Click
here to view ultrasound images of breast conditions.
Breast ultrasound, also known as
sonography or ultrasonography, is frequently used to evaluate breast abnormalities that
are found with screening or diagnostic
mammography or during a physician performed clinical
breast exam. Ultrasound allows significant freedom in obtaining images of the breast
from almost any orientation. Ultrasound is excellent at imaging cysts: round,
fluid-filled, pockets inside the breast. Additionally, ultrasound can often quickly
determine if a suspicious area is in fact a cyst (always non-cancerous) or an increased
density of solid tissue (dense mass) which may require a biopsy to
determine if it is malignant (cancerous).
If a patient’s ultrasound and mammogram results are both negative (no evidence of
cancer is seen), but the physician is still concerned about the thickening or mass, then
he/she may proceed further with a fine needle
aspiration biopsy (FNA) of the area.
Though breast ultrasound
has excellent contrast resolution, it lacks the detail (spatial resolution) of
conventional mammography, and therefore, ultrasound is not approved by the U.S. Food and
Drug Administration (FDA) as a screening tool for breast cancer. Rather, ultrasound is
used to investigate an abnormality detected by mammography or during a physician performed
breast exam. Currently, only mammography is FDA approved to look for breast cancer in
asymptomatic women (women with no signs or symptoms of breast cancer).
What Can Ultrasound
Show?
Physicians use ultrasound to evaluate
breast abnormalities that have been found with screening or diagnostic mammography or
during a clinical breast exam. Ultrasound may help detect some breast masses and is the
best way to determine whether a cyst is present without placing a needle into the area of
concern to aspirate fluid. Ultrasound is also useful in helping physicians guide a biopsy (tissue sampling) to determine whether a breast abnormality is
cancerous. Physicians use ultrasound during core
and fine needle aspiration biopsies (FNA) to
determine where to place the needle. Ultrasound may also be used to prove whether a
suspicious area is a lymph node. Lymph nodes have fatty centers which are often apparent
on ultrasound images.
Ultrasound Versus
Mammography
Ultrasound has excellent contrast
resolution. This means, for example, that an area of fluid (cyst) and an area of normal
breast tissue are easy to differentiate on an ultrasound image. However, ultrasound does
not have good spatial resolution like mammography, and
therefore cannot provide as much detail as a mammogram image. Ultrasound is also unable to
image microcalcifications, tiny calcium deposits that are often the first indication of
breast cancer. Mammography, on the other hand, is excellent at imaging calcifications.
Ultrasound may be able to detect macrocalcifications (larger calcium deposits) in some
cases.
Though most true breast lumps will be
found by mammography or ultrasound, some abnormalities escape detection on both imaging
tests. For example, a lump may be able to be felt but does not appear on mammography or
ultrasound images. If this is the case, then fine needle aspiration biopsy (FNA) is often
performed. Less than 30% of all breast biopsies are cancerous. In
cases where the abnormality is not apparent on mammogram or ultrasound, the chances of
cancer are significantly less.
CONTINUED
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