A Case with ⁶⁸Ga-FAPI Positive and ¹⁸F-FDG Negative Breast Cancer

A female patient diagnosed of infiltrative breast carcinoma using tru-cut biopsy underwent ¹⁸flourine-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) for staging. The tumor was located in the superior external quadrant of the right breast, and did not exhibit pathological uptake in ¹⁸F-FDG PET/CT. Later, gallium-⁶⁸ (⁶⁸Ga) fibroblast activation protein-specific inhibitor (FAPI)-04 PET/CT imaging was performed and the primary tumor showed intense radiotracer accumulation. This presumes that ⁶⁸Ga-FAPI PET/CT imaging is superior to ¹⁸F-FDG imaging in detecting the primary tumor in breast cancer, thereby suggesting the replacement of FAPI by ¹⁸F-FDG in breast-cancer staging in the future.