PEM not hindered by breast density, hormonal status: indicated for women with breast cancer.(NEWS)

CHICAGO -- Positron emission mammography appears not to be adversely affected by either breast density or a woman's hormonal status--two common limitations in mammography and breast MRI.

In a prospective, single-site study of 208 women with confirmed breast cancer, positron emission mammography (PEM) was significantly more sensitive (93%) than whole-body PET (68%) in detecting index malignant lesions, and equivalent to breast MRI (93%). Of the 182 lesions detected, PEM successfully identified 90% of the 30 ductal carcinoma in situ (DCIS) cases versus 83% detected by MRI, and 93% of the 137 invasive cancers versus 95% by MRI. In 158 cases, cancer was completely removed on core biopsy.

PEM was particularly impressive at detecting small invasive lesions, identifying all four T la lesions (5 mm or less), compared with three of four lesions detected with MRI principal investigator Dr. Kathy Schilling and colleagues reported at the annual meeting of the Radiological Society of North America.

"The trend is for PEM to detect cancer before MRI," she told reporters at a press briefing.

PEM also had fewer false positives than MRI, although the difference in specificity between the two modalities did not reach statistical significance in either ipsilateral or contralateral lesions, Dr. Schilling reported.

PEM specificity was 74% vs. 48% for MRI in the ipsilateral breast and 82% vs. 67% with MRI in the contralateral breast. Accuracy was higher with PEM in both the ipsilateral (91% vs. 78%) and contralateral (83% vs. 70%) breasts.

PEM scans were not affected by breast density or hormonal status, said Dr. Schilling, director of breast imaging and intervention at the Center for Breast Care at Boca Raton (Fla.) Community Hospital Mammographic sensitivity is reduced in dense breasts, while the specificity of breast MRI is dependent on the woman's hormonal status at the time of imaging.