COMPARISON OF F-18 FDG TO I-123 AND I-131 SCANS IN THYROID-CARCINOMA

A patient who was in remission with papillary thyroid cancer was inves tigated for recently increasing thyroglobulin levels, I-123 diagnostic whole-body imaging showed a focus of faint uptake centrally in the th yroid bed, whereas an F-18 FDG PET whole-body scan showed two foci in the right side of the neck, most likely in the cervical lymph nodes, a nd was essentially negative in the thyroid bed. An I-131 postablation scan confirmed all three neck foci, and showed an incidental pericardi al effusion. F-18 FDG PET imaging might be helpful in thyroid cancer p atients with elevated thyroglobulin levels and equivocal radioiodine s cans and may help differentiate residual tumor from a thyroid remnant.