ABSTRACT

After treatment, including total thyroidectomy, radioiodine remnant ablation, and thyroid hormone suppressive therapy, the follow-up of TC includes various tests. One has to consider that 50% of local recurrences appear in the first years but that distant metastases may occur after several years, sometimes decades, after initial therapy. Recombinant thyroid stimulating hormone (rhTSH) stimulated thyroglobulin (Tg) is the basis of following up TC. For the

localization of recurrences and metastases, several imaging methods are available today. Ultrasonography (US) is the method of choice for the detection of local recurrences and cervical lymph node metastases, 131I whole-body scintigraphy (131IWBS) for iodine-positive, and [18F] FDG-PET or PET-computed tomography (CT) for iodinenegative metastases. If [18F]FDG-PET or PET-CT is not available, whole-body scintigraphy and single photon emission computed tomography (SPECT) using nonspecific tumor searching tracers such as [99mT]sestamibi or [99mTc]tetrofosmin are alternatives. These tracers fall between 131I and [18F] FDG as they may demonstrate iodinepositive as well as iodine-negative metastases in some cases.