Mammography Gets a Helping Hand
Helps detect tumor activity in dense breasts
WEDNESDAY, July 3, 2002 (HealthDayNews) -- A portable device that peers into the biochemical machinery of cells can help identify breast cancers that conventional scanning can't find.
A new study has found the machine, called a high-resolution breast-specific gamma camera (HRBGC), gives doctors a view into an organ's biochemical percolation. Cancer cells are busier than normal tissue, and the scanning device is able to detect this activity.
Experts say the tool, which has already been approved by the U.S. Food and Drug Administration, isn't meant to replace mammography. Rather, it will supplement that technology in women with dense breasts and other tissue traits that cloud a clean mammogram.
"Because it's small, you can bring it much closer to the patient with any angle you want," says Dr. Cahid Civelek, a Johns Hopkins University nuclear medicine specialist and co-author of the study, which appears this month in the Journal of Nuclear Medicine. "The way it's built, it can see smaller objects more clearly."
More than 180,000 American women will be diagnosed with breast cancer this year, according to the National Cancer Institute. Routine mammography is recommended for women over 40.
Conventional X-ray mammography works very well for most women. However, for the quarter of women with dense breasts, the scan's ability to find tumors drops markedly, and as many as 30 percent to 35 percent of tumors go undetected.
While mammography can identify lesions, it's poor at discerning benign masses from cancers. As a result, only about 20 percent to 25 percent of lumps found during mammograms are malignant.
Scientists have been working on a variety of ways to improve the eyesight and accuracy of mammography. One promising approach has been the gamma camera. This device, which has been around in various forms for decades, offers doctors an inside look at an organ's biology by detecting a radioactive contrast agent that's absorbed more readily by tumor cells than healthy tissue.
However, this technique, called scintimammography, has limitations. The machines are bulky, resolution is sometimes poor, and they have trouble catching lumps of a centimeter or less in diameter.
The new device, made by Dilon Technologies, is a modified gamma camera designed specifically to scan breast tissue. For an imaging agent it uses a radioactive molecule attached to a breast cancer drug that migrates to tumors and gets taken up by the cells.
Civelek and his colleagues tested the machine on 50 women with 55 breast lesions that had already been discovered by a manual exam or during mammography or ultrasound scanning. Subsequent cell samples showed that 52 percent of the lesions were benign and 48 percent were cancerous.
Both machines were able to identify the benign lesions 93 percent of the time. However, the high-resolution device identified nearly 79 percent of the cancerous tumors, compared with 64 percent for the conventional gamma camera.
The new device was also more effective at diagnosing tumors that couldn't be felt, and at finding lumps a centimeter or smaller in diameter. It also detected four masses, with an average size of just 8.5 millimeters, which the other gamma camera missed.
Lon Slane, president of Dilon Technologies, which sponsored the research, says the company has received federal approval to market its new 6800 gamma camera and has already sold one of the devices to a hospital. The machines cost about $179,000 apiece, falling between the price of standard X-ray mammography scanners and their more advanced digital siblings.
Slane says the high-resolution gamma camera ideally will supplement mammograms and ultrasound scans with vague results. The most likely candidates for the additional test are women with dense breasts -- who include the young and those taking hormone replacement therapy -- as well as those with scars from previous biopsies. "An X-ray simply can't penetrate the breast, and you get a cloudy, washed-out picture," Slane says.
Another advantage of the machine is that the test, which takes 20 minutes to perform, is painless. "During the imaging procedure, the breast is not compressed as in mammography, and therefore there is no discomfort to the patient," he says.
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