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Breast Imaging or mammogram is an x-ray of the breast used to detect and diagnose breast diseases. There are two different types of mammograms. The most common is a screening mammogram, used to detect small growths in the breast, even before they can be felt. A diagnostic mammogram is used to diagnose breast abnormalities, such as a lump, pain, nipple thickening or a change in breast size or shape, which may be detected in a screening mammogram.

Greenwich Hospital performs 3-D mammography, also known as digital breast tomosynthesis. This technology allows the radiologist to view the breast in thin ‘slices’ in addition to the conventional mammogram. Studies have shown that this technique can lead to an increase in cancer detection by as much as 33%, regardless of breast density, and a 10-20% reduction in patient callbacks from screening for additional imaging. The 3-D imaging is performed simultaneously so the length of your exam will NOT change with the 2-D and 3-D images. The total radiation dose for breast tomosynthesis is less than the dose you received in prior years at Greenwich Hospital because of advancements in digital technology.

If you usually get an ultrasound for additional screening due to your breast density, the recommendation is to continue to do so. There are no studies to suggest that tomosynthesis replaces breast ultrasound as complementary breast screening.

Women who are pregnant or breastfeeding should not have a screening mammogram.

Women who have breast implants should alert the mammographer prior to their exams.

Our Technologists

At the Breast Center, digital mammography is performed by experienced technologists on state-of-the-art equipment certified by the U.S. Food and Drug Administration. All of our mammography technologists have been awarded advanced certification by the American Registry of Radiologic Technologists and are licensed by the State of Connecticut.

It is a not uncommon for the doctor to request additional films before making a final evaluation.

Screening Mammography

Screening mammograms for women who have no signs or symptoms of potential breast problem are used to help detect breast cancer. On the day of your test, the technologist will greet you and review your medical history. Next, the technologist will explain the test and answer any questions you may have. Once the images are acquired, the technologist will allow you to leave and a letter with your results will be mailed to you after 5 working days.

A small percentage of women have questionable abnormalities that may require additional imaging. These patients return to the Breast Center to have more images taken and receive the results during the appointment. There are three types of additional imaging:

  • Spot Compression views are done when a mammogram shows increased density. In many cases, overlapping breast tissue creates a false shadow. The technologist uses a smaller compression paddle directly on the density, which causes the tissue to spread. Results are usually benign.
  • Magnification views are detailed images of a questionable area of calcifications in breast tissue. These typically are not cancerous.
  • Ultrasound may be performed to evaluate a lump that is visible on a mammogram or to evaluate an area of dense tissue.

Diagnostic Mammography

A more detailed diagnostic mammogram may be performed if:

  • New symptoms develop, such as a lump or nipple discharge
  • A previous abnormal mammogram calls for close follow-up
  • A history of breast cancer exists

Diagnostic mammograms are read by the radiologist while the patient waits. If additional imaging is needed, it will be done at that time.

Unlike screening mammograms, women need a prescription for a diagnostic mammogram. Many insurance companies will not cover diagnostic mammograms for patients who do not meet the criteria for this procedure.

Breast Density and Screening Ultrasound

Under Connecticut law, all women who have mammograms receive a letter with their test results and breast density classification. The letter will also contain information about the possible benefits of ultrasound for women with moderately dense or dense breasts. The recommendations in this letter, however, are not based on any new recommendations from the scientific community. This information is meant to educate women according to state law.

Breast density refers to the relative amount of fat in the breast (which appears black on an X-ray) to breast tissue (which appears white on an X-ray). Moderately dense or dense tissue may obscure a small tumor on mammography. The ability to detect calcifications on mammography is not significantly impacted by breast density.

Who should get a screening ultrasound?

No recommendations from the medical community exist regarding screening ultrasound in women of average risk.

In a small number of women with moderately dense or dense breasts, breast ultrasound may detect small tumors obscured by dense breast tissue. Women need a prescription from their doctor to undergo a screening ultrasound.

Some insurance companies may not cover a screening ultrasound. For women who live in Connecticut, the law states that an insurer must provide additional benefits for comprehensive ultrasound screening if a mammogram demonstrates moderate or dense breast tissue. However, the insurance company may still not pay the whole bill. Deductibles and copays are still the patient's responsibility. Contact your insurance company to determine what, if any, amount will be your responsibility.

Breast ultrasound may be appropriate for:

  • Women with a strong family history of breast cancer
  • Women previously diagnosed with high-risk lesions such as ADH or LCIS
  • Women with a personal history of breast cancer

Ultrasound does not replace mammography

Mammography for women with moderately dense and dense breasts remains a useful tool. Ultrasound does not replace mammography because ultrasound does not pick up all solid masses or show calcifications. Only mammography can detect calcifications, which are often the first sign of early cancer.

Contact Us


General Questions

Copies of Images

Copies of Reports


Monday to Friday 8 am - 8:40 pm

Saturday 8 am - 11:40 am

Women can schedule a screening mammogram during any of these hours.

Diagnostic mammograms are only available Monday to Friday.

Patients are referred to the Breast Center by their gynecologist or primary care physicians.

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