The scope of ultrasound examination is very broad and can be said to be all-encompassing. However, some organs and tissues are sensitive to ultrasound examination, and some parts are not sensitive to ultrasound examination. The sensitive areas are: 1) circulatory system, such as heart; 2) digestive system, such as liver, gallbladder, spleen, pancreas; 3) urinary system, such as kidney, ureter, bladder; 4) male reproductive system, such as testes, epididymis; 5) female reproductive system, such as uterus, ovaries, fetus; 6) superficial organs, including thyroid, breast, salivary gland, eye, superficial soft tissue, abdominal wall, chest wall, etc.; 7) blood vessels, including peripheral blood vessels, limbs, etc. 7. blood vessels, including peripheral blood vessels, arteries and veins of the extremities, and arteries and veins of the neck. 8. lymphatic system, deep and superficial lymph nodes, etc., which are all sensitive to ultrasound examination. There are also those that are less sensitive to ultrasonography, such as the pericardium, large blood vessels of the heart, gastrointestinal tract, seminal glands, adrenal glands, fallopian tubes, large blood vessels of the abdomen, and musculoskeletal, nerve, and lung areas.