Mammogram and Ultrasound Images Explained

A mammogram (a combination of X-ray images of the breast) is a routine part of a breast cancer screening program.

Physicians agree that breast palpation programs (physically checking for lumps) are generally insufficient for early breast cancer detection.

Breast self-examination programs are also unreliable as a lesion can develop for years before it becomes palpable.

Of course, when a family physician finds a bump or a lump of some kind on a clinical exam, he/she will immediately refer the patient for a mammogram. Women with higher than average risk factors and older women should generally have mammograms more frequently.

Normally, the X-ray component of a mammogram is all that is necessary for breast cancer screening purposes.

So, an ultrasound is typically a ‘second look’ type of application. However, it is not a good idea to have an ultrasound instead of a mammogram and it is probably best to follow the advice of the screening physicians.

I just want to let you know that I have a newer version of this page, with more up-to-date information on Mammogram Screening Images. However, it isn’t nearly as long as this one. This page is still really useful.

Information about the lesion as seen on mammograms and ultrasounds

On a mammogram, a lesion will usually appear brighter than the surrounding tissue. This is because things that are denser than fat will stop more x-ray photons, hence they appear brighter.

Ultrasounds are a little harder to figure out. The darkest images on a sonograph are cysts containing liquid. Solids are less definitive. With ultrasound, the radiologist will probably be trying to get a sense of the internal texture of the breast lesion and surrounding area.

Solid lesions can be a little brighter or darker than the surrounding tissue, and the way to evaluate these on ultrasound is to look closely at the margins or the outer edges of the nodule.

Examples of breast cancer screening mammography interpretation

Even with ill-defined borders and spiculated margins, other factors make breast cancer an unlikely diagnosis

The X-ray image below shows a suspect breast mass of about 1 cm in diameter. Some architectural distortion is also apparent.

An ultrasound image of the same lesion suggests that the lesion is solid. The mass appears to be hypoechoic with ill-defined, spiculated, and microlobulated margins.

It is not possible to rule out malignancy here because posterior acoustic shadowing is not present. When a lesion is homogeneous, good ‘through-transmission’ of the ultrasound beam is possible, and malignant breast cancer lesions are typically not so homogeneous.

Asymmetric breast density often has benign causes

The X-ray image below shows a lesion with asymmetric density. That indicates that the lesion likely contains a variety of elements, which may or may not indicate breast cancer.

On the sonogram below, the asymmetric density observed in the X-ray appears to be fat tissue. This is due to the fact that although it is a little darker-appearing on ultrasound than other fat, it has an internal texture resembling a fat lobule.

There is an apparent capsule, which is the thin bright line around the outside of the dark oval area. (A capsule is a fibrous covering that surrounds some things like lipomas). This suggests the lesion might be hamartoma or fibroadenolipoma, but as there is no apparent capsule on the X-ray, this is less likely.

Usually, in a post-traumatic or post-operative hematoma, there would be a collection of solid and liquid components, and that does not appear to be the case here.

The site requires further investigation, perhaps by spot films with compression, (which gives a more detailed view of the lesion itself and not the surrounding breast tissue). Likely diagnosis might be fibroglandular dysplasia or other fibrocystic changes.

Scar tissue can often appear suspicious

The image below contains a lesion with irregular, spiculated margins. There does not appear to be a central mass to this lesion, which right away makes it less likely to be breast cancer. However, something this suspicious would likely need a biopsy to find out exactly what is going on.

This lesion is more likely to be either a post-surgical scar or possibly a radial scar. In actual fact this particular image was taken from a woman who had breast surgery, so a post-surgical scar is the most probable diagnosis.

A closer look via magnification of the same lesion reveals a central radio-transparency likely caused by fat necrosis, and there is no central mass.

The spiculations around the lesion are likely a desmoplastic reaction to the surgery. (‘desmoplasia’ refers to the growth of fibrous and connective tissues. This is common following surgery, and is often more commonly known as scar tissue).

Male Breast Ultrasound: Gynecomastia versus breast cancer

Male breast cancer is very rare, but one condition, gynecomastia, which is the development of abnormally large breasts in men, is quite common. Gynecomastia is usually caused by excessive growth of fibroglandular breast tissue in men in their 60’s or as the result of hormonal imbalances.

