Why Breast MRI is Increasing

Breast MRI usage patterns revealed in new study

(RxWiki News) In 2012, American women had nearly 39 million mammograms, the standard breast cancer screening method. Magnetic resonance imaging (MRI) is also gaining popularity for breast cancer screening and diagnosis.

A new study found that the use of breast MRI studies nearly tripled between 2005 and 2009.

The procedure is being used most commonly for diagnostic evaluations, often following a suspicious mammogram, and for breast cancer screenings.

"Ask your doctor about breast cancer screening options."

A team of researchers, led by Karen J. Wernli, PhD, of the Group Health Research Institute in Seattle, examined the patterns of breast MRI use in community practices between 2005 and 2009.

According to American Cancer Society guidelines, breast MRI screening is appropriate for women who are at high risk for developing breast cancer because they:

  • are known to carry the BRCA gene mutation, which increases a woman’s lifetime risk of breast cancer.
  • are the first-degree relative (child, parent, sibling) of a known BRCA gene mutation carrier.
  • have a more than 20 percent lifetime risk of developing breast cancer.

MRI studies use powerful magnets, radio waves and a computer to create images of the breast. Multiple images are taken, which a computer then generates into detailed images of the breast.

A contrast dye may be used for the study. MRIs do not use ionizing radiation.

While MRI is better than mammography at finding breast abnormalities, this sensitivity leads to a higher number of false-positives — something that appears to be cancer but turns out not to be.

Breast MRI is also more expensive, costing more than $1,000 compared to about $300 for a mammogram.

For this study, Dr. Wernli and colleagues analyzed five national Breast Cancer Surveillance Consortium registries and learned that the use of breast MRIs nearly tripled between 2005 and 2009, increasing from 4.2 to 11.5 examinations per 1,000 women.

MRIs were used primarily for diagnostic evaluation (40.3 percent) or screening (31.7 percent) during the study period. A diagnostic evaluation is conducted to examine a breast symptom or as a follow-up to evaluate an abnormality found during a previous imaging study.

The rate of screening breast MRI increased more than four-fold between 2005 and 2007 from 0.8 to 3.4 per 1,000 women and then stabilized at 4.3 breast MRI examinations per 1,000 women in 2009.

Screening breast MRIs increased from 18.1 percent in 2005 to 34.5 percent in 2009.

The study also revealed that women who had breast MRI were more likely to be under the age of 50, white, childless and to have either a personal or family history of breast cancer and extremely dense breast tissue than women who had never had an MRI.

"MRI finds more cancers than mammography and ultrasound, but we do not know whether or not finding these cancers will save lives," Daniel B Kopans, MD, professor of radiology at Harvard Medical School and senior radiologist of the Breast Imaging Division at Massachusetts General Hospital, told dailyRx News.

"I have urged for many years that a randomized, controlled trial be undertaken to determine the value of MRI screening," Dr. Kopans said, "but it would be very expensive, and there has not been sufficient enthusiasm for doing a trial. It is possible that MRI screening could have a major impact on the death rate in the US, but injecting women with Gadolinium [contrast dye] each year may not be the best solution," said Dr. Kopans, who was not involved in this study.

The researchers wrote, “Our findings suggest that there is a need for improvement in the use of diagnostic and screening breast MRI for women most likely to benefit from this imaging tool.”

The authors added that “...there have been improvements in appropriate use of breast MRI, with a smaller proportion of examinations performed for further evaluation of abnormal mammogram results and symptomatic patients, and more breast MRI performed for screening of women at high risk.”

This study was published November 18 in JAMA Internal Medicine.

The National Cancer Institute supported this research.

Two of the authors reported financial relationships with GE Healthcare, Phillips Medical Systems and Bayer Healthcare, manufacturers of breast imaging technology. No other conflicts of interest were reported.

Review Date: 
November 18, 2013