WILL DIGITAL BREAST TOMOSYNTHESIS EVENTUALLY REPLACE 2D MAMMOGRAPHY?
Breast cancer affects millions of women worldwide. Standard mammography is still considered the “gold standard” for breast cancer screening, digital mammography being the optimal choice, but it has several drawbacks. Digital breast tomosynthesis (DBT) is a new technology that offers patients and operators the perfect synthesis of comfort, design, accuracy and speed. What makes it special is the low radiation dose and ability to diagnose cancer in dense breasts and may be the perfect candidate to someday replace standard 2D mammography.
The latest breast cancer screening recommendations
The current recommendations of the American Cancer Society (ACS), from October 2015, suggest women at average risk get screened from age 40-44 by choice. Now, by ACS standards women from 45-54 are urged to get a yearly mammogram and those from 55 and over should get one every 2 years. Breast self-exams and clinical breast exams are no longer advocated by the ACS as they may bring about anxiety and false-positive results which may lead to unnecessary treatment and diagnostics. Women at high risk, like those with a personal or family history of breast cancer should get an MRI exam and a mammogram every year. Many women over 40 may start to worry about breast cancer, and as such, should consult with their healthcare provider about the risks and benefits of getting an annual mammogram.
The American Cancer Society takes into account evidence from hundreds of studies, compiles and analyzes this information and along with its own research adjusts or amends screening protocols.
The limitations of mammograms
For many years mammography was considered to be the most cost-effective, reliable and safe screening technique. Many women have heard of mammograms, but they may not know where mammograms fall short.
- Dense breasts (they can mask or camouflage a potential cancer causing either false-positive (FP) or false-negative (FN) results)
· Breast compression during exam (uncomfortable, and in some cases may cause overlapping of tissue, which can also cause FP and FN results)
· Limited perspective (standard mammography is usually done by taking pictures from 2 angles, top to bottom and side to side).
Digital mammography, which doesn’t require X-ray film, is a step up from screen-film mammography (SFM). Doctors can magnify, post-process, share, store and copy images in a convenient digital form. Studies have shown that full-field digital mammography (FFDM) is more sensitive than SFM for dense breasts, but still fails to find some cancer compared to DBT.
Why is DBT a better choice for breast cancer screening?
Digital breast tomosynthesis, also known as 3D mammography was approved by the FDA in 2011. The principle of DBT lies in its unique design and functionality. The system has a swinging X-ray tube that rotates in an arc, taking images in specific increments. The acquired images are then run through an algorithm and are presented on the radiologist’s computer screen in 3D one millimeter slices.
Researchers and clinicians have come to a unanimous conclusion that DBT is more sensitive than 2D mammography and has up to 30-40% lower recall rates (the need to perform follow-up procedures). Breast tissue that is dense and practically impenetrable to FFDM can be separated layer by layer for an in-depth, comprehensive view using DBT.
Standard mammography runs into a similar dead-end as early stargazers, because its limited perspective can make a dense breast look like a jumble of stars, with no possibility of separating them out, or diminishing their light.
Digital breast tomosynthesis takes multiple images from multiple angles and finds lesions where standard mammography can’t, by some estimates as much as 50% more. It also has comparable radiation dose to 2D mammo, so women don’t have to worry about increased exposure.
Is DBT available around the world?
We have already reviewed Planmed’s Clarity 3D system but there are systems available from brands like GE, Hologic, Siemens and others. Currently, there are relatively few healthcare facilities with DBT systems installed, but that will soon change. If you’re considering upgrading your 2D mammo to a 3D system, you can be assured that your institution, your patients and your loved ones will benefit from this state-of-the-art technology.
There’s still room to grow
DBT is a new technique, similar to how a CT scanner works, which snaps images from angles in an arc around the breast. Although still considered to be the go-to screening method, 2D mammo may soon end up on the sidelines as DBT starts to become accepted and more available. Team BiMedis believes that DBT has the potential to be named the “gold standard,” replacing 2D mammography.
Helvie MA. Digital Mammography Imaging: Breast Tomosynthesis and Advanced Applications. Radiologic clinics of North America. 2010;48(5):917-929. doi:10.1016/j.rcl.2010.06.009.
Roth, R. G., Maidment, A. D. A., Weinstein, S. P., Roth, S. O., & Conant, E. F. (2014). Digital Breast Tomosynthesis: Lessons Learned from Early Clinical Implementation. RadioGraphics, 34(4), E89-E102. doi: doi:10.1148/rg.344130087
American Cancer Society recommendations for early breast cancer detection in women without breast symptoms. (2015, October 20). Retrieved November 20, 2015, from http://www.cancer.org/cancer/breastcancer/moreinformation/breast