Fig. 5: Representative chest radiographs overlaid with class activation maps (CAM) showing the active area of convolutional neural network (CNN).

a The inferior lung field of the left lung is overlaid by CAM, which reveals a patchy density (white arrow). The CNN noted that this case had a “patchy consolidation” sign, while the other 24 abnormal signs were absent. b The middle and lower fields of the left lung are overlaid by CAM, which reveals a pulmonary nodule (white arrow). The CNN indicated that this case had a “nodule” sign, while the other 24 abnormal signs were absent. c The upper right lung is overlaid by CAM. The CNN indicated that this case has a “pneumothorax” label. The radiologists confirmed this finding and found visible visceral pleural margins (white arrow), but there was no lung texture outside this line. The other 24 abnormal signs were absent. d The lower right lung is overlaid by CAM. The CNN indicated that this case has a “hydrothorax” sign. The radiologists confirmed this finding and identified an air-fluid level (white arrow). e The upper field and lower field of the left lung are overlaid by CAMs. The CNN indicated that this case had “patchy consolidation” and “pleural effusion” signs. The other 23 abnormal signs were absent. The radiologists confirmed CNN’s findings (white arrows).