... glands, and blood vessels Tell the difference between cysts (fluid-filled sacs) and solid tumors Ultrasound may help diagnose medical conditions that involve many parts of the body, such as the: Heart and heart valves Blood vessels Organs in the abdomen (belly), including the liver , gallbladder , pancreas , or spleen Organs in the pelvis , including the urinary tract , and male and female reproductive organs Thyroid and parathyroid glands Kidneys Breasts Brain, spine, and ...