A Weakly Supervised Framework for COVID 19 Classification and Lesion Localization From Chest CT
Accurate and rapid diagnosis of COVID 19 suspected cases plays a crucial role in timely quarantine and medical treatment. Developing a deep learning based model for automatic COVID 19 diagnosis on chest CT is helpful to counter the outbreak of SARS CoV 2. A weakly supervised deep learning framework was developed using 3D CT volumes for COVID 19 classification and lesion localization. For each patient, the lung region was segmented using a pre trained UNet; then the segmented 3D lung region was fed into a 3D deep neural network to predict the probability of COVID 19 infectious; the COVID 19 lesions are localized by combining the activation regions in the classification network and the unsupervised connected components. 499 CT volumes were used for training and 131 CT volumes were used for testing. Our algorithm obtained 0.959 ROC AUC and 0.976 PR AUC. When using a probability threshold of 0.5 to classify COVID positive and COVID negative, the algorithm obtained an accuracy of 0.901, a positive predictive value of 0.840 and a very high negative predictive value of 0.982. The algorithm took only 1.93 seconds to process a single patient's CT volume using a dedicated GPU. Our weakly supervised deep learning model can accurately predict the COVID 19 infectious probability and discover lesion regions in chest CT without the need for annotating the lesions for training. The easily trained and high performance deep learning algorithm provides a fast way to identify COVID 19 patients, which is beneficial to control the outbreak of SARS CoV 2. The developed deep learning software is available at https:/github.com/sydney0zq/covid 19 detection.
IEEE Transactions on Medical Imaging