RT Journal Article
SR Electronic
T1 <sup>68</sup>Ga-FAPI PET/CT as an Alternative to <sup>18</sup>F-FDG PET/CT in the Imaging of Invasive Lobular Breast Carcinoma
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 512
OP 519
DO 10.2967/jnumed.123.266798
VO 65
IS 4
A1 Sahin, Ertan
A1 Kus, Tulay
A1 Aytekin, Alper
A1 Uzun, Evren
A1 Elboga, Umut
A1 Yilmaz, Latif
A1 Cayirli, Yusuf B.
A1 Okuyan, Merve
A1 Cimen, Vuslat
A1 Cimen, Ufuk
YR 2024
UL http://jnm.snmjournals.org/content/65/4/512.abstract
AB Accurate staging of invasive lobular carcinoma (ILC), a subtype of breast cancer, is vital for effective clinical management. Although 18F-FDG PET/CT is a commonly used tool, its efficacy varies across different histologic subtypes. To mitigate this challenge, our investigation delves into the potential utility of 68Ga-fibroblast activation protein inhibitor (FAPI) PET/CT as an alternative for staging ILC, aiming to address a significant research gap using a more expansive patient cohort than the smaller samples commonly found in the existing literature. Methods: In this retrospective analysis, women diagnosed with primary ILC of the breast underwent both 18F-FDG PET/CT and 68Ga-FAPI PET/CT. Both modalities were compared across all lesion locations with the used reference standard. The interval between scans was 1 wk, without any intervening treatments. Lesions were categorized visually, and tracer activity was analyzed using SUVmax, tumor-to-background uptake ratio, and uptake ratios. Both modalities were compared across various parameters, and statistical analysis was performed using SPSS 22.0. A P value of less than 0.05 was chosen to determine statistical significance. Results: The study included 23 female ILC patients (mean age, 51 y) with hormone-positive, human epidermal growth factor receptor type 2–negative tumors. Most (65%) had the luminal A subtype. 68Ga-FAPI PET/CT outperformed 18F-FDG PET/CT, with higher tumoral activity and tumor-to-background uptake ratios (P &lt; 0.001). Primary tumors showed significantly increased uptake with 68Ga-FAPI PET/CT (P &lt; 0.001), detecting additional foci, including multicentric cancer. Axillary lymph node metastases were more frequent and had higher uptake values with 68Ga-FAPI PET/CT (P = 0.012). Moreover, 68Ga-FAPI PET/CT identified more lesions, including bone and liver metastases. Pathologic features did not significantly correlate with imaging modalities, but a positive correlation was observed between peritumoral lymphocyte ratio and 68Ga-FAPI PET/CT–to–18F-FDG PET/CT uptake ratios (P = 0.026). Conclusion: This study underscores 68Ga-FAPI PET/CT’s superiority over 18F-FDG PET/CT for ILC. 68Ga-FAPI PET/CT excels in detecting primary breast masses, axillary lymph nodes, and distant metastases; can complement 18F-FDG PET/CT in ILC; and holds potential as an alternative imaging method in future studies.