In the context of medical imaging and machine learning, one of the most pressing challenges is the effective adaptation of pre-trained models to specialized medical contexts. Despite the availability of advanced pre-trained models, their direct application to the highly specialized and diverse field of medical imaging often falls short due to the unique characteristics of medical data. This study provides a comprehensive analysis on the performance of various fine-tuning methods applied to pre-trained models across a spectrum of medical imaging domains, including X-ray, MRI, Histology, Dermoscopy, and Endoscopic surgery. We evaluated eight fine-tuning strategies, including standard techniques such as fine-tuning all layers or fine-tuning only the classifier layers, alongside methods such as gradually unfreezing layers, regularization based fine-tuning and adaptive learning rates. We selected three well-established CNN architectures (ResNet-50, DenseNet-121, and VGG-19) to cover a range of learning and feature extraction scenarios. Although our results indicate that the efficacy of these fine-tuning methods significantly varies depending on both the architecture and the medical imaging type, strategies such as combining Linear Probing with Full Fine-tuning resulted in notable improvements in over 50% of the evaluated cases, demonstrating general effectiveness across medical domains. Moreover, Auto-RGN, which dynamically adjusts learning rates, led to performance enhancements of up to 11% for specific modalities. Additionally, the DenseNet architecture showed more pronounced benefits from alternative fine-tuning approaches compared to traditional full fine-tuning. This work not only provides valuable insights for optimizing pre-trained models in medical image analysis but also suggests the potential for future research into more advanced architectures and fine-tuning methods.

针对医学影像和机器学习领域的一个主要挑战是如何有效地将预训练模型适应于专门的医学背景。本研究对应用于X光、MRI、组织学、皮肤镜检和内窥镜手术等不同医学影像领域的多种微调方法在预训练模型上的性能进行了全面的分析。结果显示，结合线性探测和全面微调等策略在50%以上的情况下能够明显提高性能，动态调整学习率的自动RGN方法在特定模态下能够提高11%的性能。此外，与传统的全面微调相比，DenseNet结构对替代的微调方法表现出更为显著的优势。本研究不仅为优化医学影像分析中的预训练模型提供了有价值的洞见，而且建议未来研究可以探索更先进的架构和微调方法。

医学图像分类中的迁移学习的微调策略的比较