3D molecular breast imaging using a high-resolution dedicated cardiac SPECT camera

High-resolution dedicated cardiac SPECT systems with CZT detectors have a great potential to provide 3D molecular breast imaging of sub-cm tumors. In this study, we investigated the feasibility of breast imaging using a dedicated cardiac SPECT system (GE Discovery 530c/570c) by simulating different lesion sizes, positions, and contrasts. Noise-free NCAT phantom data with ^99mTc-tetrofosmin were simulated. The lesions diameter was 5 mm, 8 mm and 10 mm, respectively, located at the center and chest wall of both left and right breasts. Various lesion contrast levels ranging between 5:1 and 40:1 were simulated. A realistic hybrid simulation was achieved by combining the projections of a simulated 8 mm lesion and the projections of the normal left breast of a ^99mTc-Sestamibi myocardial perfusion SPECT patient at supine position. For most lesion contrasts, 10 mm-diameter and 8 mmdiameter lesions can be detected visually. However, 5 mm lesions can only be detected with high contrasts. Lesions located in the right breast were better visualized than the ones located in the left breast due to the impacts from the adjacent organs with high activity, such as the heart and liver. Lesions at the center of the breast had higher contrast than the lesions at the chest wall, which were closer to high activity organs. Higher number of iterations in the reconstruction led to improved tumor contrast, at the expense of increased non-uniformity in the background. In the hybrid simulation, the 8-mm lesion was detected clearly at the center of the breast with realistic tracer distribution in the background. The preliminary results suggest that it may be feasible to detect sub-cm breast tumors located at both central breast and chest wall using the dedicated cardiac SPECT system investigated.