BREAST ULTRASOUND AND
BREAST PROCEDURES
7
Susan P. Weinstein, MD
1. What are the labeled structures on the ultrasound (US) image in Fig. 7-1?
The structures are skin (A ), subcutaneous fat (B ), glandular tissue (C ), fat (D ), muscle (E ), and rib (F ).
2. What type of transducer should be
A
used to perform breast US?
B
A linear array transducer should be used. It should
be at least 7 MHz, ideally 10 MHz or greater.
3. List the indications for breast US
after a mammographic evaluation.
" To evaluate a palpable abnormality further. D
" To characterize a mammographic finding or
C
abnormality.
4. In what situations would you not
perform a mammogram but go
directly to breast US in evaluating
patients with palpable breast masses?
In patients who are younger than 30 and in pregnant
E
patients, it is recommended to go directly to breast
US. For all other patients, mammography should be
obtained first. At our institution, a mammogram is
obtained first in women who are older than 30. To
evaluate the palpable abnormality further, US follows
F
the mammogram. If the patient is younger than 30,
US is obtained first. Age 30 is an arbitrary number;
different institutions may have a different cutoff age.
Figure 7-1. US image of normal breast tissue.
5. What are some suspicious lesion
features on US?
Suspicious features on US include a markedly
hypoechoic appearance, posterior acoustic
shadowing, angular margins, spiculations,
microlobulations, a mass that is taller than wide,
and ductal extension. Although these features
are usually seen in malignant lesions, there is an
overlap, and benign masses may also exhibit some
of these findings (Fig. 7-2).
6. What are some benign lesion
features on US?
Benign features on US include absence of
malignant features, well-circumscribed
mass, ellipsoid shape, macrolobulations, and
hyperechogenicity. Although these features are
typically seen in benign lesions, some malignant
masses may exhibit some of these features. Well-
circumscribed cancers include invasive ductal
Figure 7-2. Highly suspicious hypoechoic lobulated solid mass with
carcinoma (not otherwise specified) and medullary irregular margins in a woman who presented with a palpable breast
mass. Biopsy revealed invasive carcinoma.
and colloid subtypes of ductal carcinoma (Fig. 7-3).
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7. What types of biopsy procedures
may be performed to evaluate breast
lesions?
Fine needle aspiration (FNA) is readily available
and needs no special equipment. Overall, it is less
traumatic than core biopsy or excisional biopsy.
Core needle biopsy is a minimally invasive
percutaneous procedure that can be performed
under US guidance or stereotactic mammographic
guidance. A wide range of needles is available
on the market in terms of needle gauge and
vacuum versus nonvacuum assistance. The type of
needle that is used tends to be based on personal
preferences, although stereotactic biopsies are
almost always done with vacuum assistance to
Figure 7-3. A 26-year-old woman presented with a palpable mass. US
maximize the retrieval of calcifications. Biopsies
shows a benign-appearing, well-circumscribed oval mass. US findings
performed under US tend to be easier and faster
are consistent with a benign mass such as a fibroadenoma.
to perform than stereotactic biopsies, partly
because of the real-time imaging available with US guidance. At our institution, we reserve the stereotactic method
to obtain biopsy samples of calcifications, although biopsy samples of solid masses may also be obtained using this
method. Percutaneous core biopsies are less expensive, are faster to perform, and are less traumatic than surgical
biopsies. The false-negative rates are similar to open biopsies.
Needle localization followed by excisional biopsy in the operating room is the gold standard. To confirm removal of the
lesion, a specimen radiograph is obtained. At our institution, we image the specimen while the patient is still in the
operating room. The findings are called to the surgeon.
8. What are the relative disadvantages of FNA, core needle biopsy, and needle
localization/excision?
" FNA: The results depend on the skill of the individual performing the procedure and the cytopathologist. There can
be a high percentage of unsatisfactory aspirates (20% to 30% of cases). Invasive versus in situ cancer cannot be
differentiated on FNA. The false-negative rate for image-guided FNA is unknown.
" Core needle biopsy : Tissue displacement may occur during the biopsy procedure, resulting in misinterpretation of
intraductal carcinoma as invasive carcinoma. Inversely, cancer can occasionally be understaged.
" Needle localization with excisional biopsy : This is the most expensive and most traumatic of all the biopsy procedures.
9. After core biopsy, how can one be certain that the lesion of interest was actually
what was sampled?
After a stereotactic biopsy, a specimen radiograph is used to confirm that representative amounts of the targeted
calcifications are in the specimen. Real-time visualization during the US-guided biopsy confirms that samples of the
appropriate area of concern were obtained.
10. What is stereotaxis?
Stereotaxis is a technique used to localize breast lesions for biopsy. A digital image of the lesion, the scout image, is
taken on the stereotactic machine. This image is obtained at 0 degrees. Two views are taken at ą15 degrees from the
original 0-degree scout image. From the three views, the machine calculates the z axis, which is the depth the needle
needs to be placed to obtain a biopsy sample of the lesion.
Key Points: Ultrasound/Interventional
Procedures
1. For optimal imaging evaluation, at least a 7-MHz
transducer (ideally e"10 MHz) should be used to perform
breast US.
2. In addition to doing the percutaneous breast biopsy,
the radiologist s role includes evaluating the pathology
results for concordance with the imaging findings.
3. If atypical ductal hyperplasia is present on pathologic
evaluation of a percutaneous biopsy specimen,
excisional biopsy should be recommended.
44 BREAST ULTRASOUND AND BREAST PROCEDURES
11. In what circumstances would stereotactic biopsy be difficult to perform?
" Lesions in the subareolar location.
" If the breast tissue is thin. Compression thickness of less than 2.5 cm may make biopsy sampling difficult.
" Lesions that are very posterior in location.
" If the calcifications are indistinct and difficult to see. The calcifications need to be easily visible to target them
appropriately for biopsy sampling. A loosely grouped cluster would also make targeting difficult. A tight cluster would
be easier to target for biopsy sampling.
12. In what circumstances would a US-guided biopsy be difficult to perform?
" Lesions that are very small and close to the skin surface.
" Lesions behind the nipple.
" Lesions close to the chest wall.
13. What is discordance in relation to percutaneous biopsies?
When a percutaneous breast biopsy is performed, one of the radiologist s roles is to ensure the histologic diagnosis
is concordant, or makes sense with the imaging appearance. If the imaging appearance is highly suspicious, and the
pathologic results are benign, this may suggest a discordance. If there is discordance, the radiologist may suggest
excisional biopsy for further evaluation.
14. In what situations or histologic diagnosis should an excisional biopsy be
recommended after a percutaneous breast biopsy?
When there is pathologic-imaging discordance, excisional biopsy should be recommended. When atypical ductal
hyperplasia is present on pathologic evaluation, excisional biopsy should also be recommended. When atypical ductal
hyperplasia is present, cancer is present on excisional biopsy 20% to 56% (14G needle) and 0% to 38% (11G needle)
of the time. Other controversial pathologic diagnoses include papillary lesions, radial scars, atypical lobular hyperplasia,
and lobular carcinoma in situ. The literature would advocate excisional biopsy for these lesions as well.
BIBLIOGRAPHY
[1] G. Gardenosa, Breast Imaging Companion, third ed., Lippincott Williams & Wilkins, Philadelphia, 2007.
[2] D.B. Kopans, Breast Imaging, third ed., Lippincott Williams & Wilkins, Philadelphia, 2007.
[3] L. Liberman, Percutaneous image-guided core breast biopsy, Radiol. Clin. North Am. 40 (2002) 483 500.