BI-RADS Version 2025 Ultrasound Part 2
Review of high-yield concepts and updates from the BIRADS version 2025 atlas for breast ultrasound. Download the free study guide and check out the discount code section where you can currently get a 20% off discount for many BoardVitals subscriptions (subject to change). Prepare to succeed!
Part 2: The Ultrasound Lexicon
What are the 3 tissue composition patterns that exist in the BIRADS v2025 Lexicon?
1. Homogeneous Background Echotexture—Fat
2. Homogeneous Background Echotexture—Fibroglandular
3. Heterogeneous Background Echotexture
What are key characteristics for Homogeneous Background Echotexture—Fat?
This tissue pattern is composed mainly of fat lobules and echogenic bands of supporting structures.
What are key characteristics for Homogeneous Background Echotexture—Fibroglandular?
This tissue pattern is composed of a thick zone of homogenously echogenic fibroglandular parenchyma located under a layer of isoechoic subcutaneous fat. (Remember fat echogenicity is the definition or benchmark for “isoechoic” for breast ultrasound). So, subcutaneous fat on top and uniform fibroglandular tissue beneath the fat. Note that the subcutaneous fat layer is allowed to be extremely thin while still using this tissue pattern in a report.
What are key characteristics for Heterogeneous Background Echotexture?
With this tissue pattern there can be diffuse or focal heterogeneity of “areas of relative increased and decreased echogenicity”. It is stated that this pattern is more common with younger patients and is essentially the ultrasound equivalent of heterogeneously dense breast tissue on mammography. This pattern can be challenging, tends to have shadowing which can be artifactual due to the varied interfaces of fat and fibroglandular tissue, and requires special attention to optimize one’s ultrasound technique to try to improve imaging and remove artifactual shadowing form the image. The atlas suggests this tissue pattern may have a lower sensitivity for cancer detection of small and subtle lesions, but further research is necessary to better characterize any drop in cancer detection sensitivity with this tissue pattern.
True or false? Breast parenchymal echotexture pattern and qualitative assessment of glandular elements may be reported on screening ultrasound to recognize the impact of these variables on breast cancer risk and impact on interpretation.
True. While breast density reporting on mammography is mandated, to my knowledge this reporting is still optional on ultrasound. But it is interesting that BI-RADS indicates this may be helpful, and this can be reported now based on available evidence. Note that what we are talking about here is not the total amount of what is dense breast tissue on mammography, but rather whether that mammographic dense breast tissue is predominantly made up of glandular vs stromal elements—something that cannot be assessed by mammography but can be assessed on ultrasound. The glandular components will be relatively hypoechoic which are the terminal ductal lobular units (TDLUs) and the stromal elements will be relatively hyperechoic which is the fibrous tissue. Note that on mammography both the stromal and glandular components are dense and you cannot tell these apart mammographically.
What are the options for glandular tissue component that can be reported per the new BI-RADS atlas?
Glandular Tissue Component: Minimal (<25% of tissue in the fibroglandular zone comprised of TDLUs), Glandular Tissue Component: Mild (25-50% TDLUs), Glandular Tissue Component: Moderate (50-75% TDLUs) and Glandular Tissue Component: Marked (>75% TDLUs). The images in the BI-RADS atlas are helpful here. However, noting that many of you likely do not have access to the newest BI-RADS atlas due to the exorbitant price, I’ll try to explain what each of these categories looks like in words: Basically, look at the non-fatty glandular elements in the breast. If they are uniformly bright, that is suggesting a minimal glandular tissue component as the stromal elements are bright. If it is 50% bright and 50% dark you are in the moderate range. If it is mostly composed of hypoechoic tissue (frequently more hypoechoic than the fat, but not mass-like) with minimal bright elements intermixed, you are in the marked range.
What is the definition of a mass per the 2025 BI-RADS atlas?
A mass is a 3D space-occupying lesion visible in at least 2 different planes (if 3D volumetric imaging is performed you would see it in all 3 planes).
What are the 2025 BI-RADS descriptors for the shape of a mass on ultrasound?
Oval, lobulated (generally oval in shape but one or more indentations causing an undulating contour), round (AP, longitudinal, and transverse diameters all basically equal), and irregular (typically has angular protrusions and is not oval, lobulated, or round).
What are the 2025 BI-RADS descriptors for orientation of a mass on ultrasound?
