The role of thyroid scintigraphy with Tc-99m in the era of FNAC and molecular markers

    In Cyprus with known iodine deficiency, thyroid nodules are found in ~15% of the adults. Recent investigations show that approximately 10% of them are malignant, mainly diagnosed with FNAC. The use of thyroid scintigraphy in the work-up of thyroid nodules has been dramatically decreased during last years. It is only used in cases with low TSH level. Consequently autonomous functioning thyroid nodules (AFNT) with normal TSH are rarely diagnosed and the number of unnecessary performed FNAC on these lesions is unknown.

    We investigate the prevalence of AFTN with normal TSH level.
    Between 01.01.2011 and 31.12.2018, 1505 nuclear scans were performed, in two groups.
    In the first group we performed 1220 thyroid scan with Tc-99m to investigate the behavior of 2000 nodules found on ultrasound. In the second group, of 285 patients with hyperparathyroidism a dual tracer scan with Sestamibi and Tc-99m was performed. We used the Pertechnetate scan to investigate the behavior of 90 incidentally found nodules on ultrasound.

    On the first group we demonstrated AFNT in 30% of the cases. On the second group AFNT was found in 20/90 (22%).

    Thyroid scan using Tc-99m is able to pick up the AFNT especially in multinodular goiters. The  Tc-99m used in the dual tracer technique is a successful method to evaluate the presence of AFNT. In patients with thyroid nodules and normal TSH level to avoid unnecessary FNAC, a thyroid scan must be performed, especially in regions with iodine deficiency.


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