BI-RADS Version 2025 Ultrasound Part 1
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 Board Vitals subscriptions (subject to change). Prepare to succeed!
Part 1: Ultrasound Image Quality
True or false? Breast composition reporting on ultrasound is now included in the newest BI-RADS v2025 atlas.
True. The atlas states that research is showing ultrasound assessment of breast density may indicate breast cancer risk and alter detection of findings on ultrasound. Specifically, the atlas states that the echotexture pattern and the glandular tissue content is important to assess risk and may impact the detection and characterization of breast cancer.
Anatomy is described in the ultrasound section of the BI-RADS atlas. What is the portion of the breast that classically gives rise to common malignant and benign pathologies?
This is a high-yield knowledge question for board exams. The terminal duct lobular units, commonly abbreviated TDLU, is the most peripheral aspect of the ductal system in which intra-lobular terminal ducts end in terminal duct lobular units. This is the tissue in the breast that gives rise to common benign and malignant pathologies in the breast.
True or false? The female breast at the beginning of puberty resembles the appearance of gynecomastia in a male on mammography and ultrasound.
True. The breast bud starts out as retroareolar hypoechoic tissue just posterior to the nipple. Patients of this age typically would not have a mammogram, so it is important to recognize the normal breast bud on ultrasound, which will look like benign gynecomastia, even though it is not gynecomastia, often comprising hypoechoic retroareolar flame-shaped glandular tissue extending from the nipple posteriorly. It is vital to recognize this as normal, so as not to biopsy or surgically remove or damage the breast bud which will harm or prevent normal breast development.
What is a cutoff for normal skin thickness of the breast on ultrasound?
The skin of the breast normally measures up to 2 mm in thickness except for the skin near the areolar region and inframammary fold where the skin is normally slightly thicker with no definite cutoff, though should be symmetric if abnormal skin thickness is in question.
What are the layers of the breast from superficial to deep on ultrasound, and what is the echogenicity of each layer?
From superficial to deep, the normal layers of the breast on ultrasound with corresponding echogenicity are:
-Echogenic skin
-Isoechoic subcutaneous fat including cooper’s ligaments
-Echogenic fibroglandular zone
-Isoechoic retroglandular fat
What scanning factors can make a vascular mass appear avascular on ultrasound?
Too much compression and/or incorrect Doppler settings can make a vascular mass appear avascular. Note that a primary challenge may be differentiating vascularity in a mass that appears anechoic or near anechoic for which a complicated cyst is more common, but a high-grade often triple negative breast cancer can appear similarly. If internal vascularity is seen this can be critical to determine need for biopsy for high-grade triple negative breast cancers which can nearly mimic a simple or complicated cyst if settings and technique are not optimized.
How does ultrasound transducer frequency simultaneously affect image contrast, spatial resolution, and beam penetration?
As frequency increases, image contrast increases, spatial resolution increases, and beam penetration decreases.
If you are trying to improve images of a mass located deep within a large breast, what are two simple things with your technique to optimize?
First, increase the compression placed on the breast by the ultrasound probe over the mass. This reduces the thickness of the breast at that location and thereby lowers beam attenuation. Second, consider using a lower frequency transducer. However, one must remember that increased compression may also reduce detection of any blood flow within the mass, so when evaluating with Doppler, scanning with less compression may be helpful.
What is the ideal field of view of the breast on ultrasound?
For general scanning, the optimal field of view extends from the skin to the pectoralis major but would not include the pleura or lung. If imaging small structures, zoom may be needed, but remember that the more you zoom, the lower the resolution may be and margins may appear more indistinct. If the field of view is too deep, superficial or small lesions may be suboptimally evaluated.
What is a simple display setting that can be utilized to evaluate lesions that are longer than a standard rectangular field of view?
Switch to a trapezoidal field of view. This offers a wider span of imaging and can be helpful for imaging larger findings, especially if deeper in the breast. Split-screen or panoramic imaging can also be helpful to image lesions that are larger than a trapezoidal field of view.
