Breast screening
The vast majority of women who are screened will have reassuring results. However, women with increased breast density may need additional screening.
When breast tissue is dense, it appears white on a mammogram. Unfortunately, breast cancer also appears white, so in a traditional mammogram, trying to find a breast cancer can be like trying to find a snowflake in a snowstorm.
There are new and innovative ways to diagnose breast cancer than ever before.
- Conventional Mammography – We all know that mammography is still the best and first step in screening for breast cancer. Early detection means finding cancers early, which means higher cure rates. What surprises many women is that if something looks suspicious on a mammogram, we have more imaging options than ever before.
- 3-D Mammography known as Tomosynthesis – This screening technology, can help radiologists look at breast tissue via multiple thin layers without shadowing and distortions. This helps find suspicious areas that may be overlooked from conventional mammography.
- Whole Breast Ultrasound – An advanced screening tool that allows radiologists to look differently through dense breast tissue to screen for small breast cancers that might be obscured in a mammogram. I’ve had this procedure myself. It is painless, takes less than 10 minutes and continues to be a beneficial screening tool for women with dense breast tissue.
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Breast Ultrasound vs. Mammogram
The main differences between breast ultrasounds and mammograms are their roles in the breast cancer screening process. While each test is important in identifying possible cancer, they each have a different purpose.
Ultrasound or Mammogram?
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A mammogram is an X-ray of the breasts. Mammograms are the most effective breast cancer screening test. They can take multiple pictures of the breast and identify calcifications (calcium deposits within breast tissue). In addition, mammograms are important for diagnosing and following up after breast cancer. A breast ultrasound or sonogram is generally used for diagnostic reasons. For example, an ultrasound is most helpful when evaluating dense breasts or a suspicious lump found on a mammogram.
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A breast ultrasound is good at distinguishing a benign fluid-filled cyst from a solid mass. An ultrasound of the breast can help define a mass found by touch, even if it does not appear on a mammogram.
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A big difference between a mammogram and a breast ultrasound is how they work. Mammograms use low-dose radiation to X-ray the breasts, while ultrasounds use sound waves.
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Radiation: Although you will be exposed to small amounts of radiation during a mammogram, the benefits of having one usually outweigh the risks. However, if you're pregnant, radiation from a mammogram can harm the fetus.
Sound waves: The sound waves generated by an ultrasound create an echo that produces the ultrasound image. No radiation is emitted during a breast ultrasound. -
Are Breast Ultrasounds Better Than Mammograms?
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Mammograms: If a screening mammogram identifies a suspicious area in the breast, you will likely need a diagnostic mammogram. A diagnostic mammogram takes more pictures than a routine screening mammogram and focuses on the affected area.
Ultrasounds: A breast ultrasound cannot spot microcalcification in the breast. Although calcifications are not always a sure sign of breast cancer, many early breast cancers are suspected because calcifications are seen.
Recent studies suggest that people who have dense breasts could benefit from a mammogram plus fast breast magnetic resonance imaging (fast breast MRI). The combination of tests may produce fewer false positives than mammography and ultrasound alone. Ultrasounds are conducted using a handheld transducer that slides across the skin to look for an abnormality. That means that the whole breast cannot be looked at closely. Cannot examine deep breast tissue: An ultrasound helps providers see superficial lumps well, but a mammogram is better at looking for abnormalities that are deep in the breast tissue. Does not evaluate the axillary lymph nodes (armpits): Evaluation of the axillary lymph nodes (divided into three levels: the lower, middle, and upper part of the armpit) can help determine if breast cancer has travelled beyond the breast. When breast cancer is in the axillary lymph nodes, they become swollen and larger than normal. If breast cancer is found in the axillary lymph nodes it could mean the disease has metastasised (spread) to other parts of the body) -
That said, mammograms and ultrasounds are both subject to user error. One study found that radiologists missed 10% to 30% of breast cancers seen on mammograms. Additionally, the operator's skill level can significantly affect the accuracy of a breast ultrasound result.
If you are trying to decide whether a breast ultrasound or a mammogram is the right choice for you, here are a few things to consider:
- Risk factors: Having a family history of breast cancer or inherited genetic mutations like breast cancer gene 1 and breast cancer gene 2 (BRCA 1 and BRCA 2, respectively) put you at higher risk for developing breast cancer. You will likely need yearly mammograms before the age of 40.
- Breast density: Having dense breasts makes finding breast cancer more difficult and increases the risk of developing breast cancer. Having a mammogram, ultrasound, and possibly an MRI can improve the accuracy of breast cancer screening for people with dense breasts.10
- Age: People at average risk for breast cancer can begin yearly mammograms at the age of 40. At 55, mammograms can be spaced out every other year.11
- Palpable lump: There are times when an ultrasound is appropriate for breast cancer screening. When a palpable lump (one that can be felt by touch) exists but the mammogram is normal, ultrasound can be used to determine the likelihood of the lump being cancerous.
Breast MRI (Magnetic Resonance Imaging) – This diagnostic screening option is particularly helpful for women with a history of breast cancer, or those who have tested positive for the BRCA genetic mutations.An MRI is a powerful magnetic and radio waves to generate highly detailed images, especially of the soft tissue. Breast MRI might be best for young people with dense breasts who have significant risk factors for breast cancer.
Key Differences
The following table may help you understand the key differences between a mammogram and a breast ultrasound.
| Mammogram | Ultrasound |
| Uses a small amount of radiation | Does not use radiation |
| Can't tell the difference between a cyst and a solid mass | Can help distinguish between solid masses and cysts |
| Not as good at spotting abnormalities in people with dense breast tissue | Better at spotting abnormalities in people with dense breast tissue |
| Good at spotting calcifications | Much less effective at finding calcifications |
| Different views can give the radiologist a look at the entire breast | Cannot view the entire breast |
| Cannot view the entire breast | Cannot view deep breast tissue |
| Can be used to find suspicious areas deeper inside the breast | Cannot view the axillary lymph nodes |
| Can view the axillary lymph nodes | Typically used for diagnosing abnormalities found during screening |
Unfortunately, neither mammograms nor ultrasounds are 100% accurate. Knowing how your breasts normally look and feel and reporting any changes to your provider is the first—and most important—step in early detection.