However, in rare cases, breast cancer can be the cause of gynecomastia so, a full mammographic investigation is always necessary.

In the mammogram below, one can see the increase in the density of the fibroglandular tissues behind the nipple. It appears to be developing in a concentric pattern. The contour of the dense area is concave-outward and interspersed with fat.

There are no well-formed masses and no suspicious microcalcifications. It certainly would appear to be gynecomastia from natural or hormonal causes and not breast cancer.

In the sonogram of the same breast, one notes that the density appears hypoechoic with ill-defined margins. The amount of tissue appears to be thicker than average in a male but the only way to know if anything abnormal is going on in the sonogram would be to compare it with an ultrasound of the other breast to see if the densities are about the same.

Lactating Adenomas in Mammogram Images

Breast cancer is very uncommon in younger women. So, if a young woman who is pregnant came in for a screening of a palpable breast lump it is far more likely that the lesion is a fibroadenoma of some kind.

One common variation of fibroadenoma in pregnant women is a lactating adenoma, which is essentially a tubular adenoma that occurs in pregnant women. Lactating adenoma features the accumulation of milk secretions in addition to hyperplasia.

Breast X-rays are not normally given to pregnant women. Given that breast cancer is very unlikely and lactating adenoma is quite likely, ultrasound and possibly a fine needle aspiration biopsy would typically be utilized for diagnostic investigations.

The main concern with a lactating adenoma from the perspective of breast cancer is that the condition can occur simultaneously with breast cancer. However, on their own, they indicate no increase in the risk for subsequent breast cancer development.

In the ultrasound image of lactating adenoma below, one notes a hypoechoic, non-cystic mass in an ovoid shape. It has a long axis running parallel to the skin, posterior acoustic enhancement, and well-defined margins.

More about Lactating Adenomas in Mammogram Images

Mammograms of lactating adenomas (not generally given to pregnant women) will tend to show an oval well-circumscribed mass with radiolucent (somewhat transparent) central areas (radiolucent features will appear darker on an X-ray).

Ultrasounds of lactating adenomas tend to reveal the heterogeneous echotexture of the tumor, with central hyperechogenic areas. The radiolucent (X-ray) and hyperechogenic (ultrasound) areas will indicate the fat content of the milk secretions in the tumor.

Since lactating adenomas occur in pregnant and breastfeeding women, this tends to simplify diagnosis. An abscess, for example, would be unlikely in the absence of:-

erythema (redness often due to inflammation)
skin edema (a bulge caused by the build-up of fluids)

Lactating adenomas also tend to be only slightly painful, unlike an abscess. But, to exclude any possibility of malignancy a fine needle biopsy is usually performed anyways.

Fine needle biopsy is actually preferred over a core biopsy in suspected lactating adenomas because milk secretions can ‘find their own paths’ through various tissues and confuse the issue.

In the cytologic image of lactating adenoma below, there are many more ducts than would normally occur (hyperplasia). The ducts are dilated and contain milk secretions. The proliferation of new ducts distinguishes the lesion from a simple galactocele, which is just an accumulation of milk that cannot escape through normal channels.

Cytology of Lactating Adenoma

Lactating adenomas, like fibroadenomas, are somewhat prone to infarction (tissue death from compromised blood supply), and this can lead to some strange and misleading features, possibly suggestive of malignant breast cancer.

Some of these features may include:-

structural heteroechogenicity
microlobulated margins
pronounced hypoechogenicity
posterior acoustic shadowing
irregularly shaped masses

If there are any of the above features a fine needle biopsy may be necessary.

Interpreting breast cancer screening mammograms improves with experience

It takes years of radiological experience to gain experience and knowledge in interpreting mammograms. However, anything abnormal, and especially features which show unusual density, odd shapes, and irregular borders, will need a biopsy.

Interpretation accuracy improves over the first three years of practice and continues to be refined over the course of a radiologist’s career. For some reason, the rate of abnormal findings on mammograms is slightly higher in North America than in Europe.

Let’s do some Q&A about Mammography…

How are mammograms done?

