Imaging of Differentiated Thyroid Cancer with Iodine-124 and F-18-FDG

Positron emission tomography (PET) is an established imaging device in oncological clinical setting using several isotope-labeled compounds of which I-124 and F-18-labeled fluorodeoxyglucose (FDG) are the most relevant ones for imaging of patients with differentiated thyroid cancer (DTC). Whereas I-124 PET is applied to identify thyroid cancer cells expressing the sodium-iodine symporter (NIS) which is correlated to a well-differentiated phenotype, F-18-FDG PET reveals thyroid cancer cells with a higher level of dedifferentiated feature with a more aggressive phenotype. Besides imaging NIS, I-124 PET enables a dosimetry approach to calculate radiation doses delivered to target lesions. In this chapter, we discuss the role of these two imaging techniques in thyroid cancer patients.