Positron emission tomography/computed tomography in patients treated for differentiated thyroid carcinomas

Abstract

Differentiated thyroid cancer (DTC) generally has a favorable prognosis; however, the chance of a recurrence in patients with DTC is 20%, and 8% of patients with recurrence will subsequently die of the disease. After thyroid remnant ablation, detectable serum thyroglobulin levels are a sensitive marker for residual or recurrent disease, while imaging procedures, primarily neck ultrasound and an iodine-131 (¹³¹I) or iodine-123 diagnostic whole-body scan, are useful to localize recurrent disease. However, ultrasound cannot identify lesions outside the neck, and diagnostic whole-body scan is of limited value if progressive dedifferentiation of thyroid carcinoma cells occurs. In these patients, fluorine-18 (¹⁸F)-fluorodeoxyglucose PET/computed tomography (¹⁸FDG-PET/CT) has been shown to improve detection and localization of tumor foci. Additionally, ¹⁸FDG-PET/CT is also of value in selecting patients unlikely to benefit from additional ¹³¹I therapy and those at highest risk of disease-specific mortality, which may prompt more alternative therapies. Recently, iodine-124 (¹²⁴I)-PET/CT was proved to perform better than low-dose diagnostic ¹³¹I scans. Additionally, ¹²⁴I PET/CT succesfully predicts the results of subsequent high-dose post-treatment ¹³¹I scans and allows lesion-based dosimetric calculations. The present article reviews the utility and limitations of PET/CT techniques in DTC management and offers practical recommendations.

Keywords::

• ¹⁸F-fluorodeoxyglucose
• differentiated thyroid carcinoma
• iodine-124
• positron emission tomography/computed tomography
• thyroid nodules

Financial & competing interests disclosure

The author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.