Inclusion Criteria:  Patient is 18 years or older. Signed Informed Consent. Subject is diagnosed with a histologically confirmed differentiated thyroid carcinoma, that is considered RAI refractory. There is evidence of persisting or recurrent disease, based on serum thyroglobulin levels and/or medical imaging. Subject should have a routine clinical 18F-FDG PET/CT performed within two months prior to the study scan. Female patients should be either post-menopausal, surgically sterile, or using highly effective contraceptives (methods that can achieve a failure rate of less than 1%: combined hormonal contraception, progestogen-only hormonal contraception associated with inhibition of ovulation, intrauterine device, intrauterine hormone-releasing system, bilateral tubal occlusion, vasectomized partner, sexual abstinence).  Exclusion Criteria:  Patient has a known other active malignancy. Subject is potentially pregnant (urinary test can be performed in case of doubt) or breastfeeding. Patient is mentally or legally incapacitated.