Unsupervised Dual Adversarial Learning for Anomaly Detection in Colonoscopy Video Frames
This addresses the need for cheaper automated colonoscopy analysis by reducing annotation costs, though it is incremental as it builds on existing anomaly detection methods.
The paper tackles the problem of detecting polyp-containing frames in colonoscopy videos by treating them as anomalies from a distribution of polyp-free frames, achieving state-of-the-art results on the dataset.
The automatic detection of frames containing polyps from a colonoscopy video sequence is an important first step for a fully automated colonoscopy analysis tool. Typically, such detection system is built using a large annotated data set of frames with and without polyps, which is expensive to be obtained. In this paper, we introduce a new system that detects frames containing polyps as anomalies from a distribution of frames from exams that do not contain any polyps. The system is trained using a one-class training set consisting of colonoscopy frames without polyps -- such training set is considerably less expensive to obtain, compared to the 2-class data set mentioned above. During inference, the system is only able to reconstruct frames without polyps, and when it tries to reconstruct a frame with polyp, it automatically removes (i.e., photoshop) it from the frame -- the difference between the input and reconstructed frames is used to detect frames with polyps. We name our proposed model as anomaly detection generative adversarial network (ADGAN), comprising a dual GAN with two generators and two discriminators. We show that our proposed approach achieves the state-of-the-art result on this data set, compared with recently proposed anomaly detection systems.