Imaging of the breast is undertaken as part of a comprehensive evaluation of this organ, integrating the patient's history, clinical signs, and symptoms. Radiography of the breast is known as mammography, or radiomammography. When used periodically in asymptomatic patients, this is called screening mammography. When imaging is targeted to patients with signs or symptoms of breast cancer, it is referred to as diagnostic breast imaging and usually is a tailored evaluation consisting of some combination of mammography and other techniques described later. Using the integrated approach, it is often possible to make an accurate diagnosis nonoperatively, and treatment may be individualized according to each patient's needs. The primary purpose of breast imaging is to detect breast carcinoma. A secondary purpose is to evaluate benign disease, such as cyst formation, infection, implant complication, and trauma.
Before the 1980s, when breast imaging was much less widely used, the proportion of surgery for benign breast disease was higher, and treatment for breast carcinoma was initiated at later stages of the disease than at present. Breast imaging has increased the detection of tumors smaller than those found on clinical breast examination and has enabled patients to avoid unnecessary surgery.
The outcome of earlier diagnosis and treatment, however, is yet to be proven. Mortality from breast cancer has remained fairly stable for several decades in spite of the introduction and popularization of screening mammography. Debate continues as to the efficacy of routine breast screening in certain age groups. It is almost universally acknowledged that women over 50 years of age benefit from periodic screening mammography. Several large population studies have shown a decrease in mortality of around 30% in this group. However, controversy continues concerning the value of screening mammography for women under the age of 50 years. Because breast cancer has a lower prevalence in this age group, the impediment to mass screening is largely economic; that is, the number of lives saved relative to dollars spent must be justified. Another difference is that in younger women the breast parenchyma is more often dense and nodular. This condition decreases the sensitivity for detection for carcinoma and leads to more false-negative and false-positive results.
Besides a decrease in mortality, a second benefit of earlier diagnosis is that patients with breast carcinoma are afforded more treatment options; lumpectomy with radiation therapy is an option to mastectomy in many patients.
Mammography has been in common use since about 1980, and breast ultrasonography has been the most often used adjunctive technique during this time. The major contribution of ultrasonography has been its effectiveness in distinguishing cystic lesions from solid masses. Sonography has, therefore, helped to avoid unnecessary surgery, because asymptomatic simple cysts do not require intervention. Ultrasonography, together with mammography, is also used to help characterize solid lesions as benign, indeterminate, or suspicious.
Magnetic resonance (MR) imaging of the breast can be used in selected patients. Image-guided needle biopsy of ...