Mammograms, Ultrasounds and MRIs: What's the Difference?
Oct 08, 2021 Amy Paturel
"Women should consider 3D mammograms, especially if they have dense breasts. 3D screening mammography can increase the cancer detection rate in some cases, and studies suggest it can also reduce patient callbacks by up to 30%."
"Studies show that routine breast cancer screening can reduce breast cancer deaths by one third and 40-50% in some trials," says Dr. Cynthia A. Litwer, a radiologist at Cedars-Sinai. "Finding breast cancer early can save lives and help avoid more extensive treatment."
Many technologies, one goal: better screening
While health authorities often issue sweeping guidelines, the reality is there's no one-size-fits-all approach to breast cancer screening. Instead, doctors consider a range of factors, such as your family and medical history and the density of your breast tissue, to help guide decisions about breast cancer screening.
"We recommend all women get a risk evaluation for breast cancer at age 30 to help determine their personal risk and devise a screening schedule that makes sense for their unique circumstances," Dr. Litwer says.
So, whether you're getting a routine screening, you've found a lump or you're experiencing unexplained pain, doctors use a full range of options that work together to detect cancers in their earliest stages when they're easiest to treat. A few of the most discussed methods:
A screening mammogram is a low-dose imaging test that helps doctors spot changes in breast tissue. During the 10-minute procedure, a technician places your breasts—one at a time—between two imaging plates. Applying pressure to the plates produces a more detailed image with a lower dose of radiation.
Health authorities, including the American College of Radiology and the Society of Breast Imaging, recommend people begin annual screening mammograms at age 40. But even within mammography, you have options:
- 2D mammography: 2D digital mammography captures two X-ray images of the breast, one from the top and one from the side. These are flat, 2-dimensional images, which means overlapping tissue can hide abnormalities that could be signs of cancer. "2D mammograms are still important, particularly for magnifying and characterizing calcifications that commonly occur in breast tissue," Dr. Litwer says.
- 3D mammography or digital breast tomosynthesis (DBT): With 3D mammography, the imaging system moves in an arc over the breast, taking multiple X-ray images from various angles. With the help of artificial intelligence, radiologists review 200 to 300 images with 3D mammography compared to only four with 2D technology.
"Women should consider 3D mammograms, especially if they have dense breasts," Dr. Litwer says. "3D screening mammography can increase the cancer detection rate in some cases, and studies suggest it can also reduce patient callbacks by up to 30%."
If you have a palpable lump, localized pain in your breast or have noticed skin/nipple changes or nipple discharge, your doctor may order a diagnostic mammogram. With a diagnostic mammogram, a radiologist orders specialized 2D and/or 3D mammographic views, such as magnification and spot compression, and reviews the images in real time. That way, if further imaging is necessary, it happens at the time of your visit.
One cautionary note: If you're getting vaccinated against COVID-19, or influenza, schedule your screening exams before your first COVID-19 shot or four to six weeks after your second vaccine dose. Vaccination can cause your lymph nodes to temporarily swell. While swollen lymph nodes from the vaccine indicate a strong immune response, they can show up on mammograms and require additional imaging and follow up. Do not delay any diagnostic screening for any other reason.
Ultrasound uses sound waves to image the breast. Ultrasound can be especially useful among individuals who have dense breasts, but it should not be used as a substitute for a mammogram.
- Handheld ultrasound: Doctors usually recommend targeted handheld diagnostic ultrasound when mammography finding requires additional investigation, or as a screening method in conjunction with mammography when you have a lump, localized pain in the breast, skin/nipple changes or nipple discharge.
- Automated whole breast screening ultrasound (ABUS): ABUS surveys each breast with a large transducer in three sweeps. " ABUS can be helpful for supplemental screening in patients who have a high risk of breast cancer, as well as in average-risk individuals who have very dense breasts," Dr. Litwer says. Doctors may also use ABUS to evaluate whole breast pain and breast tenderness.
Magnetic Resonance Imaging (MRI)
MRI technology relies on the magnetic field and radiofrequency waves to produce images. With breast cancer screening, doctors retrieve images of the breasts before and after you receive an intravenous contrast solution that helps enhance the appearance of abnormal tissue.
"Breast MRI is extremely sensitive for picking up breast cancers, which is why we use it as an additional screening tool for those who have a genetic-based increased risk of breast cancer and those who have a personal history or strong family history of breast cancer," Dr. Litwer says. Doctors may also order a breast MRI to clarify uncertain findings from a mammogram or ultrasound.
Unfortunately, as a stand-alone screening tool, MRI increases the odds of radiologists detecting suspicious tissue that isn't cancerous, which may require additional testing.
What if screening uncovers a suspicious finding?
Whether your screening includes mammography, ultrasound or MRI—or some combination of all three—false positive findings can occur. A false positive screening exam happens when the patient is called back for further workup of a finding that ultimately does not turn out to be cancer.
"The chances of having a false positive result is greater with a baseline mammogram. Studies show that women who have prior mammograms for comparison have fewer false positives," Dr. Litwer says. These false findings are also more common among patients who:
- Are between the ages of 40 and 49
- Have dense breasts
- Have a prior benign biopsy
- Have a family history of breast cancer
- Are taking hormone replacement therapy
"Callbacks on screening mammography are not uncommon, but a very small percentage of the number of cases we call back turn out to be cancer," Dr. Litwer says. "If you do happen to get called back, you'll get additional specialized imaging to make sure you don't have cancer. If it is cancer, the additional workup will have helped diagnose it early and that's a good thing!"