Breast cancer remains one of the leading causes of cancer-related deaths in women worldwide. For decades, mammography has been the primary screening tool, helping to detect abnormalities before symptoms appear.
Studies suggest that regular mammograms have contributed to a significant reduction in breast cancer deaths (approximately 30 %), making them essential in early detection.1
However, mammography has its limitations. In individuals with dense breast tissue, detection is more challenging. To improve accuracy, tomosynthesis—also known as 3D mammography—was introduced.1 But how does it differ from traditional mammography, and does it offer a clear advantage?
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What is Mammography?
Mammography is a 2D X-ray imaging technique used to screen for breast cancer and detect abnormalities at an early stage. By capturing images of the breast with low-dose X-rays, it allows radiologists to identify signs of cancer that may not yet be palpable.2
How it Works
During a mammogram, the breast is positioned on a flat plate and gently compressed with a paddle to spread the tissue evenly. A low-dose X-ray passes through the breast to a detector on the other side, which captures the image.
In traditional film mammography, the image is developed on photographic film. In digital mammography, solid-state detectors convert X-rays into electronic signals, creating images that can be enhanced and analyzed on a computer.2
Digital mammography offers several advantages. It allows for adjustable contrast, making it easier to analyze dense breast tissue. It also enables computer-aided detection, which can highlight areas of concern for further review.
Additionally, because digital images can be stored and shared electronically, radiologists can compare them with previous mammograms to track changes over time.
On a mammogram, fat appears darker, while dense tissues such as glands, tumors, or calcifications appear whiter. This contrast helps radiologists identify potential abnormalities.
However, in individuals with dense breast tissue, the white areas can overlap, making it harder to distinguish normal structures from potential tumors.2 This is where tomosynthesis offers an advantage.
What is Tomosynthesis?
Tomosynthesis, also called 3D mammography, is a more advanced imaging technique that captures multiple X-ray images from different angles to create a layered, more detailed view of the breast.
The U.S. Food and Drug Administration (FDA) has approved tomosynthesis for breast cancer screening, and research suggests it may improve cancer detection while reducing false positives.3
A key study, the Oslo Tomosynthesis Screening Trial, analyzed over 12,000 screenings and found that tomosynthesis increased cancer detection rates from 6.1 to 8.0 cases per 1,000 screenings. It also helped lower false-positive rates from 10.3 % to 8.5 %, reducing unnecessary follow-ups and patient anxiety.4,5
How it works
During tomosynthesis, the breast is positioned similarly to a traditional mammogram, but instead of taking a single image, the X-ray tube moves in an arc (typically 15 to 60 degrees), capturing multiple low-dose images from different angles. These images are then reconstructed into thin, 1-mm slices using advanced software, allowing radiologists to examine the breast layer by layer. This reduces the issue of overlapping tissues, making it easier to detect abnormalities.3
By providing a 3D-like reconstruction, tomosynthesis helps distinguish between true masses and benign overlapping tissue, improving accuracy. However, one drawback is that microcalcifications, which can be early signs of cancer, may be less visible due to the wider sweep angle.
While the radiation dose remains within safe limits, tomosynthesis often involves slightly higher exposure than a standard 2D mammogram, especially when both methods are used together.3
Early research indicates that tomosynthesis enhances cancer detection, but larger studies are still underway to assess its overall effectiveness in reducing false positives and identifying early-stage cancers across different patient groups.3,6
Further studies will help determine whether tomosynthesis could eventually replace traditional mammography or if a combination of both provides the greatest benefit.
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Key Differences Between Tomosynthesis and Mammography
| Feature |
Mammography (2D) |
Tomosynthesis (3D) |
| Image Type |
2D X-ray images |
3D-like images with multiple angles |
| Detection Accuracy |
Effective but may miss small tumors in dense breasts |
Higher accuracy, better visualization of abnormalities |
| Radiation Exposure |
Lower dose |
Slightly higher but within safe limits |
| Screening vs. Diagnosis |
Standard for routine breast cancer screening |
Often used for follow-ups or high-risk patients |
Which One is Better?
The choice between mammography and tomosynthesis depends on individual needs and risk factors.
For General Screening
Mammography remains the most widely used screening method due to its availability, lower cost, and long-established role in reducing breast cancer mortality. It is particularly effective for detecting calcifications, which can be an early sign of ductal carcinoma in situ (DCIS), a common precursor to invasive breast cancer.
Additionally, because long-term data on mammography exist, it remains the preferred method for large-scale screening programs, allowing for standardized comparisons over time.
However, mammography may be less effective when analyzing dense breast tissue.7 To address this, some regions now require breast density notifications, informing individuals if additional imaging may be beneficial.
While mammography remains effective for most women, those with higher risk factors may benefit from more advanced imaging techniques.
