Thyroid carcinoma: iodine-131-negative whole-body scan reverses to positive after a combination of thyrogen stimulation and withdrawal.
OBJECTIVE
Reports state that scan results for as many as 25% of patients with differentiated thyroid carcinoma will convert to iodine-131 (I-131) negative over time with positive thyroglobulin levels. Tl-201, positron emission tomography (PET), and sestamibi or tetrofosmin have all helped to identify I-131-negative thyroid carcinomas. The authors have identified a case of reversal of I-131 findings from negative to positive after short-term thyroxine withdrawal combined with treatment with recombinant human thyroid-stimulating hormone (rhTSH).


METHODS
The authors obtained multiple I-131 whole-body scans with 4-week thyroid hormone withdrawal, post-I-131 therapy scans, nonthyroid withdrawal Tl-201 chloride whole-body tumor images, and finally combined 2.5-week thyroid hormone withdrawal and rhTSH-stimulation I-131 whole-body scans before and after therapy.


RESULTS
The authors examined one patient during a period of 9 years whose I-131 whole-body scan results were at first positive and then became negative. After a combination of rhTSH stimulation and thyroid hormone withdrawal, the results changed again to I-131 positive.


CONCLUSIONS
This is the first known case in which I-131 findings changed from negative to positive. A combination of rhTSH stimulation and nearly adequate withdrawal may help convert more I-131-negative whole-body scans to positive.
Kasner
Darcy L
DL
Marshfield Medical Research and Education Foundation, Department of Radiology, Nuclear Medicine Section, Marshfield, Wisconsin, USA.
Spieth
Michael E
ME
Starkman
Marjorie E
ME
Zdor-North
Deborah
D
D018263:Adenocarcinoma, Follicular / Q000000981:diagnostic imaging / Q000556:secondary / Q000628:therapy; D002291:Carcinoma, Papillary / Q000000981:diagnostic imaging / Q000556:secondary / Q000628:therapy; D005188:False Negative Reactions; D005260:Female; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008137:Longitudinal Studies; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging* / Q000628:therapy; D018365:Neoplasm, Residual / Q000000981:diagnostic imaging; D011237:Predictive Value of Tests; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000627:therapeutic use; D011994:Recombinant Proteins / Q000008:administration & dosage; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging / Q000556:secondary; D013793:Thallium; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000628:therapy; D013972:Thyrotropin / Q000008:administration & dosage*; D013974:Thyroxine / Q000008:administration & dosage*; D014915:Whole-Body Counting
D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D011994:Recombinant Proteins; C027549:thallium chloride; D013972:Thyrotropin; D013793:Thallium; D013974:Thyroxine