The role of ultrasound in breast care has expanded considerably over the past 30 years. While in its infancy, it was used mainly to distinguish cystic from solid masses, it has evolved to be an essential component of state-of-the-art breast care for the breast surgeon. Currently, it is essential for work-up of breast symptoms or mammographic abnormalities, and is the preferred modality for image-guided procedures. Breast ultrasound is unique from ultrasound of other areas in the body in that it requires correlation of ultrasound findings with mammogram and physical examination. Major advantages of ultrasound over other breast imaging modalities include lack of exposure to ionizing radiation as well as patient comfort.
The American College of Radiology defines several indications for breast ultrasound (Table 5-1). Ultrasound is the modality of choice for work-up of a palpable mass in a woman less than age 30, due to density of the breast on mammography. Breast tissue becomes less dense and more fatty as a woman ages. Adipose or fatty tissue is visualized well on mammography, so mammographic screening is most effective in older women with fatty breasts. In younger patients with dense breasts, mammography is much less sensitive, since dense breast tissue appears opaque and less radiolucent, making it more difficult to identify masses or asymmetric densities that can be signs of malignancy. When performing breast ultrasound, density is not a factor that affects the sensitivity. In addition, it is the preferred test for a palpable mass in a pregnant woman. Ultrasound can also be used to evaluate findings seen on mammography. For mammographic abnormalities including a mass, developing focal asymmetric density, or area of architectural distortion, sonography can further characterize the area and guide biopsy.1 Breast masses detected on self-examination or clinical examination in women over age 30, focal breast thickening, breast pain, or nipple discharge should first be evaluated mammographically. A negative mammogram should be followed with ultrasound for a symptomatic area or region of clinical concern.2 For any lesion of concern, image-guided biopsy is the standard of care for diagnosis as opposed to surgical excisional biopsy (if technically feasible).3
Table 5-1 Indications for Breast Ultrasound ||Download (.pdf)
Table 5-1 Indications for Breast Ultrasound
|Evaluation of a palpable mass or other signs/symptoms in the breast|
|Evaluation of abnormalities on other imaging studies (such as mammography or MRI)|
|Initial imaging of a palpable mass in women under 30 (who are not at high risk for breast cancer) and in lactating/pregnant women|
|Evaluation of problems with breast implants|
|Evaluation of lesions suspicious for malignancy (microcalcifications or architectural distortion) in the setting of dense fibroglandular tissue|
|Guidance of breast biopsy or interventional procedure|
|Treatment planning for radiation therapy|
|Screening for occult cancer as a supplement to mammography in certain populations of women who are not candidates for MRI|
|Identification and biopsy of abnormal axillary lymph nodes|
Breast ultrasound can be ...