During a mammogram, your breasts are compressed between two firm surfaces to spread out the breast tissue. Then, an x-ray captures black and white images of your breasts that are displayed on a computer screen and examined by a doctor who looks for signs of cancer.

How can mammograms be used?

A mammogram can be used either for screening or for diagnostic purposes.

How often should you have a mammogram?

It all depends on your age and your risk of breast cancer.

How do I know when I should begin screening mammography?

Some general guidelines for when to begin screening mammography include women with an average risk of breast cancer and woman with a high risk of breast cancer.

What are the risks?

Some known risks and limitations of mammograms include the following: Mammograms:-

expose you to low-dose radiation
are not always accurate
can be difficult to interpret in younger women
may lead to additional testing
can not detect all breast cancers
may show cancer, but not all of the tumors can be cured

How do I prepare for my mammogram appointment?

Choose a certified mammogram facility
schedule the test for a time when your breasts are least likely to be tender
bring your prior mammogram images
do not use deodorant before your mammogram
consider an over-the-counter pain medication if you find that having a mammogram is uncomfortable.

What can a radiologist possibly find on my mammogram imaging?

Well, possible findings can include:-

calcium deposits
masses or lumps
distorted tissues
dense areas appearing in only one breast or one specific area on the mammogram
a new dense area not present on your last mammogram.

References

Sickles A, Periodic Mammographic Follow-up of Probably Benign Lesions, Radiology 1991; 179:463-468.
Hagan-Absert, Sandra, Textbook of Diagnostic Ultrasonography, Mosby, (c)2001.
Yang, Wei Tse., Whitman,Gary J., . Yuen,Edmund H. Y., Tse, Gary M. K., and Stelling, Carol B. .Sonographic Features of Primary Breast Cancer in Men. AJR 2001; 176:413-416
Berg WA. Letters. AJR; 181:1427, Nov. 2003.
Kopans DB. Negative Mammographic and US Findings Do Not Help Exclude Breast Cancer. Radiology Volume 222, N 3: 857- 858, March 2002.
Paquette D, Snider J, Bouchard F, Olivotto H, for the Canadian Breast Cancer Screening Initiative. Performance of screening mammography in organized programs in Canada in 1996, CMAJ 2000;163(9):1133-8
Sickles EA , Wolverton DE, Dee KE. Performance Parameters for Screening and Diagnostic Mammography: Specialist and general Radiologists. Radiology 2002; 224: 861-869.

More References

Sabate, J.M., Clotet, M., Torrubia, S., Gomez, A., Guerrero, R., de Las Heras, P., Lerma, E. Radiologic Evaluation of Breast Disorders Related to Pregnancy and Lactation; RadioGraphics, (October 2007)27, S101-S124.
Elmore JG, Nakano CY, Koepsell TD, Desnick LM, D’Orsi CJ, Ransohoff DF.International variation in screening mammography interpretations in community-based programs. J Natl Cancer Inst. 2003 Sep 17;95(18):1384-93.
Miglioretti DL, Gard CC, Carney PA, Onega TL, Buist DS, Sickles EA, Kerlikowske K, Rosenberg RD, Yankaskas BC, Geller BM, Elmore JG. When radiologists perform best: the learning curve in screening mammogram interpretation.Radiology. 2009 Dec;253(3):632-40.
Feldman J, Smith RA, Giusti R, DeBuono B, Fulton JP, Scott HD.Peer review of mammography interpretations in a breast cancer screening program. Am J Public Health. 1995 Jun;85(6):837-9.
Sickles, EA., Successful methods to reduce false-positive mammography interpretations. Radiologic Clinics of North America Volume 38, Issue 4, Pages 693-700
Birdwell RL, Ikeda DM, O’Shaughnessy KF, Sickles EA. Mammographic characteristics of 115 missed cancers later detected with screening mammography and the potential utility of computer-aided detection. Radiology. Apr 2001;219(1):192-202
van Engeland, S., Karssemeijer, N., Matching Breast Lesions in Multiple Mammographic Views. Lecture Notes in Computer Science, 2001, Volume 2208/2001, 1172-1173,
Wang, J., Shih, TTF., Hsu, JCY, Li, YW. The evaluation of false negative mammography from malignant and benign breast lesions.(March 2000_Volume 24, Issue 2, Pages 96-103