68Ga-DOTA-FAPI-04 PET/CT imaging in radioiodine-refractory differentiated thyroid cancer (RR-DTC) patients.

Abstract

This study aimed to assess the potential of 68Ga-DOTA-FAPI-04 PET/CT for the detection of the radioiodine-refractory differentiated thyroid cancer (RR-DTC) lesions. We analyzed the 68Ga-DOTA-FAPI-04 PET/CT imaging data of 24 RR-DTC patients (7 men and 17 women; 49.6 ± 10.5 year). Clinical data were collected including history, last post-therapeutic radioiodine whole body scan, contemporary CT, thyroglobulin, and antithyroglobulin. Target lesions were selected and measured by the RECIST 1.1. The mean growth rates of the target lesions in the past 6months were recorded. Tumor uptake of lesions were quantified by SUVmax and the tumor-to-background ratios. The correlation between SUVmax and target lesion growth rate and thyroglobulin was analyzed. On patient-based analysis, positive metastases were detected in 87.5% (21/24) patients. Except for the lymph node (LN) metastasis of 3 patients (patient 6, 12 and 17#) and the lung metastasis of another 3 patients (patient 9, 13 and 21#), most of the lesions were positive on 68Ga-DOTA-FAPI-04 PET/CT images, including LN metastasis and distant metastasis such as lung, bone and pleura. There were altogether 33 target lesions including 30 lung metastases and 3LN metastases with the mean SUVmax and the growth rate were 4.25 and 6.51%, respectively. SUVmax was statistically associated with the growth rates of the target lesions (p = 0.047). No statistically significant correlation was found between the SUVmax and the serum thyroglobulin levels (p = 0.139). 68Ga-DOTA-FAPI-04 PET/CT has a promising detection rate for RR-DTC metastasis. The FAPI uptake of the tumor may provide a potential therapeutic target for RR-DTC. NIH Clinical Trials.gov (NCT04499365).