What Is Tomosynthesis?
If you’re getting checked for breast cancer, you may have the option of digital tomosynthesis. Although it’s a long word (it’s pronounced toh-moh-SIN-thuh-sis), it’s a simple idea: Tomosynthesis is a kind of three-dimensional (3D) mammogram. It uses low-dose X-rays and a special computer program to create 3D images of your breasts.
Your doctor might call it digital breast tomosynthesis (DBT) or just a 3D mammogram.
Like regular mammograms, this exam can be used for screening — the regular tests you get when you have no symptoms, to pick up possible early signs of breast cancer. It also can be used as part of a diagnostic workup — the tests you get when you have symptoms, such as a lump or nipple discharge, or when earlier tests turn up something that needs a closer look.
Neither a regular mammogram nor a 3D mammogram can diagnose or rule out breast cancer by themselves. To do that, you need a biopsy, a procedure in which cells are taken from your breast and tested.
How It Differs From Regular Mammography
Regular mammograms take two X-ray images of each breast: top to bottom and a side-to-side view from an angle. The pictures it produces are two-dimensional, or 2D. As a result, overlapping breast tissue in these pictures can hide breast cancers or make a normal spot appear to be abnormal.
Tomosynthesis uses X-rays, too, but it takes more pictures from more angles. It produces the same 2D pictures as a regular mammogram but adds 3D images as well. A computer can put these images together so that a doctor can view your breast tissue slice by slice.
Because of these additional views, 3D mammograms can cut down on the need to come back for another mammogram, which can happen if your first test produces unclear results. They also appear to find more breast cancers than regular mammograms. But whether that makes a difference in your risk of eventually dying from breast cancer remains under study.
While 3D mammogram machines are approved by the FDA, they aren't available at all facilities that offer mammograms.
How Does Tomosynthesis Work?
Like regular mammograms, 3D mammograms take X-ray pictures of your breasts. Some kinds of tissue, including bone, solid tumors, and dense (less fatty) breast tissue, absorb more radiation from the X-rays, so they show up as white areas in the pictures.
But instead of aiming the X-rays at just two spots in each breast, the 3D machine uses an X-ray tube that moves in an arc over each breast, taking multiple images from different angles.
These images then go to a computer that can combine them into many 3D images showing segments, or slices, of your breast tissue. The machine also creates standard 2D images. That combination may make it easier for radiologists — the doctors who look at mammogram results — to clearly identify normal breast tissue and find potential tumors that might otherwise remain hidden, especially in dense breasts.
Both 2D and 3D mammograms are good screening tools for breast cancer. You should talk with your doctor about whether seeking out 3D screening makes sense for you.
What to Expect During Tomosynthesis
Tomosynthesis is done in the same radiology clinics where you get other mammograms. These can be in hospitals or freestanding imaging centers. If you're going to a place you've never used before, be sure to mention that when you make the appointment. The staff will ask you to bring or send any past mammogram results so they can be used for comparison.
Preparation for tomosynthesis is like getting ready for any mammogram. Don’t use deodorant, talc, oils, or lotions on your upper body before the exam, as these products might create white spots on your mammogram images. They also might make your breasts slippery and harder to place in the equipment.
You’ll also have to take off any clothing above your waist and put on a robe. So, you'll probably be more comfortable if you wear a two-piece outfit, with pants or a skirt, so you don't have to undress as much. And leave necklaces and dangly earrings at home so you don't have to remove and risk losing them.
During the exam, you’ll stand in front of a 3D mammography X-ray machine. The technologist will adjust the machine to your height and put your breast between two plates. The upper plate will move down to compress your breast so that it's flatter. That produces the best images.
The actual picture-taking lasts about 4 seconds, which is just a second or two longer than a standard mammogram. You'll be asked to stand still and hold your breath while the scan is done.
The technician will then release the compression and reposition your breast for a second set of images. If this is a screening mammogram, you'll repeat the process with the second breast. The technologist then might ask you to wait a few minutes while they check to see that the radiologist has the images needed. If you don't need any retakes or additional tests that day, the whole appointment should be over in about 30 minutes. Before you leave, be sure to ask when your results will be available.
Is Tomosynthesis Painful?
Tomosynthesis requires your breast to be compressed for just a second or two longer than a standard mammogram, so it should be no more painful. With that said, any mammogram can cause some discomfort. Your breasts are squeezed and you're standing in a somewhat awkward position — a combination that can be especially uncomfortable if you have sensitive breasts, chronic pain, physical disabilities, or a lot of anxiety about the test.
There are things you can do to reduce the discomfort.
