Accurate, automated classification of radiographic knee osteoarthritis severity using a novel method of deep learning: Plug-in modules

초록

Background: Fine-grained classification deals with data with a large degree of similarity such as cat or bird species and similarly, knee osteoarthritis severity classification (Kellgren-Lawrence [KL] grading) is one of the fine-grained classification tasks. Recently, plug-in module (PIM) that can be integrated into convolutional neural network-based or Transformer-based networks has been shown to provide strong discriminative regions for fine-grained classification with results that outperformed the previous deep learning models. PIM utilizes each pixel of an image as independent feature and can subsequently, better classify images with minor differences. It was hypothesized that as one of the fine-grained classification tasks, knee osteoarthritis severity may be well classified using PIMs. The aim of the study was to develop this automated knee osteoarthritis classification model. Methods: A deep learning model that classifies knee osteoarthritis severity of a radiograph was developed utilizing PIMs. A retrospective analysis on prospectively collected data was performed. The model was trained and developed using the Osteoarthritis Initiative dataset and was subsequently tested on an independent dataset, Multicenter Osteoarthritis Study (test set size: 17040). The final deep learning model was designed through an ensemble of four different PIMs. Results: The accuracies of the model were 85%, 46%, 69%, 82%, and 93% for KL grade 0, 1, 2, 3, and 4, respectively with the overall accuracy of 76.0%. Conclusions: The ensemble of PIMs could classify knee osteoarthritis severity using simple radiographs with a fine accuracy. Although improvements will be needed in the future, the model has been proven to have the potential to be clinically useful.

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