A Doppler ultrasound study may be part of an ultrasound examination. Doppler ultrasound is a special ultrasound technique that evaluates blood velocity 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.
Doppler ultrasound images can help the physician to evaluate:
- Blockages to blood flow (such as clots).
- Narrowing of vessels (which may be caused by plaque).
- Tumors and congenital malformation.
With knowledge about the speed and volume of blood flow gained from a Doppler ultrasound image, the physician can often determine whether a patient is a good candidate for a procedure like angioplasty.
courtesy of radiologyinfo.org
Most Doppler ultrasound scanning is noninvasive (no needles or injections) and is usually painless.