What is Arterial Ultrasound Imaging?
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 (x-ray). 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.
Ultrasound imaging is usually a painless medical test that helps physicians diagnose and treat medical conditions.
A Doppler ultrasound study may be part of an arterial 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.

What are some common uses of the procedure?
The most common reason for an arterial ultrasound exam is to test for peripheral arterial disease. It is estimated that peripheral arterial disease (PAD) affects 8 to 12 million people in the United States. While many patients suffer from symptoms of claudication and rest pain, others have no obvious symptoms. Patients may dismiss vague cramping, fatigue or numbness and not seek medical attention until the disease is more advanced and producing severe claudication. It is important to be able to identify patients at an early stage of the disease since they also have a higher incidence of heart disease and stroke.
Standard tests such as Ankle Brachial Index, Arterial Duplex Scanning and Segmental Pressures, Waveforms and Exercise provide information regarding the presence, location and severity of PAD. Tests are also available for evaluating and following bypass grafts, aneurysms, hemoaccess grafts and vascular trauma.

How should I prepare for the procedure?
You should wear comfortable, loose-fitting clothing for your ultrasound exam. You will need to remove all clothing and jewelry in the area to be examined.
You may be asked to wear a gown during the procedure.

What does the equipment look like?
Ultrasound scanners consist of a console containing a computer and electronics, a video display screen and a transducer that is used to scan the body. The transducer is a small hand-held device that resembles a microphone, attached to the scanner by a cord. The transducer sends out a high frequency sound wave and then listens for a returning sound wave or "echo".
The ultrasound image is immediately visible on a nearby screen that looks much like a computer or television monitor. The image is created based on the amplitude (strength), frequency and time it takes for the sound signal to return from the patient to the transducer.
An example of the ultrasound equipment that may be used is shown at the top of this page.

How does the procedure work?
Ultrasound imaging is based on the same principles involved in the sonar used by bats, ships and fishermen. When a sound wave strikes an object, it bounces backward, or echoes. By measuring these echo waves it is possible to determine how far away the object is and its size, shape, consistency (whether the object is solid, filled with fluid, or both) and uniformity.
In medicine, ultrasound is used to detect changes in appearance and function of organs, tissues, or abnormal masses, such as tumors.
In an ultrasound examination, a transducer both sends the sound waves and records the echoing waves. 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 bounce off of internal organs, 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. These live images are usually recorded on videotape and one or more frames of the moving pictures are typically captured as still images.
Doppler ultrasound, a special application of ultrasound, measures the direction and speed of blood cells as they move through vessels. The movement of blood cells causes a change in pitch of the reflected sound waves (Doppler effect). A computer collects and processes the sounds and creates graphs or pictures that represent the flow of blood through the blood vessels.

How is the procedure performed?
These tests utilize duplex ultrasound, a combination of imaging and doppler flow velocity measurement, and blood pressure measurement. Exercise testing involves some form of stress that works the muscles of the lower extremities such as walking on a treadmill or performing heel raises while standing. Exercise testing can provide information regarding disease that does not produce symptoms at rest by measuring how far the pressure at the ankle drops and how quickly it returns to resting levels after the exercise.
Testing is usually staged. When a patient with suspected PAD is referred to Health Diagnostics, the Ankle Brachial Index (ABI) is calculated. If the ABI is normal, an exercise test is performed. If the results of exercise are normal, testing is terminated. If either or both of these tests are abnormal, then further testing is indicated. Segmental Pressures and Arterial Duplex Scanning are then performed to assess the severity and location of the disease.

Patients with suspected PAD and those with more advanced symptoms such as claudication, rest pain, ulceration or gangrene can be referred to Health Diagnostics with an order such as “lower extremity arterial exam”. Key information required by the laboratory includes a designation for “arterial” testing and the relevant symptoms consistent with PAD. A Health Diagnostics registered vascular sonographer will then perform the appropriate tests indicated for each patient.

What will I experience during and after the procedure?
Most ultrasound examinations are painless, fast and easy.
After you are positioned on the examination table, the radiologist or sonographer will spread some warm gel on your skin and then press the transducer firmly against your body, moving it back and forth over the area of interest until the desired images are captured. There may be varying degrees of discomfort from pressure as the transducer is pressed against the area being examined.
If scanning is performed over an area of tenderness, you may feel pressure or minor pain from the procedure.
If a Doppler ultrasound study is performed, you may actually hear pulse-like sounds that change in pitch as the blood flow is monitored and measured.
Once the imaging is complete, the gel will be wiped off your skin.
After an ultrasound exam, you should be able to resume your normal activities.

Who interprets the results and how do I get them?
A radiologist, a physician specifically trained to supervise and interpret radiology examinations, will analyze the images and send a signed report to your primary care or referring physician, who will share the results with you.

What are the benefits vs. risks?
Benefits

• Ultrasound scanning is noninvasive (no needles or injections) and is usually painless.
• Ultrasound is widely available, easy-to-use and less expensive than other imaging methods.
• Ultrasound imaging uses no ionizing radiation.
• Ultrasound scanning gives a clear picture of soft tissues that do not show up well on x-ray images.
• Ultrasound causes no health problems and may be repeated as often as is necessary if medically indicated.
• Venous ultrasound helps to detect blood clots in the veins of the legs before they become dislodged and pass to the lungs. It can also show the movement of blood within blood vessels.
• Compared to venography, which requires injecting contrast material into a vein, venous ultrasound is nearly as accurate for detecting blood clots in the calf and almost fully as accurate in finding clots in veins of the thigh.
  

Risks

• For standard diagnostic ultrasound there are no known harmful effects on humans.

Which Health Diagnostics facilities offer this service?