Middle lobe atelectasis, i.e., atelectasis in the middle lobe of the right lung, has a CT presentation with the possibility of middle lobe hyperdense shadows, displaced interlobar fissures, and diaphragmatic elevation. Lung atelectasis is a collapse of lung tissue due to bronchial obstruction, space-occupying lesions compressing the lungs, adhesions, scarring, and other causes. Because it affects gas exchange, symptoms such as chest tightness, dyspnea, dry cough and hemoptysis may occur. Middle lobe atelectasis is caused by the occlusion of the alveoli in the middle lobe, which results in increased density and reduced volume, and is characterized by a dense shadow with the tip of the middle lobe pointing to the hilum, denser bronchial vascular bundles than normal, displacement of the interlobar fissures to the middle lobe, and elevation of the diaphragm on CT. If there is a suspicion of middle lobe atelectasis, it is necessary to go to the hospital for chest CT examination and bronchoscopy examination, except for the cause of the mass in the lumen of the trachea, etc., so that the professional doctor can give a clear result.