What is Vascular Ultrasound Imaging?
Ultrasound or sonography involves the sending of sound waves through the body. Those sound waves are reflected off the internal organs. The reflections are then interpreted by special instruments that subsequently create an image of anatomic parts. No ionizing radiation (x-ray) is involved in ultrasound imaging.
An ultrasound image is a useful way of evaluating the body’s circulatory system. Ultrasound images are captured in real-time, so they can help radiologists monitor the blood flow to organs and tissues throughout the body, as well as evaluate the placement and success of repair, such as after arterial bypass surgery. With ultrasound images, radiologists can locate and identify blockages (stenosis) and abnormalities like blood clots, plaque or emboli, and help plan for their effective treatment.
What are some common uses of the procedure?
Ultrasound imaging of the body’s veins and arteries can help the radiologist see and evaluate blockages to blood flow, such as clots in veins and plaque in arteries. With knowledge about the arterial blood flow gained from an ultrasound image, the radiologist can often determine whether a patient is a good candidate for a procedure like angioplasty. Ultrasound images may also be used to plan or review the success of procedures that graft or bypass blood vessels—such as renal (relating to the kidney) artery bypass. Ultrasound of the veins may reveal blood clots that require treatment such as anticoagulant therapy (blood thinner), or filters to prevent clots from traveling to the lungs (embolism).
How should I prepare for the procedure?
What does the equipment look like?
The transducer passes the image to the ultrasound machine and from there to a viewing monitor. The radiologist or ultrasonographer watches this screen during an examination and captures representative images for storage. Often, the patient is able to see it as well. Blood flow also produces sound that can be heard with Doppler ultrasound. You may also hear the sounds.
How does the procedure work?
The ultrasound transducer functions as both a loudspeaker (to create the sounds) and a microphone (to record them). When the transducer is pressed against the skin, it directs a stream of inaudible, high-frequency sound waves into the body. As the sound waves echo from the body’s fluids and tissues, the sensitive microphone in the transducer records tiny changes in the sound’s pitch and direction. These signature waves are instantly measured and displayed by a computer, which in turn creates a real-time picture on the monitor. Still frames of the moving picture are “frozen” to capture a series of images. Blood flow changes the pitch of the sound beam; this Doppler effect can be heard or detected on the image as color or displayed graphically.
How is the procedure performed?
When the examination is complete, the patient may be asked to dress and wait while the ultrasound images are reviewed, either on film or on a monitor. Often, though, the sonographer or radiologist is able to review the ultrasound images in real time as they are acquired, and the patient can be released immediately.
What will I experience during the procedure?
Who interprets the results and how do I get them?
What are the benefits vs. risks?
- Ultrasound scanning is non-invasive (no needles or injections) and usually painless.
- Ultrasound is widely available and easy to use.
- Ultrasound uses no ionizing radiation.
- Ultrasound images can demonstrate structure, movement and function in the body’s blood vessels in real time.
- For standard diagnostic ultrasound there are no known harmful effects on humans.
What are the limitations of Vascular Ultrasound Imaging?
- Vessels deep in the body are harder to see than superficial vessels. Specialized equipment may be necessary.
- Calcifications that occur as a result of atherosclerosis may obstruct the ultrasound beam.
- Sometimes the ultrasound cannot tell the difference between a blood vessel that is closed or very nearly closed because the weak volume of blood flow produces a weak signal.