Closing the Generalization Gap of Cross-silo Federated Medical Image Segmentation
It addresses data privacy and efficiency issues in medical imaging by improving model generalization, though it is incremental as it builds on existing FL methods.
The paper tackles the generalization gap in cross-silo federated learning for medical image segmentation caused by non-iid data and client drift, proposing FedSM to close this gap compared to centralized training for the first time.
Cross-silo federated learning (FL) has attracted much attention in medical imaging analysis with deep learning in recent years as it can resolve the critical issues of insufficient data, data privacy, and training efficiency. However, there can be a generalization gap between the model trained from FL and the one from centralized training. This important issue comes from the non-iid data distribution of the local data in the participating clients and is well-known as client drift. In this work, we propose a novel training framework FedSM to avoid the client drift issue and successfully close the generalization gap compared with the centralized training for medical image segmentation tasks for the first time. We also propose a novel personalized FL objective formulation and a new method SoftPull to solve it in our proposed framework FedSM. We conduct rigorous theoretical analysis to guarantee its convergence for optimizing the non-convex smooth objective function. Real-world medical image segmentation experiments using deep FL validate the motivations and effectiveness of our proposed method.