Streak shadow, clinically known as pulmonary striae, is a pathognomonic description on imaging of both lungs. Streaks in the lungs are usually a pathognomonic description of striated, high-density lesions in both lungs on radiographs and CT scans. Lung striae may be the result of incomplete absorption of inflammatory lesions in the lungs, and the imaging may suggest scarring of the lungs after the inflammatory disease has healed, such as in some patients with bacterial pneumonia and tuberculosis. Streaks in the lungs may also be caused by various reasons and idiopathic interstitial fibrosis, suggesting that the lungs have a diffuse fibrosis pathology, which is a more serious disease that requires other related tests to make a comprehensive judgment and a clear diagnosis. The presence of streaks in the lungs should be treated promptly, and under the guidance of the doctor to improve the examination, clear diagnosis and treatment.