Molecular breast imaging for breast cancer screening in myocardial perfusion patients

Objectives Molecular breast imaging (MBI) performed with a dedicated dual-head CZT gamma camera, has demonstrated 3x the sensitivity and equivalent specificity to screening mammography in women with both dense breasts and increased risk of breast cancer. In this study we evaluated MBI in a cohort of women at average risk. MBI was offered as an additional test to women scheduled to undergo a stress myocardial perfusion imaging (MPI) study since both tests utilize ^99mTc-sestamibi.

Methods Patients undergoing MPI are required to wait 40 min following a stress injection of ^99mTc-sestamibi. MBI was performed during this waiting period, incurring no additional exam time or radiation dose to the patient. Bilateral CC and MLO views were acquired at 3 min/view. Patients were required to have had a mammogram performed within the past year. A radiologist interpreted the MBI studies and any suspicious findings were reviewed with the mammogram. A combination of pathology/clinical findings within a 15-month follow-up period will be used to establish sensitivity and specificity.

Results Currently, 71 women (of an eventual 1200) presenting for MPI underwent MBI. MBI detected 2 breast tumors in 2 patients (9 mm and 8 mm invasive ductal carcinomas) and 2 false positive lesions in one patient (papilloma and atypia). The remaining 68 patients had negative or benign findings on MBI. In 3 patients, benign lesions were detected on MBI, which did not require further follow up after comparison with mammographic findings.

Conclusions MBI may be a valuable additional test for detecting breast cancer in women undergoing MPI. Although true sensitivity and specificity will be established at 15 months follow-up, early results suggest that MBI will have a very high specificity in the average-risk population.