Magnetic Resonance Imaging (MRI)

For women with a high risk of developing breast cancer (a genetic mutation or strong family history of breast cancer), a more aggressive schedule of screening may be advisable. High-risk women are more likely to develop breast cancer before the age of 40, when women normally start having screening mammograms. They're also more likely to have fast-growing cancers that can develop between mammograms. Mammograms are less effective in younger women because their breasts tend to be more dense, making mammogram images harder to read. In addition, some types of tumors that high-risk women may develop are less apparent on mammograms.

Breast MRI doesn't use X-rays or expose the patient to radiation. It uses magnetic energy and radiowaves to produce hundreds of images of the breast from multiple angles. Unlike mammograms, MRI can produce images of breast implants and tissue that may be obscured behind them. Breast MRIs use a contrast agent called gadolinium, injected through an intravenous (IV) line, that causes tumors to "light up" in the MRI image.

Women at high risk may want to talk to their doctor about supplementing their mammogram screenings with MRI screening, beginning at age 30. MRI screening can detect even very small tumors, and can find tumors even in very dense breasts. (On the other hand, mammograms are better able to find cases of ductal carcinoma in situ [DCIS], considered to be a precursor to invasive breast cancer.) The combined sensitivity of MRI plus mammography is about 95%, meaning that together they catch about 95% of cancerous lesions in the breast.

However, MRI screening isn't appropriate for women at average risk. MRIs are very expensive, costing about 10 times what a mammogram costs. They are considered invasive because a contrast agent is injected. MRI exams also generate a number of false-positive results (suspicious areas that warrant further investigation, but turn out not to be cancer). One study showed that MRI screening led to twice as many unneeded additional exams and three times as many unneeded biopsies. These drawbacks make MRIs an impractical tool for women who aren't particularly likely to develop breast cancer. But for women at high risk, the false positives are a worthwhile tradeoff. For these women, the first priority is to detect cancer early.


What to Expect When You Have an MRI Scan


What does the MRI unit look like?

Traditional MRI units are large cylinders that the exam table slides into. With short-bore systems and open MRI units, the patient isn't completely enclosed.

How Is the MRI Exam Done?

• You will lie on top of the movable exam table with your breasts hanging down into two cushioned recesses.
• While you are in the MRI unit, a contrast agent will be administered through an IV line implanted in your hand or arm.
• MRI scans are noisy, so you may want to use earplugs.
• MRI sessions usually last from 30 minutes to 1 hour. The total exam is usually completed within an hour and a half.

After the Exam

• You may be asked to wait while the technologist checks to see if more images are needed.
• The radiologist will send a copy of the results to your doctor.

Ultrasound

Ultrasound can be used for early detection of breast cancer. Early detection evaluates abnormalities that have been found with screening: lumps detected in a mammogram, or big enough to be felt with BSE or CBE. Ultrasound alone isn't used for screening because it doesn't produce an accurate image of the entire breast and gives a large number of false-positive and false-negative results.

A big advantage of ultrasound is that it can distinguish with close to 100% accuracy whether a mass is solid, as cancers are, or a hollow cyst filled with fluid. If the mass is solid, further tests will be necessary for diagnosis. Ultrasound may also be used to guide the needle for biopsies of a suspicious mass.

For women at higher-than-average risk of breast cancer and women with dense breast tissue, ultrasound in combination with mammography has been found to reveal more breast tumors than mammography alone. One drawback of using ultrasound is that it does increase the rate of false-positive findings and unnecessary biopsies. There doesn't seem to be any added benefit to using ultrasound in combination with MRI screening.

Ultrasound is based on the same principle as radar: it sends sound waves into the body and uses a computer to transform their echoes into an image for analysis. It is simple and painless to have an ultrasound. The patient lies on a table and a gel is applied to the breast as a lubricant. The ultrasound probe is moved over the breast with a sliding motion.

Some abnormalities a mammogram detects won't be visible on an ultrasound. In this case, the radiologist must base his or her recommendations on the mammogram results.

Why Are Ultrasounds Performed?

Breast ultrasounds may be done if a clinical exam or mammogram has revealed an abnormality and the ultrasound may provide more information about it. For instance, an ultrasound may reveal a lump to be a hollow cyst rather than a cancerous tumor. Ultrasounds may also be done to image dense breast tissue and breast tissue that is obscured by breast implants. Women under the age of 25 who are at high risk for breast cancer, but who are concerned about radiation exposure, may have ultrasounds instead of mammograms. And women who are pregnant, and so should not be exposed to radiation, may have them instead of mammograms as well.


What to Expect When You Have an Ultrasound Exam


Preparing for the Exam

• Describe any symptoms or problems to the ultrasound operator.
• If you have breast implants, tell the operator. How Is the Ultrasound Exam Done?
• You'll lie on an exam table and gel will be smoothed on the area to be examined.
• The ultrasound operator will glide the ultrasound transducer (wand) over your skin and watch the images on a computer monitor.
• Any areas of concern will be imaged and measured.
• The exam will take from 15-30 minutes.

After the Exam

• You may be asked to wait while the images are shown to the radiologist.You can discuss the results of the exam with the radiologist or your doctor.

Ultrasound vs MRI: Detecting Angiogenesis

Cancer stimulates its host tissue to form new blood vessels to support the growth of the tumor. This is called angiogenesis. Angiogenesis can be visualized by both MRI and ultrasound, providing important information about the size, shape, and location of the tumor.