Selecting the Best Optimizers for Deep Learning based Medical Image Segmentation

TL;DR

This paper investigates the effectiveness of optimizer strategies, particularly cyclic learning and momentum rates, for deep learning-based cardiac image segmentation, demonstrating a new method that improves accuracy and generalization.

Contribution

The paper introduces a cyclic optimizer combining learning rate and momentum rate, showing improved segmentation performance over existing optimizers in medical imaging.

Findings

Proposed optimizer outperforms others with over 2% dice metric improvement.

Cyclic optimization enhances generalization in cardiac image segmentation.

Method achieves similar or lower computational cost than existing approaches.

Abstract

The goal of this work is to identify the best optimizers for deep learning in the context of cardiac image segmentation and to provide guidance on how to design segmentation networks with effective optimization strategies. Adaptive learning helps with fast convergence by starting with a larger learning rate (LR) and gradually decreasing it. Momentum optimizers are particularly effective at quickly optimizing neural networks within the accelerated schemes category. By revealing the potential interplay between these two types of algorithms (LR and momentum optimizers or momentum rate (MR) in short), in this article, we explore the two variants of SGD algorithms in a single setting. We suggest using cyclic learning as the base optimizer and integrating optimal values of learning rate and momentum rate. We investigated the relationship of LR and MR under an important problem of medical image segmentation of cardiac structures from MRI and CT scans. We conducted experiments using the cardiac imaging dataset from the ACDC challenge of MICCAI 2017, and four different architectures shown to be successful for cardiac image segmentation problems. Our comprehensive evaluations demonstrated that the proposed optimizer achieved better results (over a 2\% improvement in the dice metric) than other optimizers in deep learning literature with similar or lower computational cost in both single and multi-object segmentation settings. We hypothesized that combination of accelerated and adaptive optimization methods can have a drastic effect in medical image segmentation performances. To this end, we proposed a new cyclic optimization method (\textit{CLMR}) to address the efficiency and accuracy problems in deep learning based medical image segmentation. The proposed strategy yielded better generalization in comparison to adaptive optimizers.