ABSTRACT
Objectives It remains difficult to characterize pain in knee joints with risk of osteoarthritis solely by radiographic findings. We sought to understand if advanced machine learning methods such as deep neural networks can be used to predict and identify the structural features that are associated with knee pain.
Methods We constructed a convolutional Siamese network to associate MRI scans obtained on subjects from the Osteoarthritis Initiative (OAI) with frequent unilateral knee pain (n=1,529) comparing their knee with frequent pain to the contralateral knee without pain. The Siamese network architecture enabled pairwise learning of information from two-dimensional (2D) sagittal intermediate-weighted turbo spin echo slices obtained from similar locations on both knees. Class activation mapping (CAM) was utilized to create saliency maps, which highlighted the regions that were most associated with knee pain. The MRI scans and the CAMs of each subject were reviewed by a radiologist to identify the presence of abnormalities within the model-predicted regions of high association.
Results Using 10-fold cross validation, our model achieved an area under curve (AUC) value of 0.808. When individuals whose knee WOMAC pain scores were not discordant were excluded, model performance increased to 0.853. The radiologist review revealed that about 86% of the cases that were predicted correctly had effusion-synovitis within the regions that were most associated with pain.
Conclusions This study demonstrates a proof of principle that deep learning can be applied to assess knee pain from MRI scans.
Footnotes
Updated model