Ultrasound Imaging

Description

Ultrasound imaging (sonography) uses high-frequency sound waves to view soft tissues such as muscles and internal organs. Because ultrasound images are captured in real-time, they can show movement of the body's internal organs as well as blood flowing through blood vessels.

In an ultrasound exam, a hand-held transducer is placed against the skin. The transducer sends out high frequency sound waves that reflect off of body structures. The returning sound waves, or echoes, are displayed as an image on a monitor. The image is based on the frequency and strength (amplitude) of the sound signal and the time it takes to return from the patient to the transducer. Unlike with an x-ray, there is no ionizing radiation exposure with this test.

Procedures

Ultrasound imaging is used in many types of examinations and procedures. Some examples include

• Doppler ultrasound (to visualize blood flow through a blood vessel)
• Bone sonography (to diagnose osteoporosis)
• Echocardiogram (to view the heart)
• Fetal ultrasound (to view the fetus in pregnancy)
• Ultrasound-guided biopsies
• Doppler fetal heart rate monitors (to listen to the fetal heart beat)

Risks/Benefits

Ultrasound imaging has been used for over 20 years and has an excellent safety record. It is non-ionizing radiation, so it does not have the same risks as x-rays or other types of ionizing radiation.

Even though there are no known risks of ultrasound imaging, it can produce effects on the body. When ultrasound enters the body, it heats the tissues slightly. In some cases, it can also produce small pockets of gas in body fluids or tissues (cavitation). The long-term effects of tissue heating and cavitation are not known.

Because of the particular concern for fetal exposures, national and international organizations have advocated prudent use of ultrasound imaging. Furthermore, the use of diagnostic ultrasound for non-medical purposes such as fetal keepsake videos has been discouraged.

Information for Patients

• FDA Consumer Update on Ultrasound
• FDA Consumer Update on Fetal Keepsake Videos
• Health Canada Information on Fetal Ultrasound for Keepsake Videos

Information for Professionals

• American Institute for Ultrasound in Medicine (AIUM)

Laws, Regulations & Performance Standards

• Manufacturers of electronic radiation emitting products sold in the United States are responsible for compliance with the Federal Food, Drug and Cosmetic Act (FFDCA), Chapter V, Subchapter C - Electronic Product Radiation Control.

Manufacturers of ultrasound imaging products are responsible for compliance with all applicable requirements of Title 21 Code of Federal Regulations (Subchapter J, Radiological Health) Parts 1000 through 1005:

1000 - General

1002 - Records and Reports

1003 - Notification of defects or failure to comply

1004 - Repurchase, repairs, or replacement of electronic products

1005 - Importation of electronic products

There are no federal radiation safety performance standards for diagnostic ultrasound.

Because they are medical devices, ultrasound imaging equipment must also comply with the medical device regulations. For more information, see Getting to Market with a Medical Device.

Industry Guidance

• Information for Manufacturers Seeking Marketing Clearance of Diagnostic Ultrasound Systems and Transducers (September 9, 2008)
• Procedures for Importing Electronic Products which Emit Radiation [PDF] (May 28, 1981)
• Form FDA-2877 Declaration for Products Subject to Radiation Control Standards [PDF]

Other Resources

• Device Advice: Does the Product Emit Radiation? (July 28, 2006)
• Frequently Asked Questions for Manufacturers of Electronic Products that Emit Radiation (April 25, 2006)
• Regulated Industry: Reports and Recordkeeping
• FDA eSubmitter
• Regulated Industry: Imports & Exports