Positron emission tomography-computed tomography evaluation for recurrent differentiated thyroid carcinoma

Recurrence is observed in 15-20% of patients under surveillance following treatment of differentiated thyroid cancer (DTC). However, due to cell dedifferentiation, the recurrence may be iodine-negative, thereby compromising detection. For this reason, new methods of exploration are indispensable to enable localization of such recurrences. The purpose of this work is to review the contribution of positron emission tomography-computed tomography (PET-CT) in the exploration of iodine-negative recurrent DTC.

A comprehensive review and discussion of the medical literature was carried out.

Depending on the report, the sensitivity of PET-CT ranged from 70% to 85%, with up to 90% specificity. However, the large number of false negatives, which can reach 40%, is the disadvantage of this examination. PET-CT results lead to change in the therapeutic strategy in approximately 50% of patients with isolated raised serum thyroglobulin levels, and surgical exploration of a precise anatomical area in the neck.

As post-treatment recurrence of a DTC can affect patient survival, a thorough diagnostic work-up is required in these cases. Where thyroglobulin levels are elevated with no uptake on 131-iodine scans, PET-CT can be a useful complementary exploration, especially for localizing the site of recurrence.