What is Ultrasound Imaging of the Breast?
Ultrasound is safe and painless, and produces pictures of the inside of the body using sound waves. Ultrasound imaging, also called ultrasound scanning or sonography, involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the probe through the gel into the body. The transducer collects the sounds that bounce back and a computer then uses those sound waves to create an image. Ultrasound examinations do not use ionizing radiation (as used in x-rays), thus there is no radiation exposure to the patient. 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 a noninvasive medical test that helps physicians diagnose and treat medical conditions.
Doppler ultrasound, also called color Doppler ultrasonography, is a special ultrasound technique that allows the physician to see and evaluate blood flow through arteries and veins in the abdomen, arms, legs, neck and/or brain (in infants and children) or within various body organs such as the liver or kidneys.
Ultrasound imaging of the breast produces a picture of the internal structures of the breast.
During a breast ultrasound examination, the sonographer or physician performing the test may use Doppler techniques to evaluate blood flow or lack of flow in any breast mass. In some cases, this may provide additional information as to the cause of the mass.
What are some common uses of the procedure?
Determining the Nature of a Breast Abnormality
The primary use of breast ultrasound is to help diagnose breast abnormalities detected by a physician during a physical exam (such as a lump) and to characterize potential abnormalities seen on mammography or breast magnetic resonance imaging (MRI).
Ultrasound imaging can help to determine if an abnormality is solid (which may be a non-cancerous lump of tissue or a cancerous tumor), fluid-filled (such as a benign cyst) or both cystic and solid.
Doppler ultrasound is used to assess blood supply in breast lesions.
Supplemental Breast Cancer Screening
Mammography is the only screening tool for breast cancer that is known to reduce deaths due to breast cancer through early detection. Even so, mammograms do not detect all breast cancers. Some breast lesions and abnormalities are not visible or are difficult to interpret on mammograms. Breasts that are considered dense have a lot of glandular and connective tissues and not much fatty tissue, and that makes cancer harder to detect.
Many studies have shown that ultrasound and magnetic resonance imaging (MRI) can help supplement mammography by detecting breast cancers that may not be visible with mammography. Your doctor can help you determine if either of these tests is appropriate for you. MRI is more sensitive than ultrasound in depicting breast cancer, but MRI may not be available to all women. If screening MRI is performed, then screening ultrasound is not needed, though ultrasound may be used to characterize and biopsy abnormalities seen on MRI. When ultrasound is used for screening, abnormalities not visible with mammography may be identified, including some that may require biopsy. Many of the abnormalities found with screening breast ultrasound are not cancer (false positives). See the Breast Cancer Screening page for more information.
Ultrasound can be offered as a screening tool for women who:
are at high risk for breast cancer and unable to undergo an MRI examination.
are pregnant or should not be exposed to x-rays (which are necessary for a mammogram).
have increased breast density — when the breasts have a lot of glandular and connective tissue and not much fatty tissue (see the Dense Breasts page for more information).
Ultrasound-guided Breast Biopsy
When an ultrasound examination reveals a suspicious breast abnormality, a physician may choose to perform an ultrasound-guided biopsy. Because ultrasound provides real-time images, it is often used to guide biopsy procedures. An ultrasound exam will usually need to be performed before the biopsy in order to plan the procedure and to determine if this method of biopsy can be used.
What are the benefits vs. risks?
Benefits
Most ultrasound scanning is noninvasive (no needles or injections).
Occasionally, an ultrasound exam may be temporarily uncomfortable, but it should not be painful.
Ultrasound is widely available, easy-to-use and less expensive than other imaging methods.
Ultrasound imaging is extremely safe and does not use any ionizing radiation.
Ultrasound scanning gives a clear picture of soft tissues that do not show up well on x-ray images.
Ultrasound provides real-time imaging, making it a good tool for guiding minimally invasive procedures such as needle biopsies and fluid aspiration.
Ultrasound imaging can help detect lesions in women with dense breasts.
Ultrasound may help detect and classify a breast lesion that cannot be interpreted adequately through mammography alone.
Using ultrasound, physicians are able to determine that many areas of clinical concern are due to normal tissue (such as fat lobules) or benign cysts. For most women 30 years of age and older, a mammogram will be used together with ultrasound. For women under age 30, ultrasound alone is often sufficient to determine whether an area of concern needs a biopsy or not.
Risks
For standard diagnostic ultrasound, there are no known harmful effects on humans.
Interpretation of a breast ultrasound examination may lead to additional procedures such as follow-up ultrasound and/or aspiration or biopsy. Many of the areas thought to be of concern turn out to be non-cancerous (false positives).
What are the limitations of Ultrasound Imaging of the Breast?
Ultrasound is one of the tools used in breast imaging, but it does not replace annual mammography.
Many cancers are not visible on ultrasound. Many calcifications seen on mammography cannot be seen on ultrasound. Some early breast cancers only show up as calcifications on mammography. MRI findings that are due to cancer are not always seen with ultrasound.
Biopsy may be recommended to determine if a suspicious abnormality is cancer or not.
Most suspicious findings on ultrasound that require biopsy are not cancers.
Many facilities do not offer ultrasound screening, even in women with dense breasts, and the procedure may not be covered by some insurance plans.
It is important to choose a facility with expertise in breast ultrasound, preferably one where the radiologists specialize in breast imaging. Ultrasound depends on the abnormality being recognized at the time of the scan as it is a “real-time” examination. This requires experience and good equipment. One measure of a facility’s expertise in breast ultrasound can be found in its ACR accreditation status. Check the facilities in your area by searching the ACR-accredited facilities database.