Doppler Ultrasound: What is it?
A Doppler ultrasound test is a non-invasive form of medical imaging that uses high-frequency sound waves to measure the velocity and direction of blood flow through major arteries and other blood vessels. These tests may also be referred to as vascular ultrasound imaging. These sound waves are recorded by a small hand-held device called a transducer, which is operated by a sonographer. As blood cells ping sound waves back to the transducer, real-time images are recorded by a computer to be examined by a radiologist.
Doppler ultrasound tests are usually performed in a radiology clinic as an outpatient procedure, taking about 10-15 minutes to complete. Types of Doppler ultrasound imaging used by radiology clinics include:
Continuous wave Doppler scans: These scans send continuous waves of high-frequency sound waves through the body, allowing the transducer to record fast-moving blood cells moving through blood vessels in the body.
Duplex ultrasound: Duplex ultrasounds map a graph of arterial channels by measuring blood flow speed and direction through the blood vessels. These graphs can help doctors get a more complete picture of the veins in the body, and any blockage that may be occurring. To help measure the ankle-brachial index, patients may be asked to wear blood pressure cuffs during a duplex ultrasound. The ankle-brachial index is a key test in screening for peripheral artery disease (PAD), as it measures blood flow to the limbs.
Color Doppler ultrasound: A computer changes regular Doppler ultrasound sound waves into color images, showing a clear picture of blood flow through blood vessels in the body. Transcranial Doppler tests are specialized color Doppler tests that measure blood flow to the brain. During a transcranial Doppler ultrasound, the transducer is placed in the head and neck area. These tests are just as painless and non-invasive as other types of ultrasound imaging tests.