Is Routine Diagnostic Radioiodine Whole-Body Scintigraphy Needed in Patients who Received Ablative doses of Radioiodine for Differentiated Thyroid Carcinoma?

Abstract

Aim: The present large-series retrospective sought to assess DWBS findings 6‒12 weeks after RIAT in DTC patients in various risk groups. In addition, the study compared patients’ simultaneous sTg levels.

Material and Methods: The follow-up data of 2879 patients who had received RIAT for DTC between 1998 and 2016 were evaluated for inclusion in the study. The study retrospectively evaluated the following: age at the time of diagnosis; gender; histopathological features of thyroidectomy materials (histological subtype, variant, dimension, multi-focality, thyroid capsule, and vascular invasion of tumors); TNM stage; ATA classification; sTg, suppressed-serum Tg, and antiTg antibody levels; and DWBS findings. Patients were categorized according to sTg level (undetectable, 1‒10 ng/ml, and >10 ng/ml). Then, the DWBS findings were analyzed according to sTg level.

Results: The study analyzed 2184 patients (1805 F, 379 M; mean age: 43.54±12.64). In 2077 (95%) patients, the DWBSs performed 6‒12 months after RIAT had shown no pathological uptake throughout the entire body. Pathological uptake had been detected in the neck and outside the neck in 88 (4%) and 19 (1%) patients, respectively. All patients who had had normal DWBSs also had had undetectable simultaneous sTg levels. In addition, the DWBSs had been normal in 187 (8%) patients who had had simultaneous sTg levels> 1 ng/ml and in 286 (13%) patients who had had levels > 10 ng/ml. In all patients who had pathological uptake in DWBSs, simultaneous sTg levels were > 1ng/ml, and in 47, they were> 10 ng/ml.

Conclusion: Routine DWBS seems to be unnecessary, even in high-risk DTCs. However, in patients who have detectable levels of serum sTg, it could be performed to localize the disease and plan patient management.