[68Ga] Ga-DOTA-FAPI-04 And [18F] FDG PET / CT For Diagnosis of Metastatic Lesions In Patients With Recurrent Papillary Thyroid Carcinoma

Abstract

\n Context: PET CT imaging methods based on fibroblast activation protein inhibitors (FAPIs) have recently demonstrated promising clinical results. Objective: We aimed to evaluate the use of 68Ga-FAPI PET / CT and 18FDG PET / CT imaging techniques to detect the metastatic foci in recurrent papillary thyroid carcinoma.Design and Patients: This is a prospective study. Patients who were diagnosed with papillary thyroid carcinoma, achieved biochemical recovery after the first operation and having recurrence for papillary thyroid carcinoma on the follow up were included in the study. [68Ga] Ga-DOTA-FAPI-04 and [18F] FDG PET / CT were performed for comparative purpose and detection of recurrence localization.Results: [18F] FDG PET / CT detected the metastatic foci in 21 of 29 patients (72.4%), [68Ga] Ga-DOTA-FAPI-04 was able to detect the metastatic foci in 25 of 29 patients (86.2%). When the two imaging techniques were used together, the metastatic foci in 27 of the 29 patients could be detected (93.1%.). Also between the [18F] FDG PET / CT SUVmax values and [68Ga] Ga-DOTA-FAPI-04 SUVmax values, a statistical significance was found in favor of 68Ga-FAPI PET (p = 0,002).Conclusion: In conclusion, 68Ga-FAPI PET imaging technique can be used as an alternative method to detect the metastatic focus or foci in patients with recurrent papillary thyroid carcinoma. It can also increase the chance of metastatic focus or foci detection when used in conjunction with the 18 FDG PET.