CDFI refers to color Doppler flow imaging, i.e., color ultrasound, which can be used to screen for disease in a variety of organs and systems, and CDFI without significant blood flow signal is mostly normal, indicating that no significant lesion exists in the corresponding examination site. In clinical conditions, the presence of blood flow signal mainly includes cardiovascular lesions, as well as inflammation, bleeding, tumors and other lesions of various organs: 1, cardiovascular lesions: such as vascular occlusion, stenosis, thrombosis, calcification and other lesions, as well as angiomas, venous reflux disorders and other diseases, can be detected through ultrasound examination, CDFI visible obvious blood flow signal; 2, lesions of various organs: including the thyroid, breast, ovary, liver, heart and other organs, as well as the gallbladder, heart and other organs. The presence of inflammation, bleeding, stones, polyps, tumors and other lesions in the thyroid, breast, ovary, liver, heart and other organs, as well as the gallbladder, ureter, bladder, urethra and other parts of the body, can also be manifested as obvious blood flow signals visible on CDFI. In addition, CDFI results can also show the growth of tumor. If the examination report shows no obvious blood flow signal or less blood flow signal, it indicates that the tumor is growing slowly; if it shows rich blood flow signal, it indicates that the tumor has nutrition supply and grows faster. In addition, ultrasound can also be used in pregnancy examination. If the report indicates that no obvious blood flow signal is seen, there is no need to worry if it is the first examination. If there is no blood flow and no fetal heartbeat after 7 weeks, it indicates an empty gestational sac and should be treated accordingly under the guidance of the doctor.