ST. LOUIS — To the patient, it looks like a regular mammography machine. It works like a regular mammography machine. Unfortunately for some, it still feels like a regular mammography machine. But digital mammograms are beginning to replace traditional film mammograms at major hospitals and imaging centers.

“One reason is that they are better for dense breasts,’’ says Dr. Harley Hammerman, a radiologist who is chief executive at five Metro Imaging Centers in the area. All five have digital mammography.

With conventional mammography, X-rays pass through the breast tissue and blacken an X-ray film. The radiologist takes those images, has them developed, places them on a lighted wall and reads them. With digital mammography, the X-rays hit a special sensor, which records the image electronically. Radiologists can then manipulate the image on their computer.

“We’re still using X-rays and looking at the same kinds of images,’’ says Dr. Kimberly Wiele, assistant professor of radiology at Washington University and a radiologist at the Breast Health Center at Siteman Cancer Center, which switched in the fall to all digital mammograms. “But instead of a view box on film, we’re looking at a computer screen. The major difference is that we can manipulate the images using computer-type controls. We can zoom in and check something. Another advantage is in terms of when we get it. We don’t have to wait for a technologist to develop the film and wait for it to process.’’

It does, however, take the radiologist more time to manipulate the image and read it.

Mammograms have been used successfully for more than 35 years to diagnose breast cancers. A major limitation to film mammography is the film itself. Once it is obtained, it cannot be altered, so if it’s underexposed, for example, the contrast is lost and can’t be regained.

A study from the National Cancer Institute in 2005 showed that, for most women, digital and film mammography had similar screening accuracy. But the study found digital mammography to be significantly better in younger women and women with dense breasts (generally breast density decreases over time, but estrogen replacement therapy, menopause and weight gain or loss can change a woman’s breast density).

This is important because younger women are often affected by more invasive cancers.

Another bonus is 40-50 percent less radiation, he says.

For Joyce Niehaus, 52, of St. Louis, digital mammography is the only way to go.

“The whole process is much quicker,’’ she says. Niehaus was diagnosed with breast cancer seven years ago, so every trip to get a mammogram is an agonizing experience.

One of the things Metro Imaging is trying to do is to make that trip less agonizing. That means a quicker visit with digital mammography and on-site diagnosis, a new concept at the center.

“I can’t tell you how fabulous it is to get the results right away ... whatever they can do to alleviate my anxiety,’’ Niehaus says.

Hammerman also notes that, instead of having to courier over the physical images to the patient’s doctor as with film mammography, digital mammography allows the radiologist to send the images to the doctor via computer.

“Or if I want one of my partners to look at something, I can send the image to them, and they can give me an opinion on the spot,’’ Hammerman says. “It gives us flexibility.’’

He can also manipulate the screen to zoom in on a particular spot. Sometimes he does that because he sees something that concerns him; sometimes the computer highlights a suspect place.

“We are dealing with real data, not a photographic image,’’ Hammerman says.

Though the cost of the equipment is expensive, which prohibits some hospitals in the area from switching to them, the cost to the consumer is the same. Most insurance companies pay for a digital mammogram the same way they pay for a regular one.

Sometimes, radiologists use magnetic resonance imaging or ultrasound in addition to mammograms to screen for breast cancer.

A study published in the New England Journal of Medicine in 2004 showed that MRIs may find breast cancer better than mammograms in high-risk women.

The MRI is very sensitive, meaning it can see a lesion well, but it can’t say that what it’s seeing is breast cancer. Hammerman says that means you often find trouble spots (often false-positives) that warrant a biopsy.

However, for high-risk women, such as those with a genetic abnormality, MRIs are recommended in addition to mammography.

Ultrasounds are sometimes ordered so the doctor can get a different look at the breast.

“Ultrasound uses a sound beam to get an image,’’ Wiele says. “It’s not the same kind of information (as you get from a mammogram). You look at tissue interfaces, the texture of solid masses and shapes, and whether they are solid or cystic.’’

“Some tumors show up better or mammography, some on ultrasound; it all has to do with what’s around it.’’

(c) 2007, St. Louis Post-Dispatch.

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