[Ga]Ga-LNC1007 versus 2-[F]FDG in the evaluation of patients with metastatic differentiated thyroid cancer: a head-to-head comparative study.

Purpose: This head-to-head comparison study aimed to compare the performance of [Ga]Ga-FAPI-RGD (LNC1007) and 2-[F]FDG PET/CT in the evaluation of patients with metastatic differentiated thyroid cancer (mDTC).

Methods: Ten unexplained hyperthyroglobulinemia (UHTg) patients and 20 patients with definite metastatic lesions of thyroid cancer (DmDTC) were enrolled in the study. All patients underwent both [Ga]Ga-LNC1007 and 2-[F]FDG PET/CT within 1 week. The final diagnosis was based on histopathological results and a comprehensive evaluation of laboratory tests and multimodal imaging characteristics.

Results: In patients with UHTg, [Ga]Ga-LNC1007 PET/CT detected more metastatic lymph nodes (LNs) (17 vs. 15, P = 0.317) and lung lesions (2 vs. 0) than 2-[F]FDG. In patients with DmDTC, [Ga]Ga-LNC1007 PET/CT also detected more true positive lesions than 2-[F]FDG (Total: 133 vs. 103, LN: 20 vs. 15, lung: 18 vs. 10, bone: 87 vs.73). [Ga]Ga-LNC1007 PET/CT demonstrated significantly higher SUVmax (Total: 6.30 vs. 3.84, LN: 8.28 vs. 4.82, Lung: 3.31 vs. 1.49, Bone: 5.73 vs. 3.87, all P < 0.05) and TBR (Total: 6.92 vs. 4.93, LN: 6.48 vs. 4.16, Lung: 5.16 vs. 2.57, Bone: 7.22 vs. 5.41, all P < 0.05) in true positive lesions compared to 2-[F]FDG. Specifically, the sensitivity of [Ga]Ga-LNC1007 PET/CT was higher than that of 2-[F]FDG in detecting lung and bone metastases (94.7% vs. 52.6% and 100% vs. 83.9%, all P < 0.05). [Ga]Ga-LNC1007 PET/CT exhibited better specificity and accuracy in diagnosing LNs (96.9% vs. 66.7% and 96.3% vs. 68.5%, all P < 0.05). However, the specificity of [Ga]Ga-LNC1007 for bone metastasis was inferior to 2-[F]FDG (15.4% vs. 88.5%, P < 0.05).

Conclusion: Compared with 2-[F]FDG, [Ga]Ga-LNC1007 PET/CT could detect more metastatic lesions, with higher SUVmax and TBR, in patients with mDTC. [Ga]Ga-LNC1007 had better accuracy in the diagnosis of LN and lung metastasis. Trial registration ClinicalTrials.gov NCT05515783. Registered 01 May 2022. URL of registry https://classic.

Clinicaltrials: gov/ct2/show/NCT05515783.