First, if you have periods, your breasts may be less tender than usual in the week or two after your period ends, so that can be the best time to schedule any mammogram. It's also fine to take a painkiller such as ibuprofen or acetaminophen an hour before the exam if those drugs are safe for you. If you feel anxious, try listening to soothing music and taking deep breaths just before the test.
During the exam, don't hesitate to tell the technician if you are in pain. They might be able to use less compression, though it's important to use enough pressure to get good images.
How Much Does Tomosynthesis Cost?
Tomosynthesis costs more than a traditional mammogram due to the equipment required and the time involved in interpreting the results. In one study, average screening costs were about $60 higher.
But that doesn't mean you'll pay that amount. First, you should know that Medicare, Medicaid, and most private insurers cover the cost of regular 2D mammograms for breast cancer screening.
Medicare and Medicaid cover any additional fees that come with tomosynthesis. So do many private insurers. But you'll want to learn the details of your own coverage. For example, some private insurers that say they cover the 3D test may apply the charge to your deductible or may cover the standard mammogram amount but not the extra cost of the 3D imaging.
Another factor: Some states have laws that say clinics can't charge extra for 3D screening mammograms. In other states, laws require insurers to cover the full cost, just as they do for regular 2D mammograms.
If you are getting a mammogram to diagnose a breast problem, such as a lump, or follow up on an abnormal screening mammogram, insurers are less likely to cover the full cost.
If you don't have insurance, you should know that every state has a program that covers the cost of screening mammograms. Check with your state's health department for details, including whether you can get a 3D mammogram.
Benefits of Breast Tomosynthesis
While it's not yet clear that getting your screening mammograms with 3D imaging will change your chances of ever dying of breast cancer, studies find that some benefits are likely.
These include:
Fewer false alarms. The more detailed images do a better job of showing normal tissue that might look like a questionable spot on a regular mammogram. So, you're less likely to be called back for more testing and to endure the anxiety you might feel during the wait. Callbacks also can add to costs and inconvenience.
Finding slightly more cancers. Research shows that adding tomosynthesis detects about one more cancer per 1,000 women screened than a standard mammogram alone.
Better results for dense breasts. About half of women and people assigned female at birth have dense breasts, meaning greater areas of their breast tissue will show up as white areas on a standard mammogram image. Adding tomosynthesis produces images that make it easier to spot a cancer in the dense tissue.
Possible Risks of Breast Tomosynthesis
Getting a mammogram that produces 3D images is safe. But any medical procedure has risks. For this test, they include:
Low radiation exposure. You may get slightly more radiation or about the same as in a standard mammogram, depending on whether the machine used at your clinic creates 2D and 3D images separately or at the same time. In either case, this is considered a safe level of radiation.
False positives. That's what doctors call it when a test finds something that looks abnormal but turns out to be harmless. It can happen with any kind of mammogram. You might go through a lot of worry and need a biopsy or other testing before finding out everything is OK.
Missed cancers. Any mammogram can miss cancers that are small or otherwise hard to see. That's one reason health experts recommend regular screening mammograms, giving you more chances to catch a growing tumor. Recommendations vary but range from once a year to once every 2 years, usually starting at age 40 for women at average risk.
Tomosynthesis Results
After your test, a radiologist will look at the new 3D and 2D images, plus any past mammogram results, to find out if there's any cause for concern. At some clinics and in some situations, the radiologist might give you your results right away.
More typically, a report goes to your doctor within a few days and the doctor shares it with you through a phone call or a visit. Or you might just get the results through an online portal. If a doctor referred you for a mammogram, either for screening or diagnosis, be sure to ask how they'll share the results and speak up if you have any preferences.
Under federal law, the mammography center also has to send you written results, in plain language, within 30 days. In some situations, like when a likely cancer is found, they have to send you a letter within a week.
The report might tell you that the test found no signs of cancer. Or it might say you need more tests to check suspicious spots. Those might include another mammogram, an ultrasound, an MRI, or a biopsy. Only a biopsy can confirm cancer. But most follow-up tests end up finding no cancer.
Takeaways
Tomosynthesis is a mammogram that creates 3D images. It may find more cancers, especially in dense breasts, and cause fewer false alarms. You get it in the same way as any other mammogram. But it can cost a little more if your insurance doesn't fully cover it.
Tomosynthesis FAQs
Is tomosynthesis a CT scan?
No. Tomosynthesis uses low-dose X-rays, just like regular mammograms.
What is bilateral mammography with tomosynthesis?
You might see that written on a form from your doctor referring you for your 3D mammogram. Bilateral means both sides, so it just means you're getting a mammogram on both breasts that will include 3D imaging.
