The breast is a difficult organ to image due to dense tissue, monthly hormonal changes and age-related changes that develop over time. The 3 most commonly used methods of breast imaging are mammography, ultrasound, and MRI.
A mammogram is a low-dose x-ray of the breast, and is the primary method for screening for breast cancer. Currently, most facilities offer digital mammography. This offers a much more detailed view than the previously used film screen technique.
Some facilities offer 3D mammography, also known as tomosynthesis. This form of mammogram has been shown to improve the rate of breast cancer detection, although there are no studies showing that this improves outcomes. Tomosynthesis is helpful primarily in women with dense breast tissue, and can reduce the callback rate – the need to return for additional views. There is a slightly higher associated dose of radiation compared to standard digital mammography. Some insurance companies still consider tomosynthesis to be experimental, so they may not cover it even when ordered as a screening test. Check with your insurance company and with the facility. Some facilities do not charge extra even when insurance does not cover the study.
A screening mammogram is considered a “routine check”, and assumes there are no abnormalities. The Affordable Care Act requires that all insurance companies cover this procedure without charge or copay. 2 views of each breast are taken. Images are reviewed by the radiologist, compared to prior studies if available, and a report is generated – usually this is not done on the same day. The patient is informed of the results in writing by the facility, and the referring doctor receives a copy of the report.
Diagnostic mammograms are performed when an abnormality is noted on exam (such as a lump, pain, or nipple discharge) or as a “callback exam” when an abnormality is noted on screening. An ultrasound might also be performed. The imaging will focus on the area of abnormality. The radiologist will normally review the findings of a diagnostic study with the patient in addition to informing her referring physician. Insurance may not cover diagnostic imaging – this will depend on your insurance coverage and the facility billing. In patients who have been treated for breast cancer, a diagnostic mammogram is often ordered at the completion of treatment. If there are no specific abnormalities, both the NCCN and ASCO guidelines recommend that patients resume annual screening if there are no abnormalities noted on exam. However, some imaging facilities have their own policies regarding the frequency of diagnostic imaging after treatment for breast cancer.
When preparing for a mammogram, it is important not to use deodorant, lotions, or perfumes – particles in these toiletries can appear as false alarms on mammograms. Most mammography technologists will place a small wire over a scar from prior surgery – inform the technologist if you have had prior breast surgery. In addition, large skin moles or tags will also be marked. Some women experience pain when they undergo mammograms. In women having regular menstrual periods, obtaining the mammogram after your menstrual cycle when the breasts are less tender is an option. Over the counter medications such as acetaminophen (Tylenol) or ibuprofen may also help. Notify the technologist if you are experiencing extreme pain during the procedure.
As mammogram technology has improved, concerns have been raised about overdiagnosis – finding small cancers and other abnormalities that are not destined to become a threat. However, as we are not always able to predict with certainty which lesions may eventually pose harm, we generally recommend treatment once an abnormality is detected – even though we know not all women will need it, and some may be harmed from the treatment. Overdiagnosis is one of the reasons that many national organizations such as the American Cancer Society no longer recommend annual mammograms for all women.
Ultrasound uses sound waves to image the breast. As with mammography, ultrasound may miss small masses and areas of distortion, and typically is not helpful to detect calcifications. Ultrasound is not meant to be a substitute for mammography. In women with dense breast tissue, supplemental screening with ultrasound has been shown to find additional cancers (compared to mammography alone) but studies have not yet shown if this leads to better outcomes. In some states, local laws require that insurance companies pay for supplemental ultrasound in women with dense breast tissue. There is no such law in California. Most often, ultrasounds are billed as diagnostic studies by the facility (even though it might be ordered as a “screening” ultrasound, the billing codes that currently exist are all for “diagnostic” breast ultrasound), so they may not be covered by insurance. Automated whole breast ultrasound (ABUS) is a newer form of ultrasound which is less operator-dependent. It is not generally covered by insurance. Studies have not yet shown whether or not this type of ultrasound finds more cancers or results in improved outcomes.
Breast magnetic resonance imaging (MRI) is recommended for patients who are considered high risk (usually due to family history of breast cancer or pre-cancerous changes on previous biopsy) and those who are known carriers of certain genetic mutations which predispose them to breast cancer. MRI can be helpful in assessing a newly-diagnosed breast cancer patient. However, studies have not shown that preoperative MRI improves outcomes and the recommendation for the study is generally on a case-by-case basis. Breast MRI exams are associated with an approximately 10-20% “false alarm” rate – suspicious appearing findings may be noted which result in additional imaging and even biopsy. Recently, the safety of the contrast material used for MRI, gadolinium, has been called into question, but there is limited information as far as potential long-term effects.
It is important to remember that no imaging study is perfect – detection of cancer can be limited in patients with dense breast tissue, and it can be difficult to examine the deepest part of the breast along the chest wall. Cancers can be missed even when using all of our imaging tools. Therefore, it is also important to be “breast self-aware” and report any changes or concerns to your physician, even if your mammogram is normal.
Dr. Attai does not provide online medical advice. The information provided is for general information only.
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