Medical ultrasound is one of the most widely used imaging technologies for diagnosing and directing treatment for many different conditions and diseases. It uses the same basic technology as sonar that bats, ships and fishermen use: a transducer is placed against the skin, sending pulses of inaudible, high-frequency sound waves that are recorded by a computer when they bounce off internal structures such as organs and fluids.
This information is then displayed as real-time moving images on a monitor. The technologist uses gel to minimize friction between the transducer and the patient’s skin, and to ensure that sound waves can travel easily. A computer creates the image based on the loudness (amplitude), pitch (frequency) and how long it takes for the signals to bounce back from the body structures. This information helps the technologist determine if an object is solid or filled with liquid, and what its shape and consistency is.
An example of a diagnostic ultrasound is an echocardiogram, commonly known as an echo, which assesses the structure and function of a patient’s heart. The ultrasound can identify problems such as valve leakage, pericardial effusion and aortic regurgitation. An echocardiogram can also help doctors decide whether a patient needs to be admitted to the hospital for further evaluation and/or treatment.
Another type of diagnostic ultrasound is elastography, which measures and displays the relative stiffness of tissues, such as tumors or liver fibrosis, using color-coded maps that overlay anatomical images. It can also be used to identify blood flow and velocity within vessels, such as in the carotid arteries, and in the liver.