Breast ultrasound is a noninvasive (the skin is not pierced) procedure used to assess the breasts. Ultrasound technology allows quick visualization of the breast tissue. Ultrasound may also be used to assess blood flow to areas inside the breasts. The examination is often used along with mammography.
Breast ultrasound uses a handheld probe called a transducer that sends out ultrasonic sound waves at a frequency too high to be heard. When the transducer is placed on the breast at certain locations and angles, the ultrasonic sound waves move through the skin and other breast tissues. The sound waves bounce off the tissues like an echo and return to the transducer. The transducer picks up the reflected waves, which are then converted into an electronic picture of the breasts.
Different types of body tissues affect the speed at which sound waves travel. Sound travels the fastest through bone tissue, and moves most slowly through air. The speed at which the sound waves are returned to the transducer, as well as how much of the sound wave returns, is translated by the transducer as different types of tissue.
Prior to the procedure, clear, water-based gel is applied to the skin to allow for smooth movement of the transducer over the skin and to eliminate air between the skin and the transducer.
By using an additional mode of ultrasound technology during an ultrasound procedure, blood flow within the breast can be assessed. An ultrasound transducer capable of assessing blood flow contains a Doppler probe. The Doppler probe within the transducer evaluates the velocity and direction of blood flow in the vessel by making the sound waves audible. The degree of loudness of the audible sound waves indicates the rate of blood flow within a blood vessel. Absence or faintness of these sounds may indicate an obstruction of blood flow.
Ultrasound may be safely used during pregnancy or in the presence of allergies to contrast dye, because no radiation or contrast dyes are used.
More recent ultrasound technologies, such as three-dimensional (3D) and four-dimensional (4D) ultrasound, tissue harmonic imaging (uses the harmonic signal generated by tissue itself), ultrasound contrast agents, and ultrasound elastography (low-frequency vibration technique used to evaluate movement of breast lesions), show promise for diagnosing cancerous breast lesions in a noninvasive manner.
Related procedures that may be performed to evaluate breast problems include mammography, breast biopsy, and breast scan. Please see these procedures for more information.