Rethinking Autoencoders for Medical Anomaly Detection from A Theoretical Perspective

Fuente: arXiv
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Main Authors: Cai, Yu, Chen, Hao, Cheng, Kwang-Ting
Format: Preprint
Published: 2024
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author Cai, Yu
Chen, Hao
Cheng, Kwang-Ting
author_facet Cai, Yu
Chen, Hao
Cheng, Kwang-Ting
contents Medical anomaly detection aims to identify abnormal findings using only normal training data, playing a crucial role in health screening and recognizing rare diseases. Reconstruction-based methods, particularly those utilizing autoencoders (AEs), are dominant in this field. They work under the assumption that AEs trained on only normal data cannot reconstruct unseen abnormal regions well, thereby enabling the anomaly detection based on reconstruction errors. However, this assumption does not always hold due to the mismatch between the reconstruction training objective and the anomaly detection task objective, rendering these methods theoretically unsound. This study focuses on providing a theoretical foundation for AE-based reconstruction methods in anomaly detection. By leveraging information theory, we elucidate the principles of these methods and reveal that the key to improving AE in anomaly detection lies in minimizing the information entropy of latent vectors. Experiments on four datasets with two image modalities validate the effectiveness of our theory. To the best of our knowledge, this is the first effort to theoretically clarify the principles and design philosophy of AE for anomaly detection. The code is available at \url{https://github.com/caiyu6666/AE4AD}.
format Preprint
id arxiv_https___arxiv_org_abs_2403_09303
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Rethinking Autoencoders for Medical Anomaly Detection from A Theoretical Perspective
Cai, Yu
Chen, Hao
Cheng, Kwang-Ting
Machine Learning
Computer Vision and Pattern Recognition
Medical anomaly detection aims to identify abnormal findings using only normal training data, playing a crucial role in health screening and recognizing rare diseases. Reconstruction-based methods, particularly those utilizing autoencoders (AEs), are dominant in this field. They work under the assumption that AEs trained on only normal data cannot reconstruct unseen abnormal regions well, thereby enabling the anomaly detection based on reconstruction errors. However, this assumption does not always hold due to the mismatch between the reconstruction training objective and the anomaly detection task objective, rendering these methods theoretically unsound. This study focuses on providing a theoretical foundation for AE-based reconstruction methods in anomaly detection. By leveraging information theory, we elucidate the principles of these methods and reveal that the key to improving AE in anomaly detection lies in minimizing the information entropy of latent vectors. Experiments on four datasets with two image modalities validate the effectiveness of our theory. To the best of our knowledge, this is the first effort to theoretically clarify the principles and design philosophy of AE for anomaly detection. The code is available at \url{https://github.com/caiyu6666/AE4AD}.
title Rethinking Autoencoders for Medical Anomaly Detection from A Theoretical Perspective
topic Machine Learning
Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2403.09303