The CT manifestations of bronchiectasis in the upper lobe of the left lung are bronchial wall thickening, mucus embedding or air-liquid plane, and bronchial contour changes. 1. Bronchial wall thickening: If columnar bronchiectasis is present in the upper lobe of the left lung, bronchial wall thickening will be seen on CT examination of the lung. The bronchial dilatation will have small rounded arterioles attached to it. If the bronchial axis is parallel to the scanning plane, a double-track sign will appear, and if the scanning plane is perpendicular to the bronchial axis, an imprinting sign will appear. 2. Mucus embedded: left upper lobe bronchiectasis will also appear in CT examination of cystic bronchiectasis, at this time, the distal bronchus will appear cystic dilatation, and the formation of honeycomb clusters of small cystic cavities, the cystic cavity will be filled with mucus. If the cystic lumen is infected, there will be air-liquid planes. 3. Changes in bronchial contour: in the case of bronchial dilatation of the upper lobe of the left lung, the diameter of the tube is irregularly dilated, and part of the lumen will appear similar to a pearl necklace or varicose veins. When some of the bronchial dilatation is severe, not only the distal bronchus will appear rod-like dilatation, but also the proximal bronchus or the whole bronchus will appear dilatation. Prompt medical attention is recommended for bronchiectasis of the upper lobe of the left lung.