[⁶⁸Ga]Ga-LNC1007 versus 2-[¹⁸F]FDG in the evaluation of patients with metastatic differentiated thyroid cancer: a head-to-head comparative study

This head-to-head comparison study aimed to compare the performance of [⁶⁸Ga]Ga-FAPI-RGD (LNC1007) and 2-[¹⁸F]FDG PET/CT in the evaluation of patients with metastatic differentiated thyroid cancer (mDTC).

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 [⁶⁸Ga]Ga-LNC1007 and 2-[¹⁸F]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.

In patients with UHTg, [⁶⁸Ga]Ga-LNC1007 PET/CT detected more metastatic lymph nodes (LNs) (17 vs. 15, P = 0.317) and lung lesions (2 vs. 0) than 2-[¹⁸F]FDG. In patients with DmDTC, [⁶⁸Ga]Ga-LNC1007 PET/CT also detected more true positive lesions than 2-[¹⁸F]FDG (Total: 133 vs. 103, LN: 20 vs. 15, lung: 18 vs. 10, bone: 87 vs.73). [⁶⁸Ga]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-[¹⁸F]FDG. Specifically, the sensitivity of [⁶⁸Ga]Ga-LNC1007 PET/CT was higher than that of 2-[¹⁸F]FDG in detecting lung and bone metastases (94.7% vs. 52.6% and 100% vs. 83.9%, all P < 0.05). [⁶⁸Ga]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 [⁶⁸Ga]Ga-LNC1007 for bone metastasis was inferior to 2-[¹⁸F]FDG (15.4% vs. 88.5%, P < 0.05).

Compared with 2-[¹⁸F]FDG, [⁶⁸Ga]Ga-LNC1007 PET/CT could detect more metastatic lesions, with higher SUVmax and TBR, in patients with mDTC. [⁶⁸Ga]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