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Breast CT More Comfortable, May Detect Tumors Better
Than Mammography
Testing moves forward to find better way to detect
breast cancer
Dec. 2, 2005 - Breast CT, an investigational
technology for early breast cancer detection, may be better than
mammography at detecting breast lesions and is much more comfortable for
women, researchers from the University of California, Davis reported
today at the annual meeting of the Radiological Society of North America
in Chicago. It is hoped a less stressful method for early detection of
breast cancer will encourage more women to have regular testing.
"In this initial evaluation, breast CT images were
subjectively found to be equivalent to and potentially better than
standard mammography for the detection and evaluation of breast cancer,"
reported Karen Lindfors, professor of radiology at UC Davis School of
Medicine and Medical Center.
Lindfors presented preliminary results from the
first 21 patients enrolled in an ongoing Phase II trial of a breast CT
prototype developed at UC Davis. The trial is designed to determine if
breast CT can detect lesions as effectively as mammography. Researchers
will evaluate about 190 patients in all. Women in the trial all have
mammograms that are suspicious or highly suspicious for cancer and
warrant a needle biopsy.
Prior to the needle biopsy, each volunteer
undergoes breast CT. Lindfors and her colleagues then compare the breast
CT studies with the mammograms and pathology reports. The comparison is
subjective and nonblinded.
At the radiological society meeting, Lindfors
reported that lesions seen on mammography were also seen on breast CT in
19 of the first 21 cases. The two lesions not seen on breast CT were
both benign. One of the two benign lesions was in a very large breast;
the other was a low-density lesion.
Lindfors noted that breast CT modifications now in
progress may improve the prototype machine's ability to scan very large
breasts and to detect lower-density abnormalities.
"Initial impressions were favorable with respect to
breast CT," she said. "However, it is apparent that refinements in
patient positioning and improvements in viewing techniques and
radiologist training will be required to optimally generate and
interpret the breast CT image data."
If the current trial confirms that breast CT does
as well as mammography, the next step will be a larger trial comparing
the two technologies head to head. UC Davis researchers hope to show
that breast CT can detect smaller tumors than mammography.
Patients in the current Phase II trial are also
asked to compare the comfort of breast CT and mammography. The first 21
patients gave breast CT an average score of 8. (A score of one indicates
breast CT is "much worse" than mammography and 10 indicates breast CT is
"much more comfortable.")
A mammogram is an X-ray taken through all the
layers of the breast at once. The breast CT prototype developed at UC
Davis takes images of virtual "slices" of the breast -- about 300 images
per breast. Computers then assemble these images into highly detailed,
three-dimensional pictures. Unlike mammography, in which the breast is
squeezed between two plates, the breast CT requires no breast
compression. The patient lies face down on a padded table. The table has
a circular opening in it, through which the patient places one breast at
a time. A CT machine under the table rotates around each breast.
Scanning takes about 17 seconds per breast.
The breast CT was developed by UC Davis radiology
professor John Boone in collaboration with Lindfors, J. Anthony Seibert,
also a radiology professor at UC Davis, and Thomas R. Nelson, a
radiology professor at UC San Diego. The project was funded by $6
million in grants from the California Breast Cancer Research Program,
the National Cancer Institute and the National Institute for Biomedical
Imaging and Bioengineering.
Computed tomography is used every day to scan
brains, lungs, abdomens and pelvises. But imaging experts long ago
dismissed CT as impractical for breast cancer screening, assuming it
would require too much radiation.
Boone, a medical physicist who holds six scientific
patents, decided to revisit the issue, recognizing that radiation-dose
estimates for breast CT were based on use of standard CT machines, which
would require the breast and entire chest to be scanned together. When
Boone recalculated radiation doses based on scanning the breast alone,
he found that CT imaging would use no more radiation than mammography.
UC Davis Cancer Center is the only National Cancer
Institute-designated cancer center serving the Central Valley and inland
Northern California, a region of 5 million people. The UC Davis Cancer
Research Program is made up of 180 scientists on three campuses: the UC
Davis Medical Center campus in Sacramento, the UC Davis main campus in
Davis, Calif., and the Lawrence Livermore National Laboratory in
Livermore, Calif.
Video news release
(Windows Media Player file, best viewed with a PC)
For a larger pdf document of the graphic messages
in this story -
click here.
For a larger version in a computer graphic -
click here.
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