Breast ultrasound is a complementary study of mammography. In contrast epidemiologic studies show a high incidence of breast cancer following mammography screening. Procedures to evaluate mammography based on magnetic resonance imaging exist too. Some more advanced tests include ultrasound and mammography. Digital mammography is also utilized in stereotactic biopsy. Services include&colon; emergency department, sleep lab, bone density testing, mammography, ultrasound and MRI. Approximately one-third of malignant calcification clusters detected at screening mammography already have an invasive focus. Ultrasound, mammography and bone mineral densitometry are located at the Branson site. In many cases, ductal carcinoma is asymptomatic, and detected as abnormal results on mammography. CAD is used in screening mammography (X-ray examination of the female breast). In October 2006, Nixon was diagnosed with breast cancer during a routine mammography. During the procedure, the breast is compressed using a dedicated mammography unit. Implants can interfere with mammography (breast x-rays images). Estimates of overdiagnosis associated with mammography have ranged from 1% to 54%. Estimates of the numbers of cancers missed by mammography are usually around 20%.