Evaluation of the dedicated breast PET imaging technique including axillary region

3020 Introduction: Metabolic imaging of the primary breast tumor with 18F-fluorodeoxyglucose (FDG) PET may assist in predicting treatment response. Dedicated breast PET (dbPET) systems are expected to detect small breast cancers than conventional whole-body PET by targeting only one breast at a time and imaging the breast close to a small aperture, thereby enabling local imaging with high spatial resolution. On the other hand, there is a problem that blind areas may exist in areas close to the chest wall or the axillary region due to its small aperture. However, additional imaging of the axillary region may help overcome this problem. In this study, we evaluated a technique for imaging the breast and axillary region using a ring-shaped dbPET system. Materials and Methods: Ten preoperative cases of breast cancer in which FDG PET scans were performed between October and December 2020 were included in the study. After 90 minutes of FDG administration, breast scan was performed with dbPET system (SET-5002, Shimadzu) in a prone position. And the axillary regions were scanned with the arm plunged shoulder-deep into the PET detector. The acquisition time was set at 5 minutes for each region. Fused images were created by the dbPET data and the previously obtained contrast-enhanced MRI images. And the blind area of mammary region in dbPET data was evaluated per mammary gland area. Results: \nIn the case of breast scans only, the incidence of blind areas were 10%, 30%, 30%, 20%, and 100% in the Upper Outer Quadrant, Lower Inner Quadrant, Upper Outer Quadrant, Lower Outer Quadrant, and axillary regions, respectively. And, the incidence was reduced to 10%, 30%, 10%, 0%, and 10% when additional axillary scan was performed. Conclusions: In this study, we evaluated a new imaging technique using a ring-shaped dbPET system. These data indicated that additional imaging of the axillary region might be synergic and complementary for more accurate dbPET examination.