The image usually shows low, but some, absorption of the sestamibi throughout the breast. In areas of cancer, the amount of drug absorption is significantly increased by the cancer. Although some benign conditions such as fibroadenomas will occasionally absorb the drug, creating a false-positive result, the researchers believe that the error rate is less than the approximately 10 percent rate found with traditional mammography.

The research team used this innovative dual-head gamma camera system to scan 100 patients who had suspicious breast lesions that were small, with a diameter of 2 centimeters (four-fifths of an inch) or less. Eighty-two cancers were later identified at surgery in 54 patients. The gamma camera detected 76 of the cancers, giving it a 93 percent success rate in these cases. Some were missed, either because the breast was not properly positioned in the device or because they were too small to detect with this technology (2 to 4 millimeters or about one-tenth to fifteen-one hundreths of an inch), says Dr. O'Connor. Still, the gamma camera was 88 percent accurate in picking up cancers less than 10 millimeters.
The researchers will also discuss preliminary findings from an ongoing, blinded clinical trial comparing the gamma camera with mammography in 2,000 women who have come to Mayo Clinic for routine screening. In the first 250 patients, the gamma camera detected four cancers, and three of these were not visible on a mammogram.


"Although these initial results are very exciting, we clearly need to image more patients to confirm the promise of the device," says Dr. Rhodes. She says the team hopes to complete the ongoing trial in the next two years.

Other Mayo researchers involved in these studies include Carrie Hruska and Dana Whaley, M.D. Their collaborators included Ira Blevis, Ph.D., from GE Healthcare, Haifa, Israel; and Douglas Wagenaar, Ph.D., from Gamma Medica - Ideas, Northridge, Calif.

For more information about Breast Diagnostic Clinics at Mayo's locations in Arizona, Florida and Minnesota, visit www.mayoclinic.org. To read more about Mayo's women's cancer research, see http://cancercenter.mayo.

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