What Is a Diagnostic Mammogram?

When it comes to breast cancer screenings, the word “mammogram” is what most people associate with the testing that plays a key role in diagnosing cancer. But some people may not know there are two types of mammograms – screening mammograms and diagnostic mammograms. 

These tests can be invaluable to women as they can help patients detect and diagnose breast cancer at an earlier stage. And when diagnosed early, breast cancer is very treatable, according to Jeananne Huffman, manager of radiology at the INTEGRIS Health Comprehensive Breast Center. This blog will focus on diagnostic mammograms, their role in breast cancer diagnosis and what the results mean for your overall breast health.

What’s the difference between a screening vs. diagnostic mammogram?

A mammogram is a specific type of X-ray that creates images of breast tissue. 

It is recommended that women begin annual screening mammograms at age 40. Early screening mammography may be recommended for some women if they are at high risk of developing breast cancer due to genetics or family history. 

Here are the main differences between the two types of mammograms.

Screening mammogram: This type of imaging is performed on women who have no breast symptoms or concerns. A screening mammogram uses low dose radiation and usually takes about 15 minutes. The main purpose of a screening mammogram is for preventive purposes to detect breast cancer as early as possible. Screenings are performed annually to be most effective in identifying changes in breast tissue that may be the earliest signs of cancer. 

Diagnostic mammogram: This type of imaging is performed on women with any breast changes or concerns. Diagnostic mammography is also used often in conjunction with breast ultrasound as a secondary test to further evaluate changes in breast tissue found on a screening mammogram, as well as areas that need to be closely followed for a period of time. Diagnostic exams take longer than a screening mammogram as they are directed by a radiologist and may require specialized images. 

Reasons for a diagnostic mammogram include:

• Breast lump
• Changes in breast size or shape
• Changes in skin color
• Dimpling or puckering of the skin
• Inverted or retracted nipple
• Nipple discharge
• Nipple thickening
• Pain
• Thickening in armpit or breast
• Short-term follow up
• Surgical follow up

How is mammography performed?

A screening mammogram uses two views – a top-to-bottom view (craniocaudal) and a side-to-side view (mediolateral oblique). The breast is positioned on the image detector while a paddle is lowered to compress the breast. Compression is used to separate breast tissues, providing the best possible images for cancer detection. While the mammogram positioning may seem a little awkward, your technologist is knowledgeable in the detailed standards of care. They are highly trained to offer you the best breast care by obtaining optimal images. 

A diagnostic mammogram may start off with the standard two views used in screening mammography, depending on each unique situation. A diagnostic study is tailored to the specific needs of each patient and may also incorporate specialized views and/or breast ultrasound.

Here are some additional images a radiologist directing your diagnostic mammogram may request.

Spot compression: These views utilize a specialized paddle to focus attention and compression on an area of interest. It is very helpful to distinguish actual breast masses from overlapping normal breast tissues.

Magnification views: This view uses a raised platform and specialized paddle to magnify a specific area of the breast. Magnification views are typically used to analyze breast calcifications which show up on a mammogram as tiny white dots, as small as grains of sand.

For a screening mammogram, a mammographer (specialized technologist who is trained in mammography) performs the test. They will check each image for optimal positioning, compression and exposure factors. When they are satisfied, you will be done and free to leave. You will receive your results later through the patient portal or as a letter in the mail. 

During a diagnostic mammogram, the interpreting radiologist (doctor specialized in the interpretation of mammograms) and mammography technologist work together to ensure all the necessary information and images are included in your exam. Breast ultrasound is often used in conjunction with diagnostic studies. The radiologist will determine if an ultrasound is needed after the mammogram images have been completed, and you will receive the overall results after all tests are completed before you leave.

What are the most common reasons for being recalled after a mammogram?

While many diagnostic mammograms are performed due to obvious symptoms (changes in size, shape or color of the nipples or breast), some women require a diagnostic mammogram as a follow up to abnormal or suspicious findings on a routine screening.

About 10 percent of women are recalled after a screening mammogram, which is a term used to describe situations in which patients are called back in for further examination. Women are more likely to be called back after their first mammogram. Baseline mammograms do not have the benefit of comparison from previous years’ exams to demonstrate the patient’s usual appearance of breast tissue patterns.

Getting called back after a screening mammogram isn’t uncommon, and it doesn’t mean you have cancer. Mammography is highly dependent on comparison to previous mammograms, any changes in breast tissue from year to year must be fully evaluated. In most cases, changes on mammograms are benign, and not cancer.

The following is a list of reasons why you may need a diagnostic mammogram after a screening mammogram is flagged:

• Architectural distortion: Sometimes, tissue can appear distorted or pulled and require further evaluation.
• Asymmetry: Some areas of the breast may have a different pattern than other breast tissue.
• Calcifications: Because calcifications can be the earliest detectable form of breast cancer, microcalcifications are treated with concern and respect.
• Cysts: Cysts are benign fluid-filled sacs, but they can mimic solid masses on X-ray. An ultrasound is usually needed to determine if the mass has fluid or is solid.
• Dense breast tissue: Cancer and breast tissue both appear white on a mammogram, making it harder to identify tissue. Dense tissue can obscure or hide small cancers.
• Skin thickening: Cancer can cause breast tissue to swell or become inflamed, so any changes in thickness will require further evaluation.
• Solid mass: Cysts and a solid mass can look the same on imaging, so additional views may be needed to analyze the size, shape and edges. Ultrasound is very helpful to characterize masses seen by mammography, providing additional information to the radiologist.

What the results mean

At the conclusion of a mammogram, radiologists categorize the results using the Breast Imaging Reporting and Data System (BI-RADS). A 0 to 6 scale is used to report the findings to your doctor. 

• BI-RADS 0 – Incomplete finding: The test is inconclusive and needs additional images with diagnostic mammography and/or breast ultrasound for complete evaluation.
• BI-RADS 1 – Negative finding: Nothing new or abnormal was found.
• BI-RADS 2 – Benign finding: Changes in the breast are stable and non-cancerous.
• BI-RADS 3 – Probably benign but follow-up needed: Radiologist does not suspect cancer, but short-term follow-up is recommended to watch closely for any changes over the next two years.
• BI-RADS 4 – Suspicious abnormality: The findings may be cancerous, and a biopsy is needed.
• BI-RADS 5 – Highly suggestive of malignancy: The findings look like cancer and a biopsy is needed to confirm.
• BI-RADS 6 – Known biopsy-proven malignancy: This category is only used for people who were previously diagnosed with cancer.

It’s common for women to be worried or concerned when they need a diagnostic mammogram, but the truth is the majority of findings don’t result in the need for a biopsy. 
Annual mammograms are the most proactive steps women can take toward maintaining good breast health beginning at age 40. Consult with your doctor how often you should receive a mammogram, especially if you’re at a high risk of developing breast cancer.