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What do breast MRI results mean, and should you be worried about BIRADS scores?
Most breast MRI BI-RADS scores are not cancer but guide follow-up. BI-RADS 3 and 4A often cause anxiety, but MRI can clarify these findings with high accuracy, helping many avoid unnecessary biopsies.
Instalab Research

If you’ve had a breast MRI and were told you have a BI-RADS score, it can be unsettling. You might be wondering whether this means you have cancer or if you need to panic. The good news is: in most cases, you don’t. BI-RADS is simply a standardized system that radiologists use to describe what they see on your imaging. It helps ensure consistent follow-up and decision-making, but it does not diagnose cancer on its own.

What Do BI-RADS Categories Mean?

  • BI-RADS 1 and 2: The scan is either completely normal or shows clearly benign (non-cancerous) findings. These are “no news is good news” categories. You just continue with regular screening.
  • BI-RADS 3: The finding is probably benign. There’s less than a 2% chance it’s cancer. Your doctor may recommend a short-term follow-up MRI in about 6 months to monitor any changes.
  • BI-RADS 4A: Low suspicion of cancer (2-10%). A biopsy may be suggested to confirm, but MRI often helps clarify whether the lesion is concerning.
  • BI-RADS 4B, 4C, or 5: These indicate increasing levels of concern. BI-RADS 4B and 4C suggest moderate to high suspicion (10-50% and 50-95%, respectively), while BI-RADS 5 means the radiologist sees a lesion highly suggestive of cancer (>95%). A biopsy is typically recommended.

What’s reassuring is that for both BI-RADS 3 and 4A, MRI has a very high negative predictive value—meaning if the MRI shows no sign of cancer, it’s almost always correct. That’s especially important because breast MRIs can detect subtle tissue changes that other imaging might miss or misclassify. When interpreted correctly, this can help avoid unnecessary biopsies, surgeries, and the emotional toll that comes with them.

When the score is BI-RADS 4B, 4C, or 5, the concern is higher. These scores suggest a more significant risk of cancer, ranging from 10% to over 95%, and biopsy is typically recommended. But even then, it’s important to remember that these are still probabilities, not diagnoses. Only a biopsy can confirm cancer.

Researchers have shown that using MRI as a second look for BI-RADS 3 or 4A findings significantly reduces the number of unnecessary biopsies. One study even found that the “Kaiser score,” which incorporates additional MRI features, can further improve decision-making for ambiguous lesions.

So if your MRI report includes a BI-RADS score and you’re feeling overwhelmed, take a moment. The majority of findings, even those flagged as uncertain, are not cancer. Breast MRI is a powerful tool, especially when used to clarify ambiguous cases, and it gives your doctor more confidence in choosing the safest, most appropriate next step.

References
  • Hernández, L., Díaz, G., Posada, C., & Llano-Sierra, A. (2021). Magnetic resonance imaging in diagnosis of indeterminate breast (BIRADS 3 & 4A) in a general population. Insights into Imaging, 12. https://doi.org/10.1186/s13244-021-01098-z.
  • Dorrius, M., Pijnappel, R., Sijens, P., Weide, M., & Oudkerk, M. (2012). The negative predictive value of breast Magnetic Resonance Imaging in noncalcified BIRADS 3 lesions.. European journal of radiology, 81 2, 209-13. https://doi.org/10.1016/j.ejrad.2010.12.046.
  • Milos, R., Pipan, F., Kalovidouri, A., Clauser, P., Kapetas, P., Bernathova, M., Helbich, T., & Baltzer, P. (2020). The Kaiser score reliably excludes malignancy in benign contrast-enhancing lesions classified as BI-RADS 4 on breast MRI high-risk screening exams. European Radiology, 30, 6052 - 6061. https://doi.org/10.1007/s00330-020-06945-z.
  • Balleyguier, C., Ayadi, S., Van Nguyen, K., Vanel, D., Dromain, C., & Sigal, R. (2007). BIRADS classification in mammography.. European journal of radiology, 61 2, 192-4. https://doi.org/10.1016/J.EJRAD.2006.08.033.
  • Guillaume, R., Taieb, S., Ceugnart, L., Deken-Delannoy, V., & Faye, N. (2016). BIRADS 3 MRI lesions: Was the initial score appropriate and what is the value of the blooming sign as an additional parameter to better characterize these lesions?. European journal of radiology, 85 2, 337-45. https://doi.org/10.1016/j.ejrad.2015.11.032.