Filling defect is a descriptive term used in imaging reports such as arterial embolism, tumors, and gastrolithiasis can cause filling defects. A filling defect is a defect in the contrast agent caused by a space-occupying lesion at the exam site that cannot be filled by the contrast agent when imaging under CT and MRI during the imaging process. If angiography is done, filling defects can occur in occupations caused by emboli of thrombus, such as pulmonary embolism, cerebral infarction, etc. Filling defects can also occur in occupational lesions caused by tumors and gastrolithiasis in gastrointestinal angiography. Filling defect is a descriptive term, and needs to be combined with clinical manifestations and medical history to arrive at the most accurate judgment, and relevant treatment according to medical advice.