The value of adding 99mTc- sestamibi MBT to the current clinical standard of DBT plus 2D digital mammography (MM) was assessed. Images were acquired using a dual modality tomosynthesis (DMT) scanner designed to obtain superimposable DBT and MBT images. Seventy-five subjects with 83 biopsied lesions were scanned prior to biopsy. A blinded MQSA-certified breast radiologist with limited nuclear medicine (NM) experience viewed the images in the following sequence: 1) DBT alone, 2) add MM, and 3) add MBT (equivalent to DMT+MM). MM images were from each subject’s most recent clinical mammographic exam. At each stage, all findings were scored using a 5-point suspicion scale ranging from 1=definitely benign, to 5=definitely malignant. Independently, a blinded, experienced NM radiologist scored all MBT scans without access to the DBT or MM images, using the same suspicion scale. The NM results were provided to the breast radiologist reader following their 3-stage evaluation, and a fourth suspicion score was recorded for all findings. Using location-confirmed biopsy results as ground truth, ROC curves and the areas under the curves, Az were generated for each of the four stages, and for MBT alone. Compared to DBT+MM, the changes in Az for MBT alone, DBT, and DMT+MM were +21.4% (p<0.02), -22.1% (p<0.01), +25.2% (p<0.002), respectively. Addition of the NM report to DMT+MM had no measurable effect on ROC shape or Az value. These results suggest that hybrid tomosynthesis can potentially improve DBT diagnostic performance; that breast radiologists with limited nuclear medicine experience might nevertheless effectively utilize MBT information; and that stand-alone MBT could be a valuable complementary tomographic modality.