by Tracie Kong, MD and Laura Doepke, MD
The standard breast MRI acquisition technique should include the following sequences at minimum:
Additional sequences, depending on the indication, patient history, and institutional protocols may include:
Post-processing techniques may generate additional data, including:
The protocol may be adjusted for breast implants using silicone specific sequences to assess silicone implant integrity. The field of view should cover the entire bilateral breasts from the axillary tail to the inframmmary fold, while excluding the posterior thorax to optimize resolution. Ultrafast or abbreviated MRI techniques are also being studies and implemented to allow for high throughput screening and diagnostic imaging.
Interpreting a breast MRI involves distinguishing suspicious lesions from background parenchymal enhancement. Approaches vary and depend on the acquisition protocol and clinical context. The following is one suggested approach:
Figure 1: BI-RADS lexicon for the amount of fibroglandular tissue.
Figure 2: BI-RADS lexicon for the background parenchymal enhancement.
Each important finding should be described using the BI-RADS lexicon. Findings that demonstrate enhancement include foci, masses, and non-mass enhancement, which are detailed in separate articles. Other findings that may enhance include lymph nodes and skin lesions. Non-enhancing findings include cysts, post-operative collections, and foreign bodies that cause signal voids (Fig. 3). Benign lesions should be noted as such to avoid unnecessary intervention.
Figure 3: BI-RADS lexicon for examples of findings.
Associated features should also be discussed using the BI-RADS lexicon and used to form the final assessment. Associated features may include nipple retraction and/or invasion; skin retraction, thickening, or invasion; and pectoralis muscle and/or chest wall invasion (Fig. 4).
Figure 4: BI-RADS lexicon for examples of associated features.
The final assessment and management of a breast MRI examination should follow the BI-RADS categories, which are based on the BI-RADS categories developed for mammography (Table 1).
| Assessment | Management | Likelihood of Malignancy |
|---|---|---|
| Category 0: Incomplete – Need Additional Imaging Evaluation | Recommend additional imaging: mammogram or targeted US | N/A |
| Category 1: Negative | Routine breast MRI screening if cumulative lifetime risk ≥ 20-25% | Essentially 0% |
| Category 2: Benign | Routine breast MRI screening if cumulative lifetime risk ≥ 20-25% | Essentially 0% |
| Category 3: Probably Benign | Short-interval (6-month) follow-up | ≥ 0% but ≤ 2% |
| Category 4: Suspicious | Tissue diagnosis | > 2% but < 95% |
| Category 5: Highly Suggestive of Malignancy | Tissue diagnosis | ≥ 95% |
| Category 6: Known Biopsy-Proven Malignancy | Surgical excision when clinically appropriate | N/A |
