cdfi refers to the blood flow signal in ultrasonography, cdfi shows that the blood flow signal is rich, including physiological (such as the carotid artery, etc.) and pathological (such as hyperthyroidism, tumors, etc.), need to be specifically analyzed. 1. physiological: such as the carotid artery in the ultrasound cdfi signal rich in blood flow, is the body’s normal physiological phenomenon. 2. Pathological: when hyperthyroidism, thyroid ultrasound will suggest that the thyroid gland is rich in blood flow signals, thyroid function and other tests can assist in a clear diagnosis; tumors, when the tumor grows faster, its blood supply will be richer, ultrasound will suggest that the cdfi signal is rich in blood flow, and biopsy can assist in a clear diagnosis. The rich blood flow signal of cdfi can be physiological or pathologic, if it is pathologic, it should be consulted immediately and treated as early as possible.