For Higher Accuracy
Tomosynthesis offers enhanced imaging capabilities, making it particularly useful for high-risk patients, including individuals with dense breasts, a family history of breast cancer, or known genetic mutations such as BRCA1 and BRCA2. By reducing tissue overlap, tomosynthesis provides a clearer view of overlapping structures, lowering the chances of missing small tumors.
Since breast density affects cancer detection across different age groups, research continues to refine screening guidelines. Some studies suggest younger women, who typically have denser breast tissue, may benefit from tomosynthesis for earlier cancer detection, though further research is needed.
At the same time, a study by SM Ha and JM Chang found that women aged 60–70 with dense breasts had higher detection rates of early-stage cancers with tomosynthesis, emphasizing the need for age- and density-specific screening approaches.8
Additionally, research indicates tomosynthesis may improve the detection of aggressive, fast-growing cancers (grades 2 and 3), which are more likely to impact survival rates.8 It has also shown promise in tracking tumor response to treatment, helping radiologists assess changes in tumor size over time.
A Combined Approach?
Mammography remains the primary screening tool. However, tomosynthesis has demonstrated greater accuracy, particularly for those with dense breasts or higher risk factors. As screening guidelines evolve, tomosynthesis is being increasingly incorporated into breast imaging, especially for follow-ups and high-risk patients.
Research suggests that combining the two methods may provide the best results. The TOSYMA trial found that combining tomosynthesis with mammography significantly increases cancer detection rates, particularly for invasive cancers, compared to using mammography alone.9
At the same time, advancements in AI and automated image interpretation continue to refine both technologies, improving efficiency, accuracy, and accessibility.10
What's The Difference Between a 2D and 3D (Tomosynthesis) Mammogram? | Mercy Radiology
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References and Further Readings
1. Abdul Halim, A. A.; Andrew, A. M.; Mohd Yasin, M. N.; Abd Rahman, M. A.; Jusoh, M.; Veeraperumal, V.; Rahim, H. A.; Illahi, U.; Abdul Karim, M. K.; Scavino, E., Existing and Emerging Breast Cancer Detection Technologies and Its Challenges: A Review. Applied Sciences 2021, 11, 10753.
2. Nicosia, L., et al., History of Mammography: Analysis of Breast Imaging Diagnostic Achievements over the Last Century. Healthcare 2023, 11, 1596.
3. Dhamija, E.; Gulati, M.; Deo, S.; Gogia, A.; Hari, S., Digital Breast Tomosynthesis: An Overview. Indian Journal of Surgical Oncology 2021, 12, 315-329.
4. Skaane, P.; Bandos, A. I.; Gullien, R.; Eben, E. B.; Ekseth, U.; Haakenaasen, U.; Izadi, M.; Jebsen, I. N.; Jahr, G.; Krager, M., Prospective Trial Comparing Full-Field Digital Mammography (Ffdm) Versus Combined Ffdm and Tomosynthesis in a Population-Based Screening Programme Using Independent Double Reading with Arbitration. European radiology 2013, 23, 2061-2071.
5. Skaane, P.; Bandos, A. I.; Gullien, R.; Eben, E. B.; Ekseth, U.; Haakenaasen, U.; Izadi, M.; Jebsen, I. N.; Jahr, G.; Krager, M., Comparison of Digital Mammography Alone and Digital Mammography Plus Tomosynthesis in a Population-Based Screening Program. Radiology 2013, 267, 47-56.
6. Alshawwa, I. A.; El-Mashharawi, H. Q.; Salman, F. M.; Al-Qumboz, M. N. A.; Abunasser, B. S.; Abu-Naser, S. S., Advancements in Early Detection of Breast Cancer: Innovations and Future Directions. 2024.
7. Khanani, S.; Hruska, C.; Lazar, A.; Hoernig, M.; Hebecker, A.; Obuchowski, N., Performance of Wide-Angle Tomosynthesis with Synthetic Mammography in Comparison to Full Field Digital Mammography. Academic radiology 2023, 30, 3-13.
8. Ha, S. M.; Chang, J. M., Breast Cancer Detection: Digital Breast Tomosynthesis with Synthesized Mammography Versus Digital Mammography. Radiological Society of North America: 2023; Vol. 309, p e232911.
9. Weigel, S.; Heindel, W.; Decker, T.; Weyer-Elberich, V.; Kerschke, L.; Gerß, J.; Hense, H.-W.; Group, T. S. T. S., Digital Breast Tomosynthesis Versus Digital Mammography for Detection of Early-Stage Cancers Stratified by Grade: A Tosyma Subanalysis. Radiology 2023, 309, e231533.
10. Sechopoulos, I.; Teuwen, J.; Mann, R., Artificial Intelligence for Breast Cancer Detection in Mammography and Digital Breast Tomosynthesis: State of the Art. Seminars in Cancer Biology 2021, 72, 214-225.
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