Authors: Kirsten Hodges, ASA and Jeffrey Doyle, ASA
WHAT IS A MAMMOGRAM?
A mammogram is a low-dose x-ray image used to screen for and diagnose breast cancer and other diseases and disorders of the breast. Mammography produces images of breast tissue to enable radiologists to search for abnormalities such as fibroids, cysts, tumors or microcalcifications. Mammograms are the primary screening method for detecting breast disease, as the images can often reveal irregularities in the breast tissue before any symptoms are noticeable. There are two types of mammograms: (i) screening, a preventative scan using a small number of images; and (ii) diagnostic, used to investigate known changes, symptomatic conditions or abnormal findings yielded via a screening mammogram.
HISTORY OF MAMMOGRAPHY
In 1913, a German surgeon named Dr. Albert Salomon, who had used radiological technology to assess mastectomy specimens, was the first to publish his thoughts on the concept of using radiographic technology to differentiate benign and malignant findings through correlative radiological, macro and microscopic anatomical studies. In the 1960s, researchers in New York launched a large-scale randomized trial of mammography screening as a tool to reduce breast cancer mortality rates. In the course of the study, which lasted for nearly two decades, diagnostic x-ray breast screenings were conducted on more than 60,000 women. The long-term results of the trial, published in 1982 in the Journal of the National Cancer Institute, were shocking; participants saw a 30 percent reduction in deaths from breast cancer when compared to the control group.
In the 1990s, the National Institutes of Health (NIH) and the U.S. Food and Drug Administration (FDA) began establishing regulations and guidelines pertaining to digital mammography, with Congress passing the Mammography Quality Standards Act (MQSA) in 1992. The MQSA sought to establish minimum quality and safety standards to ensure universal access to quality mammography, as breast cancer posed the most commonly diagnosed and second most lethal oncological threat to women’s health in America. In 2000, the FDA approved the first digital mammography unit, the GE Senographe 2000D. Eleven years later, Hologic introduced the Selenia Dimensions, the world’s first three-dimensional (3D) digital breast tomosynthesis (DBT) machine. DBT is an advanced form of 3D imaging which uses twodimensional (2D) images from multiple angles to build a stacked 3D image. With a 40 percent higher detection rate, 3D tomography units quickly became the preferred option in women’s health clinics around the world.
SPECIALIZED TECHNOLOGY
Approximately 50 percent of women over 40 years of age have dense breast tissue, which reduces accurate detection rates of breast cancer on mammograms. Dense breast tissue has also been shown to increase the risk of developing breast cancer. Given these challenges, unique variations of the traditional mammography system have been developed in hopes of more timely diagnosis and greater accuracy in cancer detection rates among women with dense breast tissue.
Molecular breast imaging (MBI) takes an alternative approach to imaging breasts in comparison to traditional 3D mammography. MBI uses a specialized gamma camera to examine high risk patients with dense breast tissue in cases where a mammogram may leave a tumor undetected. One disadvantage of MBI is the higher dose of radiation exposure for patients, so MBIs are generally only performed when a mammogram may prove ineffective.
Breast specific gamma imaging (BSGI) is a similar procedure to MBI, but with the added requirement of intravenous radioactive injections to develop the nuclear image. This technology involves even higher radiation exposure risks than MBI; therefore, BSGI is typically only used when mammography or magnetic resonance imaging (MRI) systems cannot confirm a diagnosis. Due to the heightened exposure risk, BSGI is not used for routine screenings and, when supplemental screenings are needed for dense breast tissue scans, MBI is preferred over BSGI.
APPRAISAL CONSIDERATIONS
Normal Useful Life (NUL) – The NUL for a mammography system in a cost approach appraisal is estimated to be 7 to 10 years, with x-ray tube replacement expected by year 7. These estimates are largely based on usage volume and, more importantly, presuppose routine maintenance of the system.
CONCLUSION
In recent decades, mammography systems have significantly reduced breast cancer related deaths in women around the world. Proficiency surrounding the technology, various features and capabilities of mammography equipment is necessary when appraising these diagnostic imaging machines. As the value of a mammography system can be significantly affected by the unique characteristics and conditions discussed above, it is of the utmost importance to hire a qualified healthcare valuation firm, such as HealthCare Appraisers, to competently and reliably appraise mammography systems.
Read the other articles in our Insights on Imaging series: