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Breast-Specific Gamma Imaging Similar to MRI in Breast Cancer Detection: Presented at ASBD

By Crystal Phend

LAS VEGAS, N.V. -- May 1, 2006 -- Breast-specific gamma imaging (BSGI) appears to have a specificity and sensitivity in finding breast cancer similar to that of magnetic resonance imaging (MRI), according to results of a pilot study presented here at the American Society of Breast Disease (ASBD) annual meeting.

Breast-specific gamma imaging is similar to other gamma imaging technologies in that it analyzes the metabolism of cancer lesions by radioisotope, but "it's a better camera basically," said lead author Costanza Cocilovo, MD, breast fellow, Beth Israel Medical Center, New York, New York, United States, in a presentation April 28^th.

In the prospective study, 163 women at high risk of breast cancer or with newly diagnosed breast cancer underwent the imaging scan. It served as an additional screening modality for those without cancer and to determine disease extents in those already diagnosed with cancer (20%). About half of the patients overall were pre-menopausal.

Overall, the researchers found that BSGI had 88.6% sensitivity, 85.7% specificity, a 69.6% positive predictive value and a 95.3% negative predictive value, which was in the range of MRI, Dr. Cocilovo said.

Another group working with gamma imaging previously reported higher sensitivity and specificity possibly due to more experience with the technology, Dr. Cocilovo said, which highlights the steep learning curve associated with this technique.

In Dr. Cocilovo's study, BSGI findings agreed with prior imaging studies or pathology or both in 82% of the patients. Nine patients had abnormalities spotted with BSGI that were not visible with other imaging studies (5.5%): 2 papillomas, 1 spindle cell tumor, 1 lobular carcinoma in situ, 2 infiltrating lobular carcinomas, 2 invasive ductal carcinomas and 1 adenocarcinoma.

Another 10.4% of patients had abnormalities seen with gamma imaging that were found to be benign, although 2 of the 17 were cleared with additional film.

Nearly 20% of patients had a change in management due to BSGI findings. About twice as many of these were pre-menopausal than were post-menopausal.

The false positive rate of BSGI in the study was 3.1%.

"Like MRI, [BSGI] has a low false negative rate but a very high sensitivity, which leads to a significant number of biopsies of benign disease," Dr. Cocilovo said. "Future studies will be needed to continue to define the role of this new technology in the diagnosis of breast disease."

Also like MRI, the quality of BSGI is affected by the woman's menstrual cycle. However, it is less expensive than MRI.

Interestingly, none of the false negatives were lobular carcinoma, "so it looks like it might be better for lobular cancer," Dr. Cocilovo said.


[Presentation title: Breast Specific Gamma Imaging: A Clinical Pilot Study. Poster 1-12]

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