18F-FAPI-04 PET/CT in the Evaluation of Ground-glass Nodules Less Than 3 cm in Diameter Comparing to 18F-FDG PET/CT

Zhehao Lyu^1*Jianing Liu^1*Wei Han¹Shibo Guo¹Chunyu Duan¹Lili Liu²Hongyue Zhao¹Yexin Su¹Haibo Wang²Qi Zhang¹Lin Tian^1*Peng Fu^1*

• ¹First Affiliated Hospital of Harbin Medical University, Harbin, China
• ²The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang Province, China

Background: This study aimed to evaluate the clinical usefulness of fluorine 18F‑FAPI-04 PET/CT in diagnosing ground-glass nodules that are less than 3 cm in diameter in comparison with fluorine 18F-FDG PET/CT. Methods: Prospective analysis of 18F‑FAPI-04 PET/CT and 18F-FDG PET/CT scans for 74 patients with 96 GGNs less than 3 cm from 09/2021 to 10/2024 were analyzed. 18F‑FAPI-04 imaging was performed in patients with 18F-FDG PET/CT within a week. The images, parameters, and histopathological invasiveness from participants were analyzed. Tumor uptake was quantified by the maximum standard uptake value (SUVmax), standard uptake value mean (SUVmean), target-to-background ratio (TBR), and the ratio of SUVmax of the lesion to SUVmax of contralateral normal lung parenchyma (SUVindex). Results: A total of 74 patients with 96 GGNs were evaluated. Different pathological subtypes of GGNs exhibited distinct uptake values on 18F‑FAPI-04 and 18F-FDG PET/CT. The invasive pathological subtypes showed higher uptakes than noninvasive subtypes, of which 18F‑FAPI-04 PET/CT showed significantly higher uptake than 18F-FDG PET/CT in all subtypes of GGNs (all P<0.05). Notably, the optimal cut-off values for specificity of SUVmax, SUVmean, SUVindex, and TBR of 18F‑FAPI-04 PET/CT were notably higher than those of 18F-FDG PET/CT. Conclusion: 18F‑FAPI-04 PET/CT is useful for detecting GGNs, outperforming 18F-FDG PET/CT in detecting their invasiveness. It could provide valuable guidance for early-stage adenocarcinoma diagnosis, potentially impacting patient management.