Improved CycleGAN with application to COVID-19 classification

Asaf Bar-El, Dana Cohen, Noa Cahan, Hayit Greenspan

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


One of the major problems in medical imaging is the shortage of pathology data. In most cases, the acquisition of labeled data is expensive and usually involves manual labeling by a skilled medical expert. Because of this, most medical imaging tasks suffer from a severe class imbalance with a bias towards non-pathological classes, resulting in reduced performance. The recent growth in the use of generative adversarial networks and their ability to generate synthetic data shows great promise for reducing the class imbalance problem. In this work we introduce the GC-CycleGAN model, a general method for CycleGAN factorization, utilizing Grad-CAMs as auxiliary data in the CycleGAN model to generate synthetic images. Our novel approach utilizes Grad-CAMs ability to describe class activation and uses it for improved network classification, rather than as a visualization tool. The spread of the COVID-19 pandemic is affecting the lives of millions worldwide. If proven effective, automated COVID-19 detection from chest X-ray images can be a supportive step in the fight against COVID-19. However, the task of COVID-19 classification suffers greatly from the class imbalance problem. Using the GC-CycleGAN method, we demonstrate in this work the ability to balance a heavily imbalanced dataset for the task of COVID-19 vs. non-COVID-19 pneumonia X-ray classification. We show improved results over two baselines and the COVID-Net model.

Original languageEnglish
Title of host publicationMedical Imaging 2021
Subtitle of host publicationImage Processing
EditorsIvana Isgum, Bennett A. Landman
ISBN (Electronic)9781510640214
StatePublished - 2021
EventMedical Imaging 2021: Image Processing - Virtual, Online, United States
Duration: 15 Feb 202119 Feb 2021

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
ISSN (Print)1605-7422


ConferenceMedical Imaging 2021: Image Processing
Country/TerritoryUnited States
CityVirtual, Online


FundersFunder number
Ministry of Science and Technology, Israel3-16467


    • COVID-19 Classification
    • CycleGAN
    • Generative Networks
    • Grad-CAM
    • Synthetic Data Augmentation


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