Molecular Imaging Approaches for Supplemental Screening in Women at Increased Breast Cancer Risk

Abstract

Mammography is an effective screening method that reduces breast cancer mortality (1). However, mammography is not a perfect test and its sensitivity is diminished in women with dense breast tissue (2). For women at increased breast cancer risk, the use of imaging modalities in addition to mammography, termed supplemental screening, can improve the overall cancer detection rate. Current guidelines recommend MRI for supplemental screening in women with greater than 20% lifetime risk of breast cancer (3). For women who cannot tolerate MRI, have mammographically dense breast tissue, or have an intermediate lifetime risk of breast cancer, screening ultrasound can be considered (3). However, these techniques have some drawbacks, which have fueled interest in alternative functional imaging-based methods for supplemental screening in high-risk women. In this issue of The Journal of Nuclear Medicine, Brem et al. investigate the diagnostic performance of a molecular imaging approach for supplemental breast cancer screening (4). See page 678Breast-specific g-imaging (BSGI) is a Food and Drug Administrationapproved radionuclide-based technique that can be used to detect breast cancer (5,6). A high-spatial-resolution, small-field-of-view g-camera detects and localizes g-ray energy emitted by the radiopharmaceutical 99m Tc-methoxyisobutylisonitrile (sestamibi), which preferentially accumulates in malignant breast cells with increased vascular supply and concentration of mitochondria compared with surrounding normal breast tissue. Images are acquired immediately after intravenous injection of the radiopharmaceutical, with the patient seated in standard mammographic views (craniocaudal and mediolateral oblique views) with the breast in mild compression for a total of approximately 40 min. Interpretation of breast-specific g-images follows a standardized lexicon and results in assessment categories and recommendations that parallel those of other imaging modalities outlined by the American College of Radiology Breast Imaging-Reporting and Data System (BI-RADS) (7-9).Although several studies have evaluated the performance of BSGI for diagnosing breast cancer in a heterogeneous mix of clinical indications (10), data regarding the application of BSGI for supplemental screening for women at increased breast cancer risk are sparse. The study by Brem et al. is a single-institution, retrospective review of asymptomatic, increased-risk women undergoing BSGI from 2010 to 2014 whose most recent screening mammogram showed no suspicious abnormalities (4). The study population consisted of 849 women ranging in age from 26 to 83 y with a personal history of treated breast cancer, a family history of breast cancer, a personal history of an atypical or high-risk breast biopsy result, or a known genetic predisposition to breast cancer development. BSGI detected 14 mammographically occult cancers in 849 women, resulting in a supplemental cancer detection rate of 16.5 per 1,000 women screened. Furthermore, mammographic breast density did not affe...