The discomfort of a mammogram can drive some women to avoid the valuable screening, occasionally with dire consequences. Now a new procedure, dedicated breast computed tomography (CT), promises to take the pain out of breast cancer detection.
In the cone beam breast CT scanner, which was first developed at the University of California, Davis, a woman lies face down on a special table with one breast suspended through an opening. A CT scanner rotates around the breast, collecting data that are reconstructed into a three-dimensional image. The total dose of radiation is the same as in a conventional mammogram.
Since 2004, the UC Davis researchers, led by John M. Boone, Professor and Vice Chair of Radiology and Professor of Biomedical Engineering, have scanned 160 women with their prototype scanner. In early 2008, the researchers began operating a second prototype device, into which the researchers have incorporated a positron emission tomography (PET) scanner. The PET scanner tracks the metabolic activity of a tumor, if present, so the hybrid CT/PET breast scanner would allow clinicians to, among other uses, precisely localize and monitor the response of a tumor to chemotherapy, determine the extent (or staging) of tumors, and help guide radiologists conducting biopsies.
The clinical trials show that the scanner "is better mammography for mass detection," Boone says, while "offering improved comfort to the patient and a better three-dimensional understanding of pathological lesions when they are present." The scanner, however, is less efficient than regular mammography at detecting the tiny clusters of calcium (or microcalcifications) that can sometimes signal breast cancer. This is because it uses X rays at higher energies than do mammograms, reducing the contrast of the images and the ability to distinguish the calcium clusters. "Thus, we are not making the claim that breast CT is "better" than mammography-yet," Boone says.
The research was described in the talk, "Dedicated Breast CT Imaging of the Breast," presented July 29, 2008 at the 50th annual meeting of the American Association of Physicists in Medicine.
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