The pre-training and fine-tuning paradigm has become prominent in transfer learning. For example, if the model is pre-trained on ImageNet and then fine-tuned to PASCAL, it can significantly outperform that trained directly on PASCAL. While ImageNet pre-training has shown enormous success, it is formed in 2D and the learned features are for classification tasks. Therefore, when transferring to more diverse tasks, like 3D image segmentation, its performance is inevitably compromised due to the deviation from the original ImageNet context. A significant challenge lies in the lack of large, annotated 3D datasets rivaling the scale of ImageNet for model pre-training. To overcome this challenge, we make two contributions. Firstly, we construct ImageNetCT-9K that comprises 9,262 three-dimensional computed tomography (CT) volumes with high-quality, per-voxel annotations. Secondly, we develop a suite of models that is supervised pre-trained on our ImageNetCT-9K. Our preliminary analyses indicate that the model trained only with 20 CT volumes, 640 masks, and 40 GPU hours has a transfer learning ability similar to the model trained with 5,050 CT volumes and 1,152 GPU hours. More importantly, the transfer learning ability of supervised models can further scale up with larger annotated datasets (i.e., SPT), achieving significantly better performance than all existing 3D models, irrespective of their pre-training methodologies or sources. We hope this study can facilitate collective efforts in constructing larger 3D vision datasets and more releases of supervised pre-trained models. Our code is attached as supplementary and will be publicly available.
How Well Do Supervised Models Transfer to 3D Image Segmentation?
Wenxuan Li Alan Yuille Zongwei Zhou