Breast MRI Lexicon Overview — BI-RADS v2025
This page is the map-of-content for the BI-RADS v2025 Breast MRI Lexicon. All descriptor, finding, and technique pages are linked below.
Key v2025 Changes From 5th Edition
| Change | 5th Edition | v2025 |
|---|---|---|
| Mass shape — lobulated | Included in oval category | Reintroduced as separate shape descriptor |
| Margin descriptor | ”Irregular” | Replaced by “Indistinct” (avoids confusion with irregular shape) |
| Focus | Present in lexicon | Removed from lexicon |
| Rim enhancement | ”Rim enhancement” | Renamed “Thick rim enhancement” |
| Early post-contrast series naming | ”Initial” post-contrast | Renamed “Early” post-contrast |
Lexicon Structure
A. Breast Tissue
A. Amount of Fibroglandular Tissue (FGT)
- FGT — Almost Entirely Fatty
- FGT — Scattered Fibroglandular Tissue
- FGT — Heterogeneous Fibroglandular Tissue
- FGT — Extreme Fibroglandular Tissue
- Fibroglandular Tissue
B. Background Parenchymal Enhancement (BPE)
B. Findings
C. Masses
- Masses
- Shape: Mass Shape — Oval | Mass Shape — Lobulated | Mass Shape — Round | Mass Shape — Irregular
- Margin: Mass Margin — Circumscribed | Mass Margin — Indistinct | Mass Margin — Spiculated
- Internal Enhancement: Mass Enhancement — Homogeneous | Mass Enhancement — Dark Internal Septations | Mass Enhancement — Heterogeneous | Mass Enhancement — Thick Rim Enhancement
- T2 Signal: Mass T2 Signal — Hyperintense | Mass T2 Signal — Not Hyperintense
D. Non-Mass Enhancement (NME)
- Non-Mass Enhancement
- Distribution: NME Distribution — Diffuse | NME Distribution — Regional | NME Distribution — Focal | NME Distribution — Linear | NME Distribution — Segmental
- Internal Enhancement: NME Enhancement — Homogeneous | NME Enhancement — Heterogeneous | NME Enhancement — Clumped | NME Enhancement — Clustered Ring
E. Enhancement Kinetics
C. Technique Pages
Two Primary Finding Types
There are two primary enhancing breast MRI finding types: masses and non-mass enhancement (NME). To be significant, enhancing findings must be morphologically unique and distinct from BPE.
Board Pearl
Focus has been removed from the BI-RADS v2025 lexicon. Small dots of enhancement are most often benign and should be dismissed, or characterized as a small mass or focal NME using standard criteria.
Benign-Favoring Mass Features (Combined <2% Cancer Risk)
A mass with ALL of the following has a likelihood of cancer ≤ 2%:
- Oval shape
- Circumscribed margin
- Homogeneous internal enhancement OR dark internal septations
- T2 hyperintense signal
Board Pearl
T2 hyperintensity alone is insufficient. ALL four features must be present together to achieve <2% malignancy risk.