Evaluation of radioiodine therapy in differentiated thyroid cancer subjects with elevated serum thyroglobulin and negative whole body scan using 131I with emphasize on the thallium scintigraphy in these subgroups

A. Zakani 1, M. Saghari 2, M. Eftekhari 1,2, A. Fard-Esfahani 2, B. Fallahi 2, J. Esmaili1, M. Assadi 3

1 Nuclear Medicine Department, Vali Asr Hospital, Faculty of Medicine, Tehran University of Medical Sciences, Tehran (Iran)
2 Research Institute for Nuclear Medicine, Shariati Hospital, Tehran University of Medical Sciences, Tehran (Iran)
3 The Persian Gulf Nuclear Medicine Research Center, Bushehr University of Medical Sciences, Bushehr (Iran)

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• Nuclear Medicine

Objective: Negative diagnostic 131I whole body scans with elevated serum thyroglobulin (Tg) levels are found in 20% of patients with differentiated thyroid cancer (DTC). Empirical radioiodine treatment has been advocated by some researchers, but has had with controversial outcomes. This anterospective study was performed to examine this dilemma and also to determine the capability of thallium (201Tl) scintigraphy in these patients.

Materials and Methods: A total of 21 patients who had a history of DTC and elevated serum Tg levels, together with a negative diagnostic 131I whole body scans (WBS), were included in the study. All patients underwent posttreatment 131I WBS. Patients with negative posttreatment 131I WBS then underwent 201Tl scintigraphy.

Results: The 21 included patients (9 women and 12 men) had a mean age of 53 ± 14.17 years. The mean pretreatment and posttreatment Tg levels were 227.23 ± 208.50 ng/ml and 163.43 ± 282.57 ng/ml, respectively (p value 0.05). In the posttreatment 131I WBS, 10 patients showed abnormal findings in their images. In a follow-up scan after 201Tl treatment, 7 out of 11 patients had positive scans.

Conclusion: The study indicates a positive effect of RAI therapy in DTC patients with elevated Tg and negative 131I WBS. In addition, 201Tl scintigraphy can be useful as an alternative modality to improve tumoral detection in this situation and when access to a PET system is limited.

Corresponding Author: Majid Assadi, MD; e-mail: assadipoya@yahoo.com, asadi@bpums.ac.ir

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