1. Ultrasonography plays an important role in early diagnosis and screening of liver cancer. For example, ultrasound-guided cytology and tissue biopsy are effective and reliable methods for diagnosis and differential diagnosis of primary liver cancer and histologic typing, and they can also be used to understand the degree of differentiation of the cancer cells and judge the prognosis. 2. The sensitivity of sonogram for metastatic liver tumor is about 86% and the specificity can reach 99%. The detection rate can be improved if multiple images are used together. 3.Ultrasonic diagnosis of liver cysts has high sensitivity, easy to find cysts with diameter less than 1cm or even smaller, and the accuracy rate can reach 98%. 4.Ultrasonic diagnosis is easy to diagnose typical segmental non-homogeneous fatty liver, in which individual types such as mass type need to be differentiated from hemangioma and hepatocellular carcinoma. 5.Color Doppler ultrasound can provide important information about blood perfusion in primary liver cancer, which can help to confirm the clinical diagnosis. 6.Gray scale ultrasound can clearly show the dilated bile ducts inside and outside the liver, thus it can play a very important role in the differential diagnosis of obstructive jaundice. Other common diseases: uterine fibroids, ovarian cysts, prostate hypertrophy, etc. can be detected and treated at an early stage by ultrasonography, and it is recommended that you have a routine ultrasound checkup once every six months to one year.