Ultrasound Imaging

Ultrasound imaging is a noninvasive medical test that helps physicians diagnose and treat medical conditions. Ultrasound imaging, also called ultrasound scanning or sonography, involves exposing part of the body to high-frequency sound waves to produce pictures of the inside of the body. Ultrasound exams do not use ionizing radiation (as used in x-rays). Because ultrasound images are captured in real-time, they can show the structure and movement of the body's internal organs, as well as blood flowing through blood vessels.

A Doppler ultrasound study may be part of an ultrasound examination. Doppler ultrasound is a special ultrasound technique that evaluates blood as it flows through a blood vessel, including the body's major arteries and veins in the abdomen, arms, legs and neck.

There are three types of Doppler ultrasound:

• Color Doppler uses a computer to convert Doppler measurements into an array of colors to visualize the speed and direction of blood flow through a blood vessel.
• Power Doppler is a newer technique that is more sensitive than color Doppler and capable of providing greater detail of blood flow, especially when blood flow is little or minimal. Power Doppler, however, does not help the radiologist determine the direction of blood flow, which may be important in some situations.

• Spectral Doppler. Instead of displaying Doppler measurements visually, Spectral Doppler displays blood flow measurements graphically, in terms of the distance traveled per unit of time.