True or false? Volumetric ultrasound acquisitions allow 3D reconstructions of the breast, in addition to imaging in axial, sagittal, and coronal planes?
The answer is true. Volumetric (3D) imaging is most used with automated breast ultrasound systems. According to the BI-RADS v2025 atlas volumetric imaging with automated breast ultrasound systems can also reduce shadowing behind the nipple which is very common with handheld ultrasound.
When evaluating a lesion, what is the ideal focal zone placement?
Typically, one would want the focal zone to be positioned at the center of the lesion for ideal imaging. An acceptable focal one is located at the anterior to middle third of a lesion or region of interest. Many modern systems use multiple focal zones. However, if a targeted scan is being done with a single or narrow focal zone range, imaging with the focus in the midlevel of a mass is often ideal.
What is the purpose of gray scale gain with breast ultrasound?
Grayscale gain compensates for beam attenuation in deeper tissue. Like attenuation correction in PET imaging, superficial structures will have more beam available and deeper structures will have the beam more attenuated. Grayscale gain is intended to even out this attenuation difference, by boosting the deeper tissues echogenicity. For reference for how to set the grayscale, subcutaneous fat should appear medium gray and not black throughout the image regardless of depth. If gain is too high, tissue will be white or very bright which can obscure lesions. If grayscale gain is too low, solid lesions can appear anechoic and cystic.
What is the purpose of compound imaging in breast ultrasound?
Compound imaging utilizes multiple ultrasound beams sent out at slightly different angles and averages the information received into a single image. This reduces imaging noise and can improve imaging quality including assessment of mass margins and reduce imaging artifacts such as speckle artifacts. A potential downside of compound imaging is that posterior acoustic features can be less well evaluated such as posterior acoustic enhancement or shadowing. Often, compound imaging may make posterior enhancement or shadowing conical or triangular rather than rectangular or column-like when imaging without compound imaging.
What labels should be included on breast ultrasound images per BI-RADS v2025?
Breast ultrasound images should include the following labels: Facility name and location, exam date, patient first and last name, patient medical record number and/or date of birth, designation of whether imaging was of the left or right breast, clock-face notation to the nearest hour of the anatomic location or a labeled diagram of the breast showing the location of imaging, transducer orientation such as radial or anti-radial, distance from the nipple to the center of abnormality or area being scanned in centimeters, measuring from the nipple not the edge of the areola. Similar to mammography, centimeters from the nipple should be reported to the nearest whole centimeter “to avoid a misleading sense of precision”. The images should also include the sonographer and/or physician identification whether ID number, initial, or identifying symbol.
When measuring the size of a finding, reporting size to one decimal place when using centimeters or whole numbers when using millimeters is recommended (0.1 cm or 1 mm; not 0.11 cm and not 1.1 mm). Ideally measurement would include the longest axis measurement of the lesion and the short axis measurement perpendicular to the longest axis measurement. Additionally, a third measurement orthogonal to the first measurements would be provided to report the plane not yet measured.
True or false? When measuring a hypoechoic mass with an echogenic rind, the measurements should include the hypoechoic portion only and not the surrounding echogenic rind.
False. Measuring the hypoechoic portion and surrounding echogenic rind should be performed as this is more predictive of the true size of the process such as malignancy at pathologic evaluation. However, one must be careful to not include measuring the so-called pseudocapsule as part of a lesion which is simply the normal adjacent compressed tissue around a benign mass such as a fibroadenoma which can present with a thin echogenic rim.
True or false? When multiple cysts are present, every cyst must be measured in two planes.
False. Typically measuring the largest cyst in each breast along only its longest axis is sufficient, and images without measurements of other cysts could be obtained to document representative portions of the breast, as needed. However, if the cyst corresponds to an area of clinical concern or corresponds to a specific finding on mammography (or likely MRI though not specified) measurements should be recorded in 3 dimensions. If a cyst is incidentally seen, the long-axis only measurement is sufficient, and not all cysts need to be documented or reported.
