From the Guidelines
For patients with dense breast tissue, supplemental screening with breast ultrasound or MRI is recommended in addition to standard mammography, with the choice of supplemental screening modality depending on the patient's overall breast cancer risk factors, preferences, and resource availability. Mammography alone has reduced sensitivity in dense breasts because both dense tissue and potential tumors appear white on mammograms, making cancer detection more difficult 1. Breast ultrasound is often the first supplemental test due to its wide availability, lack of radiation, and ability to detect small invasive cancers that may be obscured on mammography. Breast MRI offers the highest sensitivity for cancer detection but is typically reserved for high-risk patients due to cost and limited accessibility 1. Automated breast ultrasound (ABUS) and digital breast tomosynthesis (3D mammography) are newer technologies that may also improve cancer detection in dense breasts.
Some key points to consider when choosing a supplemental screening modality include:
- The patient's breast cancer risk factors, such as family history and genetic mutations
- The patient's preferences, such as concerns about radiation exposure or the desire for a more sensitive test
- The availability of resources, such as access to MRI or ultrasound facilities
- The potential benefits and limitations of each supplemental screening modality, such as the increased sensitivity of MRI but also its higher cost and limited accessibility 1.
The American College of Radiology recommends that patients with dense breast tissue discuss their individual risk factors and screening options with their healthcare provider to determine the most appropriate screening strategy 1. Ultimately, the goal of supplemental screening is to improve breast cancer detection and reduce morbidity and mortality, while also minimizing the risks and limitations of each screening modality.
From the Research
Recommended Imaging Modalities for Dense Breast Tissue
The following imaging modalities are recommended for patients with dense breast tissue:
- Digital breast tomosynthesis (DBT) is the preferred mammographic technique for producing a simultaneous reduction in recalls 2, 3
- Ultrasound (US) further increases cancer detection after DBT and reduces interval cancers, but it also produces substantial additional false-positive findings 2
- Molecular breast imaging (MBI) improves cancer detection with an effective radiation dose that is approximately fourfold that of DBT, but is still within accepted limits 2
- Magnetic Resonance Imaging (MRI) provides the greatest increase in cancer detection and reduces interval cancers and late-stage disease 2, 4
- Contrast-enhanced mammography (CEM) appears to offer performance similar to that of MRI, but further validation is needed 2, 5
Comparison of Imaging Modalities
The following comparisons can be made between the different imaging modalities:
- DBT has been shown to increase cancer detection rates and reduce recall rates compared to 2D digital mammography (DM) 3, 6
- CEM has been shown to have a higher mean glandular dose (MGD) per breast compared to FFDM or DBT alone, but a lower MGD compared to combined FFDM-DBT 5
- MRI has been shown to provide the greatest increase in cancer detection and reduce interval cancers and late-stage disease, but also increases false-positive recalls and biopsy recommendations 4
Considerations for Screening
The following considerations should be taken into account when screening for breast cancer in patients with dense breast tissue:
- The use of DBT and/or MRI may increase the detection of breast cancer, but also increases the risk of false-positive findings 2, 4
- The addition of supplemental MRI to DBT screening may lead to greater benefits, but also increased harms 4
- The balance of benefits and harms should be considered when deciding on a screening strategy for patients with dense breast tissue 4