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A Journal on Nuclear Medicine and Molecular Imaging
Affiliated to the and to the International Research Group of Immunoscintigraphy
Indexed/Abstracted in: Current Contents/Clinical Medicine, EMBASE, PubMed/MEDLINE, Science Citation Index (SciSearch), Scopus
Impact Factor 2,413
Online ISSN 1827-1936
ADVANCES IN PET - PART II
Salvatore B. 1, 2, Paone G. 2, Klain M. 2, Storto G. 3, Nicolai E. 1, D’Amico D. 1, Della Morte A. M. 1, Pace L. 2, 3, Salvatore M. 2, 3
1 Fondazione SDN, Naples, Italy
2 Department of Biomorphological and Functional Sciences Federico II University, Naples, Italy
3 Institute of Biostructures and Bioimages National Council of Research, Naples, Italy
Aim. The aim of this study was to evaluate the role of 18F fluorodeoxyglucose-positron emission tomography (FDG-PET), differentiated thyroid cancer and thyroglobulin in patients with differentiated thyroid carcinoma (DTC) treated with therapeutic 131I because of elevated thyroglobulin (Tg) levels during follow-up. The results of FDG-PET/CT were compared with post-therapy 131I whole-body scan (131I-t-WBS) and Tg at short-term follow-up.
Methods. Forty-five patients with DTC underwent a new therapeutic 131I administration based upon Tg values >1.5 ng/mL. All patients underwent 131I-t-WBS 5-7 days after 131I therapy. A few days before 131I administration, a FDG-PET/CT scan was performed in all patients. FDG-PET/CT was considered positive (PET+) when at least one abnormal focus of FDG uptake was found; likewise, 131I-t-WBS was considered positive (WBS+) when at least one abnormal focus of uptake was found. Assessment of short-term response to radioiodine was performed by measuring Tg values.
Results. FDG-PET/CT was positive in 32 patients, 23 of which had a positive 131I-t-WBS, and negative in 13, 8 of which had a negative 131I-t-WBS. Overall agreement was 69%. Tg values were significantly higher in FDG-PET/CT positive (502±1 027 ng/mL) than in FDG-PET/CT negative patients (57±94 ng/mL). A significant difference emerged between 131I-t-WBS positive (561±1 086 ng/mL) and 131I-t-WBS negative (65±120 ng/mL) findings. In these 45 patients, Tg normalized in 36%, was reduced by at least 50% in 24%, and remained unchanged in the remaining 40%. Overall, at short-term follow-up, Tg values normalized in 77% of the 13 patients with negative FDG-PET/CT and in 19% of the 32 patients with positive FDG-PET/CT.
Conclusion. FDG-PET/CT is a powerful and useful tool for assessing patients with DTC. It can provide additional information in those patients with high Tg at follow-up and eligible for 131I therapy. A negative FDG-PET/CT could also represent a prognostic tool combined with serum Tg testing at short term follow-up.
language: English, Italian