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Mammogram is still the way to go

MRIs notice more cancer, but a lot of other things, too

MRIs notice more cancer, but a lot of other things, too

December 03, 2007|By JULIE E. GREENE

Waiting for the results of a mammogram can be a nerve-racking experience.

Waiting for the results of a biopsy even more so.

Magnetic resonance imaging (MRI) can do a better job of detecting cancer in breasts, yet mammograms are still the recommended primary screening method for breast cancer, medical officials said, because MRIs are much more expensive than a mammogram and frequently result in false readings.

The accuracy of an MRI depends on the quality of the machine - newer ones do a better job - and the experience of the radiologist, said Dr. Victor Zannis, a board member with the American Society of Breast Surgeons.

Mammograms - essentially an X-ray of the breast - detect 80 percent of breast cancers, whereas magnetic resonance imaging identifies at least 95 percent of cancers in the breast, according to Zannis and the breast surgeon society.

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"A lot of people criticize mammograms because they're only 80 percent sensitive. At least it picks up 80 percent, so it's a good screening method. But it's not perfect," said Zannis, medical director of the Breast Care Center of the Southwest in Arizona.

Mammograms are the first line of defense, said Dr. Kerri Hesley, radiologist at Women's Imaging at Robinwood Medical Center. Hesley said she would never have a woman get an MRI and not a mammogram because sometimes a mammogram will pick up things such as a tiny calcification - which can be a sign of early cancer - that an MRI wouldn't.

Breast MRIs

While MRIs will pick up more tumors and cancers than mammograms, MRIs lead to biopsies that often are negative because of false readings, Hesley said.

An MRI is used to look for contrast in the breast - for concentrated blood flow, according to Zannis and Hesley. Tumors have a higher density of blood vessels, but there are also normal reasons for blood to concentrate.

Washington County Hospital got a new MRI this summer and a computer-aided detection system in September that help eliminate a significant percentage of the previous false readings for breast cancer. But there are still enough false readings with MRIs that medical officials are reserving their use for select cases, Hesley said.

Local doctors interviewed said they reserve breast MRIs for women who have had cancer, who are at high risk of getting cancer, or whose earlier screenings show something suspicious which cannot be identified any other way.

Dr. Dona Hobart, a surgeon for Comprehensive Breast Clinic at Robinwood Medical Center, has every patient of hers with breast cancer have an MRI to determine if there are other possible cancerous areas in either breast, unless the patient cannot tolerate the MRI. The MRI machine is enclosed and the patient lies stomach down.

Another reason MRIs are not used for general screening for breast cancer is the cost. A breast MRI at Washington County Hospital costs $837 for both breasts compared with a screening mammogram, which costs $132.50 for both breasts, said Doreen Bittinger, imaging clerk for MRI and X-ray at the hospital.

"You can't justify a procedure that's that costly for screening because the majority of women don't have breast cancer," Hesley said.

Other detection methods

MRI is not the only secondary method used to screen for breast cancer or to get further imaging information. A second mammogram, one that focuses on a specific area, is one option, Hobart said. Ultrasound, which also is more expensive than a mammogram, often is used as a follow-up to a mammogram before an MRI, Hobart and Hesley said.

Digital mammography is another option for some patients, depending on its availability and whether it's recommended for the patient.

Unlike with regular mammography, also known as film mammography, a mammogram taken digitally allows the radiologist to adjust the contrast of the image to get a better look, Hesley said.

According to an American College of Radiology Imaging Network study, digital mammography was significantly better than film mammography in screening women who:

· Are younger than 50

· Have extremely dense breasts

· Are pre- or perimenopausal (had a last menstrual period within 12 months of their mammograms)

Some doctors also might try to get some ductal cells to check for precancerous cells. Dr. Stephen Carter, a breast cancer specialist with Summit Health in Franklin County, Pa., has done this with ductal lavage, and Hobart expects to have nipple aspiration available next year. (See sidebar for further information.)

Currently, nipple aspiration is like breast MRIs were a few years ago. No one's sure where it fits into the puzzle of breast cancer detection, but it is another tool, Hobart said.

Zannis said a proposed secondary screening method being researched in clinical trials but not widely available is tomosynthesis. Multiple X-rays of the breast are taken that can be viewed like CAT scan images. The breast is seen in slices, providing sharper images of the tumor.

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