Objective: Thyroid cancer is increasing in incidence. Prostate-specific membrane antigen (PSMA) targeted radionuclide imaging and treatment demonstrated remarkable value in prostate cancer patients. Studies have shown that PSMA is also expressed in thyroid cancer. Our purpose is to evaluate the clinical usefulness of [68Ga]Ga-PSMA-11 PET/CT for the diagnosis of thyroid cancer.
Methods: We enrolled 23 DTC and 17 RAIR-DTC patients prospectively. All patients underwent [68Ga]Ga-PSMA-11 PET/CT and 2-[18F]FDG PET/CT. PSMA expression was determined by immunohistochemistry on histological samples of lymphatic metastasis of 12 patients. We compared the detection rates and semi-quantitative parameters between [68Ga]Ga-PSMA-11PET/CT and 2-[18F]FDG PET/CT.
Results: A total of 72 lesions were detected. Detection rates of DTC and RAIR-DTC by [68Ga]Ga-PSMA-11 PET/CT were lower than those by 2-[18F]FDG PET/CT (60.00% vs 90.00%, p = 0.004; 59.38% vs 96.88%). Compared with DTC, RAIR-DTC had higher semi-quantitative parameters of 2-[18F]FDG PET/CT. There was no significant difference in semi-quantitative parameters of [68Ga]Ga-PSMA-11 PET/CT between DTC and RAIR-DTC. Immunohistochemistry showed a significantly higher PSMA expression for RAIR-DTC than for DTC. However, there was no significant correlation between PSMA expression and SUVmax on 68Ga-PSMA [68Ga]Ga-PSMA-11 PET/CT.
Conclusions: [68Ga]Ga-PSMA-11 PET/CT can detect thyroid cancer metastases but its detection rate was lower than that of 2-[18F]FDG PET/CT. There was a difference in PSMA expression levels between DTC and RAIR-DTC, but the difference was not reflected on [68Ga]Ga-PSMA-11 PET/CT.
Advances in knowledge: [68Ga]Ga-PSMA-11 PET/CT has potential value in the diagnosis of thyroid cancer. [68Ga]Ga-PSMA-11 PET/CT could screen out patients who may benefit from PSMA targeted radionuclide therapy.