“Mammography has allowed us to see today with the eyes of tomorrow,“1 said Edward Lewison in 1980. Since the genesis of breast imaging, advances in imaging for cancer screening, diagnosis, and response assessment have ranged from ultrasound, positron emission mammography (PEM), diffusion contrast-enhanced magnetic resonance imaging (DCE-MRI), and breast-specific gamma imaging (BSGI) with technetium (99mTc)-sestamibi. Now, more than ever, advances in imaging of the breast are even better than Lewison and his contemporaries could have imagined.
The basic radiological techniques for screening, diagnosis, and assessment of response to treatment are based on the anatomy of the tumor. Members of the oncology team are already familiar with mammography, in which machines produce low-dose x-rays that allow better contrast and detection of cancer than the higher amounts used in the standard chest x-ray. Digital mammography, in which the breast image is recorded electronically, is now finding its place in the day-to-day activities of oncology teams in hospitals and oncology practices. An analysis of subgroups in the Digital Mammographic Imaging Screening Trial (DMIST), which involved more than 40,000 women, showed that although the overall diagnostic accuracy of digital mammography was nearly identical to that of film mammography, digital mammography achieved greater accuracy in women under 50 years of age, and also those with dense breast tissue.2
A major event for 2011 in the oncology arena was the Food and Drug Administration’s (FDA) approval of the Selenia Dimensions digital breast tomosynthesis system (Dimensions 3-D) from Hologic, Inc. The Selenia Dimensions system was the first such system to gain FDA approval.3,4 Breast tomosynthesis, or 3-D mammography, is a form of digital mammography in which breast images are taken at different angles and then digitally resynthesized and reproduced as 3-D images. In a screening mammogram, the presence of a tumor is signaled by mass, microcalcifications, or alterations in breast structure.5 Breast tomosynthesis has proven to be particularly useful for the imaging of the radiographically dense breast when these structures are difficult to visualize; the surrounding dense tissue may camouflage a cancerous lesion. Both digital mammography and breast tomosynthesis are useful in visualizing the radiologically dense breast. The potential advantages of breast tomosynthesis include better detection of cancer, fewer callbacks, and fewer false positives with less radiation exposure — less than 300millirads, well within FDA limits. Standard mammograms result in exposure of 150 to 200millirads.6