Fig. 2.

(A-C) Iodine scan-negative and fluorodeoxyglucose positron emission tomography (FDG PET)-positive metastasis. A patient with DTC had bone pain in the back after total thyroidectomy. An iodine scan was negative. By contrast, on an fluorine-18 FDG PET (F-18 FDG PET) scan, there was a focal hypermetabolic bone lesion, suggesting malignant tumors. I-124, a PET radiotracer iodine isotope, demonstrated faint iodine uptake on PET scans. This discrepancy between the I-131 scan and I-124 PET may have been caused by a difference in the resolution of the instruments. The patient underwent high-dose radioiodine treatment, and the bone pain improved. WBS, whole body scan. Adapted from Cheon, Korean J Endocr Surg 2011:11:139-45 [9].