PT  - JOURNAL ARTICLE
AU  - Salil D. Sarkar
AU  - Tomy P. Kalapparambath
AU  - Christopher J. Palestro
TI  - Comparison of <sup>123</sup>I and <sup>131</sup>I for Whole-Body Imaging in Thyroid Cancer
DP  - 2002 May 01
TA  - Journal of Nuclear Medicine
PG  - 632--634
VI  - 43
IP  - 5
4099  - http://jnm.snmjournals.org/content/43/5/632.short
4100  - http://jnm.snmjournals.org/content/43/5/632.full
SO  - J Nucl Med2002 May 01; 43
AB  - We compared the diagnostic sensitivities of 123I and 131I whole-body imaging in differentiated thyroid cancer. Methods: Twelve thyroidectomized patients (3 previously treated with 131I) 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) 123I and 111–185 MBq (3–5 mCi) 131I, respectively. Results: Both 123I and 131I revealed residual thyroid tissue, present in 9 patients. 131I detected metastases in 5 studies of 4 patients. In 4 of 5 studies, 123I missed metastases shown by 131I 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 123I than with 131I. Conclusion: Although 123I is adequate for imaging residual thyroid tissue, it appears to be less sensitive than 131I for imaging thyroid cancer metastases.