CDFI is a color Doppler ultrasound examination, and little blood flow signal means that the blood supply inside or around the lesion is not rich and the blood flow signal is little. Malignant tumors are usually richer in blood flow signals around and within the lesion, and can show abundant blood flow signals such as rings and clusters, such as renal cell carcinoma and thyroid cancer. On the other hand, most benign lesions are not rich in flow signals and usually have punctate flow signals, such as abscesses, cysts, and so on. It is important to note that some benign lesions can also have abundant flow signals, such as hyperthyroidism. Therefore, with the combination of 2D ultrasound sonogram performance and color Doppler examination, the benign or malignant nature of the lesion can be more accurately determined. The presence of reduced blood flow signal where there was blood flow signal, or the presence of abundant blood flow signal where there was no blood flow signal, can indirectly determine the nature of the lesion.