Automated whole-breast ultrasound: advancing the performance of breast cancer screening

Screening has been successful in the early detection of some cancers, including cervical, colon, and breast. However, the success in mortality reduction by screening mammography has been limited in women with mammographically dense tissue. Magnetic resonance imaging has been used with success in the screening of high-risk women, but it is expensive. Also, its use in a screening program requires a contrast medium that has not been tested in humans or animals for long-term safety in humans or animals for repeated biannual or annual injections. Ultrasound also has the potential to be an ideal screening tool because it is relatively inexpensive and requires no injected contrast or ionizing radiation. However, the relatively poor conspicuity of some cancers by hand scanning and the considerable radiologist time necessary limit its use. Automated whole-breast ultrasound (AWBU) allows the radiologist to read the images quickly, at a convenient time, while being free from doing the scan. Two-dimensional AWBU uses a cine loop of axial images, with <1 mm image spacing, which are read on a high-resolution monitor to improve the conspicuity of small cancers. A blinded study of this system combined with screening mammography showed that adding AWBU both doubles overall cancer detection and triples the 1 cm-or-less invasive cancers found in dense-breasted women. As expected, mammography had a significantly greater detection rate of ductal carcinoma in situ than AWBU. As yet no clinical studies of other AWBU systems have been published.