Comparison of (123)I and (131)I for whole-body imaging in thyroid cancer.
We compared the diagnostic sensitivities of (123)I and (131)I whole-body imaging in differentiated thyroid cancer.


METHODS
Twelve thyroidectomized patients (3 previously treated with (131)I) were studied. After a period of thyroid hormone withdrawal, whole-body imaging was performed approximately 24 and 72-96 h after administration of 74-185 MBq (2-5 mCi) (123)I and 111-185 MBq (3-5 mCi) (131)I, respectively.


RESULTS
Both (123)I and (131)I revealed residual thyroid tissue, present in 9 patients. (131)I detected metastases in 5 studies of 4 patients. In 4 of 5 studies, (123)I missed metastases shown by (131)I in 8 body regions including the neck, mediastinum, lungs, and bone and detected 3 other sites of metastasis only in retrospect. No lesion was better seen with (123)I than with (131)I.


CONCLUSIONS
Although (123)I is adequate for imaging residual thyroid tissue, it appears to be less sensitive than (131)I for imaging thyroid cancer metastases.
Sarkar
Salil D
SD
Division of Nuclear Medicine, Department of Radiology, Long Island Jewish Medical Center, New Hyde Park, New York, USA. salil.sarkar@gte.net
Kalapparambath
Tomy P
TP
Palestro
Christopher J
CJ
D000368:Aged; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging*
D007457:Iodine Radioisotopes