Parallel (horizontal dimension greater than AP dimension) and non-parallel (AP>horizontal dimension). Parallel masses are wider than tall, non-parallel masses are taller than wide.
What are the 2025 BI-RADS descriptors for mass margins on ultrasound?
Circumscribed and non-circumscribed. Non-circumscribed is divided into indistinct (poorly defined or fuzzy margins), microlobulated (short cycle 2-3 mm ripples or undulations or microlobulations vs the macrolobulations that would define a lobulated shape), angular (sharp corners present), and spiculated (sharp radiating lines from the mass).
What are the 2025 BI-RADS descriptors for echo pattern of masses on ultrasound?
Anechoic (entirely black, no internal echoes), hypoechoic (relative to fat, but not anechoic), and hyperechoic (relative to fat, often equal to fibroglandular tissue) and isoechoic (equal to subcutaneous fat), heterogeneous (mixed echo patterns), and mixed solid and cystic (previously termed complex cystic and solid). Mixed solid and cystic masses are suspicious and require biopsy of the solid component to determine the cause of the mass (do not biopsy cystic components only). Remember that fat on breast ultrasound is dark compared to fibroglandular tissue, unlike the echogenic appearing fat in other body regions on ultrasound.
Many lipomas will be isoechoic and can be hard to see on both mammography (also fat density) and ultrasound as they blend with the subcutaneous fat in the breast. Therefore, if you are shown a mammogram and/or ultrasound image on a board exam, and it looks completely normal on first glance, one thing to consider is a lipoma--look for subtle margins around fat to suggest a lipoma.
The most classic mixed solid and cystic breast malignancy on board exams is likely a cystic papillary carcinoma so keep that entity in mind when shown a mixed solid and cystic breast mass on a breast ultrasound question.
What are the descriptors in the 2025 BI-RADS atlas for posterior features of a mass on ultrasound?
“No posterior features” is a descriptor meaning no shadowing or enhancement is present. Enhancement meaning there is an echogenic column deep to the mass, brighter than the tissue adjacent to the mass at the same depth. Basically, the tissue is brighter deep the mass than it is on the sides of the mass. Shadowing, meaning the tissue deep to the mass is darker than the tissue on the sides of the mass. Some cancers can present with shadowing as the only ultrasound finding present (on board exams think lobular breast cancer first). The descriptor combined has been removed because what really mattered with the combined descriptor was the shadowing, so if any shadowing is present behind a mass, this would simply now be described as shadowing, even if it is seen in combination with other posterior features. Note, however that this does NOT apply to edge shadowing, with a thin line of shadowing only behind the lateral edges of a curved mass which is a known ultrasound artifact.
True or false? Compound imaging on ultrasound reduces the conspicuity of posterior features.
True.
True or false? Posterior acoustic enhancement is a favorable prognostic feature of breast malignancies.
False. If a cancer shows posterior acoustic enhancement this likely means you are looking at a high-grade cancer. Therefore, posterior enhancement of a solid mass is concerning and not reassuring.
True or false? Microlobulated margins are descriptors in 2025 BI-RADS for both mammography and ultrasound masses.
False. Microlobulated margins were dropped from the mammography section but retained for the ultrasound section.
True or false? Any mass with an echogenic halo is automatically assigned indistinct margins.
True, per the specific description of this fact in the 2025 atlas.
True or false? Hyperechoic masses are always benign.
False. While top considerations for most hyperechoic masses are benign, and include lipomas, fat necrosis and hemangiomas, being hyperechoic does not independently confirm that the mass is benign. To be assessed as BI-RADS 2 benign, a hyperechoic mass must also be located in the subcutaneous fat, be uniformly hyperechoic with no hypoechoic or anechoic portions, must be oval in shape, must have circumscribed margins, must be parallel in orientation, and must have no posterior shadowing.
True or false? A hyperechoic mass clearly associated with a fat-containing mass on mammography is presumed benign.
True.
True or false? A hyperechoic mass associated with a soft tissue density mass on mammography is suspicious.
True. Although many of these will end up being benign on biopsy, some breast malignancies can present in this manner, with a few examples of hyperechoic breast cancers shown in the 2025 BI-RADS atlas.
True or false? A heterogeneous echo pattern within a mass strongly suggests malignancy.
False. Per the 2025 atlas, a heterogeneous echo pattern has little prognostic value in determining benign from malignant masses and be observed in fibroadenomas as well as breast malignancy.