Deep Nearest Neighbors for Anomaly Detection in Chest X-Rays
Paper in proceeding, 2024

Identifying medically abnormal images is crucial to the diagnosis procedure in medical imaging. Due to the scarcity of annotated abnormal images, most reconstruction-based approaches for anomaly detection are trained only with normal images. At test time, images with large reconstruction errors are declared abnormal. In this work, we propose a novel feature-based method for anomaly detection in chest x-rays in a setting where only normal images are provided during training. The model consists of lightweight adaptor and predictor networks on top of a pre-trained feature extractor. The parameters of the pre-trained feature extractor are frozen, and training only involves fine-tuning the proposed adaptor and predictor layers using Siamese representation learning. During inference, multiple augmentations are applied to the test image, and our proposed anomaly score is simply the geometric mean of the k-nearest neighbor distances between the augmented test image features and the training image features. Our method achieves state-of-the-art results on two challenging benchmark datasets, the RSNA Pneumonia Detection Challenge dataset, and the VinBigData Chest X-ray Abnormalities Detection dataset. Furthermore, we empirically show that our method is robust to different amounts of anomalies among the normal images in the training dataset. The code is available at: https://github.com/XixiLiu95/deep-kNN-anomaly-detection.

Anomaly detection

Siamese representation learning

k-Nearest neighbor

Author

Xixi Liu

Chalmers, Electrical Engineering, Signal Processing and Biomedical Engineering

Jennifer Alvén

Chalmers, Electrical Engineering, Signal Processing and Biomedical Engineering

Ida Häggström

Chalmers, Electrical Engineering, Signal Processing and Biomedical Engineering

Christopher Zach

Chalmers, Electrical Engineering, Signal Processing and Biomedical Engineering

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

03029743 (ISSN) 16113349 (eISSN)

Vol. 14349 LNCS 293-302
9783031456756 (ISBN)

14th International Workshop on Machine Learning in Medical Imaging, MLMI 2023
Vancouver, Canada,

Subject Categories

Subatomic Physics

Cardiac and Cardiovascular Systems

Computer Science

Radiology, Nuclear Medicine and Medical Imaging

Computer Vision and Robotics (Autonomous Systems)

Medical Image Processing

DOI

10.1007/978-3-031-45676-3_30

More information

Latest update

11/22/2023