Similar rules also apply to normal appearing intramammary lymph nodes. If the lymph node corresponds to a finding questioned on mammography or clinical assessment, these should be imaged and measured. If incidental, these do not necessarily require documentation.
True or false? A cyst in the axillary region is common.
False. The BI-RADS atlas states that while cysts can occur in the axillary tail or axilla, such a location should suggest other etiologies to include metastatic lymph nodes which can sometimes appear cystic. Using other information such as Doppler or elastography evaluation can be helpful in such settings.
True or false? Bilateral solid circumscribed masses may be considered benign, category 2, as with mammography with bilateral circumscribed, similar-appearing masses, if all appear similar and typically benign in appearance.
True. Per BI-RADS v2025 multiple bilateral solid circumscribed masses that all appear similar and typically benign in appearance may be considered benign and assessed as BI-RADS category 2. The atlas further states that if the interpreting physician wants to document all masses, each should be reported in a list with clock-face location, distance from the nipple, and measured in three orthogonal planes. However, the largest in each quadrant or breast could also be reported, per my understanding and reading of the language in BI-RADS v2025. The actual language states “If the interpreting physician prefers to document all masses rather than just the largest in each quadrant or in each breast, reporting should be in the form of a list including….”. However, per my understanding of this section, a typically benign appearance would not include any mass which has shown to significantly increase in size in comparison to prior imaging.
According to BI-RADS v2025 when may ultrasound be considered for supplemental screening in addition to mammography?
Screening breast ultrasound can be considered for women with heterogeneously or extremely dense breast tissue, or those at a high lifetime risk of 20% or greater of developing breast cancer, who are not candidates for breast MRI or women at high lifetime risk who cannot easily access breast MRI.
If performing screening breast ultrasound with a hand-held ultrasound system, what imaging documentation must be included?
For screening purposes, ultrasound images require a minimum of one image from each quadrant, and one image behind the nipple of each breast being screened. Automated breast ultrasound systems store images of the entire breast for later interpretation. When screening with hand-held systems, imaging can be performed by either the radiologist or sonographer given data showing similar outcomes between screening breast ultrasound performed by a physician or technologist.
If a suspicious or indeterminate finding is seen on a screening breast ultrasound study, what BI-RADS assessment category should be assigned?
Like screening mammography, a BI-RADS assessment category 0 should be assigned for any suspicious or indeterminate finding on screening breast ultrasound that requires further diagnostic workup. If a subsequent ultrasound is performed, this would be considered a separate diagnostic ultrasound, and both exams require separate final assessment codes for auditing purposes per the v2025 BI-RADS atlas. However, the interpreting radiologist may choose to dictate each exam in one report and provide an overall final recommendation, but the report should indicate separate BI-RADS assessment categories for the screening and diagnostic ultrasound evaluation.
Like screening mammography, screening breast ultrasound should only have BI-RADS assessment categories 0, 1, or 2 assigned. Like diagnostic mammography, assessment categories 3, 4, or 5 should be assigned only following diagnostic imaging evaluation.
Some of you might wonder: if we see a suspicious mass on a breast ultrasound, why can’t we just assign it a BI-RADS 4 and go straight to an ultrasound-guided biopsy?
While the image quality section of the BI-RADS atlas doesn't explicitly spell this out, my own thoughts are that there are several important steps that need to happen first. Before jumping to a biopsy, a radiologist typically needs to:
Get a complete picture: A diagnostic mammogram is usually required (if one hasn't been done recently) to look for calcifications or structural distortions.
Assess the extent of disease: An axillary ultrasound may be needed to check the lymph nodes.
Verify the findings: The radiologist may need to personally scan the patient to confirm screening findings or clear up any ambiguities.
Plus, diagnostic imaging evaluation gives the radiologist a chance to directly discuss the findings and next steps with the patient.