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Positron Emission Mammography May Reduce False-Positive Reports: Presented at RSNA

By Ed Susman

CHICAGO -- December 3, 2008 -- Use of positron emission mammography (PEM) provides greater specificity than magnetic resonance imaging (MRI) for women undergoing diagnostic examinations for breast cancer.

"We believe that with use of positron emission mammography fewer women will be called back for additional tests and biopsies, which is emotionally traumatic for the patient as well as the family," said Kathy Schilling, MD, Center for Breast Care, Boca Raton Community Hospital, Boca Raton, Florida.

Dr. Schilling and colleagues conducted a study of 182 women with breast cancer who underwent both PEM and breast MRI. She discussed the results in a presentation on December 2 here at the Radiological Society of North America (RSNA) 94th Annual Meeting.

Although both techniques proved 89% accurate at spotting breast cancer, PEM correctly detected 90% of women with ductal carcinoma in situ, while MRI was only accurate in 83% of such cases. PEM spotted all 4 of small invasive tumours (<5 mm in diameter), while MRI found 3 of those potentially dangerous tumours.

Dr. Schilling said the key finding was that PEM gave false-positive results in 18% of women compared with 33% rate with MRI.

Because of the small number of women tested for this study, the differences in results failed to achieve statistical significance, Dr. Schilling said. However, she noted that the likelihood is that the difference will become statistically significant as the technique is tested further.

She also said that PEM is not affected by either breast density or hormonal status, conditions which can impact the ability to successfully read an MRI scan. "Unless breast MRI is performed on days 7 through 14 of the menstrual cycle, reading images is extremely difficult," Dr. Schilling said. "With PEM, we don't have that problem."

The new technique also offers relief from the enclosed, claustrophobic feel of the MRI device in which a patient is rolled into the tube-like structure of a conventional MRI. Dr. Schilling said that during PEM a woman sits upright and has freedom to move around a bit.

She pointed out that PEM has been approved for use in some women with breast cancer to see if their cancer has spread or if their treatment is working. If the findings of the new study can be replicated in larger trials, "it will be a new item in our toolbox for screening high-risk women for cancer," said Dr. Schilling.

The PEM device used in the study was developed by Naviscan PET Systems. Dr. Schilling disclosed that she has financial relationships with the company.

[Presentation title: Effect of Breast Density, Menopausal Status, and Hormone Use in High Resolution Positron Emission Mammography. Abstract VB31-04]

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