Ultrasonography is most commonly used to obtain an image of soft tissue. In its two-dimensional form, ultrasonography is used extensively for abdominal (kidneys, liver, and gallbladder) and thoracic (heart) exams. It is useful in animals to diagnose pregnancy, as the fetal heartbeat(s) cannot be found early in pregnancy. Another type of diagnostic ultrasound, Doppler, is used in vascular diagnosis to assess blood flow. Other areas, such as the eyes, thyroid, breast, and testicles, can be imaged by ultrasound as well.