Impact of diagnostic workup resulting from a positive low-dose molecular breast imaging scan in a screening environment

2301 Objectives Molecular Breast Imaging (MBI) has been shown to have a high sensitivity and specificity for the detection of breast cancer in women with dense breast tissue on their mammogram. MBI may demonstrate positive findings in patients with negative mammographic and ultrasonic findings, requiring final confirmation with another modality such as contrast enhanced breast MRI. The aim of this study was to ascertain the consequences of a positive MBI on the need for secondary diagnostic exams and breast biopsy. Methods A total of 373 patients with mammographically dense breasts presenting for a screening mammogram underwent low-dose MBI with 8 mCi Tc-99m sestamibi as part of a research protocol. Screening mammography was performed within 21 days of and interpreted in conjunction with the MBI. MBI studies were assigned an uptake score of 3 (probably benign), 4 (suspicious) or 5 (highly suspicious) which paralleled BIRADs assessments. Subsequent workup comprised of diagnostic mammography, ultrasound, MRI, and/or biopsy was performed as necessary to resolve MBI findings. An assessment was made of the percentage of patients returning for diagnostic workup. Results Of the 373 patients, a total of 33 (8.8%) were called back for additional work-up based on positive MBI findings. The findings in 16/33 patients (48%) were resolved by correlation with a diagnostic mammogram and ultrasound. Ultrasound alone provided resolution for 1/33 (3%) patients. Ultrasound-guided biopsy was necessary to resolve 11/33 (33%) cases. Findings in an additional 5/32 patients (15%) required diagnostic evaluation by MRI with 4/33 (12%) needing MRI guided biopsy to resolve findings. Conclusions In patients with positive MBI scans, 15% required MRI evaluation and 12% required MRI-guided biopsy, both of which are technically challenging and costly procedures. Hence the development of an MBI-guided biopsy device could clearly be beneficial in resolving positive MBI findings. Research Support Komen for a Cure and the Mayo Foundation