68Ga-FAPI Versus 18F-FDG PET/CT in Evaluating Newly Diagnosed Breast Cancer Patients

Purpose This study aimed to compare the performance of 68 Ga-FAPI and 18 F-FDG PET/CT in the evaluation of patients with newly diagnosed breast cancer. Methods Thirty-four women with newly diagnosed breast cancer who underwent both 68 Ga-FAPI and 18 F-FDG PET/CT within 1 week were prospectively included in the study. The imaging characteristics of primary lesions, diagnostic efficiency of lymph node metastasis (LNM), and accuracy of N stage evaluation between 2 PET/CTs were compared. Results 68 Ga-FAPI showed higher SUV max (11.06 ± 5.48 vs 8.33 ± 6.07, P = 0.02) and tumor-to-background ratio (15.32 ± 10.33 vs 8.25 ± 5.51, P < 0.001) than 18 F-FDG in primary tumors. 68 Ga-FAPI SUV max was positively correlated with the pathological grade of the primary lesions and the final stage of the patients ( P < 0.001). The specificity and accuracy of 68 Ga-FAPI was higher than that of 18 F-FDG in the diagnosis of LNMs on patient-based and lesion-based analysis ( P < 0.001). The accuracy for the evaluation of N stage and N0 axillar status was 91.2% (31/34) and 85.7% (12/14) for 68 Ga-FAPI, and 73.5% (25/34) and 42.9% (6/14) for 18 F-FDG, respectively. Conclusions The 68 Ga-FAPI SUV max was positively correlated with the pathological grade of the primary lesions and the final stage of the patients. 68 Ga-FAPI PET/CT has higher accuracy than 18 F-FDG in the evaluation of N stage, especially N0 axillar status, which is helpful to improve the treatment strategy for breast cancer patients.