering Research University of Bern（伯尔尼大学生物医学工程研究中心）；Graduate School for Cellular and Biomedical Sciences University of Bern（伯尔尼大学细胞与生物医学科学研究生院）
BACKGROUND: As databases grow larger, it becomes harder to fully control their collection, and they frequently come with missing values: incomplete observations. These large databases are well suited to train machine-learning models, for instance for forecasting or to extract biomarkers in biomedical settings. Such predictive approaches can use discriminative -- rather than generative -- modeling, and thus open the door to new missing-values strategies. Yet existing empirical evaluations of strategies to handle missing values have focused on inferential statistics. RESULTS: Here we conduct a s…
Seoul National University（首尔国立大学）；Samsung Electronics Co. Ltd.（三星电子有限公司）；Seoul National University College of Medicine（首尔国立大学医学院）
Electronic health records (EHRs) have contributed to the computerization of patient records and can thus be used not only for efficient and systematic medical services, but also for research on biomedical data science. However, there are many missing values in EHRs when provided in matrix form, which is an important issue in many biomedical EHR applications. In this paper, we propose a two-stage framework that includes missing data imputation and disease prediction to address the missing data problem in EHRs. We compared the disease prediction performance of generative adversarial networks (GA…
Polytechnique Montréal（蒙特利尔理工学院）；Télécom Paristech University（巴黎电信学院）；Montréal Heart Institute（蒙特利尔心脏研究所）；Université de Montréal（蒙特利尔大学）
Semantic segmentation is a crucial task in biomedical image processing, which recent breakthroughs in deep learning have allowed to improve. However, deep learning methods in general are not yet widely used in practice since they require large amount of data for training complex models. This is particularly challenging for biomedical images, because data and ground truths are a scarce resource. Annotation efforts for biomedical images come with a real cost, since experts have to manually label images at pixel-level on samples usually containing many instances of the target anatomy (e.g. in his…
Tabular LLMs for Interpretable Few-Shot Alzheimer's Disease Prediction with Multimodal Biomedical Data
University of Pennsylvania（宾夕法尼亚大学）；Stony Brook University（石溪大学）；University of North Carolina at Chapel Hill（北卡罗来纳大学教堂山分校）；Medical University of South Carolina（南卡罗来纳医科大学）；Cedars-Sinai Medical Center（西格拉姆山医疗中心）
Texas A&M University（得克萨斯农工大学）；TEES-AgriLife Center for Bioinformatics & Genomic Systems Engineering（TEES-农业生命中心生物信息学与基因组系统工程中心）
Missing values frequently arise in modern biomedical studies due to various reasons, including missing tests or complex profiling technologies for different omics measurements. Missing values can complicate the application of clustering algorithms, whose goals are to group points based on some similarity criterion. A common practice for dealing with missing values in the context of clustering is to first impute the missing values, and then apply the clustering algorithm on the completed data. We consider missing values in the context of optimal clustering, which finds an optimal clustering ope…
