Echo nodules are the signals of echoes obtained on the computer screen of ultrasound when using ultrasound to detect subcutaneous masses of soft tissues, according to which certain properties of nodules can be determined. There is a law of echoes, the greater the difference in density between the two material interfaces, the stronger the echoes will be, while the closer the density is between the two material interfaces, the weaker the echoes will be. So when detecting certain masses, such as thyroid masses. Once the mass has obvious calcification inside, and the density difference with the surrounding tissue is relatively large, you will get a strong echogenic nodule of, and once the density of the nodule and the surrounding normal tissue than, the relative strength is not too large, or close, the obtained is weak echogenic, is the so-called weak echogenic nodule.