Clinical applications of 124I-PET/CT in patients with differentiated thyroid cancer.

(124)I-PET/CT has a high clinical potential in patients with differentiated thyroid cancer (DTC). Two aspects deserve special mention: staging of recurrent or residual disease and pretherapy dosimetry. Used in combination (124)I-PET and CT allows foci of highly specific (124)I uptake to be localized with a low radiation dose, which is specifically important in pretherapy diagnostics. In addition in the combination of FDG-PET and CT non-iodine-avid lesions may be detected and may be discriminated from simultaneously occurring iodine-positive lesions. In clinical applications, the pretherapy (124)I-PET dosimetry may result in a significant alteration in the therapeutic procedure compared to standard therapy using fixed therapeutic activities. In this context, (124)I-PET dosimetry is a useful procedure especially in advanced DTC, and allows the administration of safer and more effective radioiodine activities as well as earlier multimodal interventions compared to standard empirical protocols. This review summarizes the clinical data on (124)I-PET/CT in patients with DTC, and addresses future prospects.