The role of 18F-Fluorodeoxyglucose Positron Emission Tomography in patients with suspected recurrence or metastatic differentiated thyroid carcinoma with elevated serum thyroglobulin and negative I-131 whole body scan

摘要

Normal 0 21 false false false MicrosoftInternetExplorer4 BACKGROUND: The aim of this study is to evaluate the role of 18 F-FDG PET/CT in the detection of recurrence or distant metastasis in patients with differentiated thyroid carcinoma (DTC) with elevated serum thyroglobulin (Tg) and negative 131 I whole-body scan. MATERIAL AND METHODS: The study included 19 patients (13 female, 6 male, average age 64 years) with DTC after total thyroidectomy and 131 I ablation therapy that had elevated stimulated Tg and negative whole-body radioiodine scan. In all patients, standard imaging methods showed no suspicious changes. 18 F-FDG PET/CT was performed after TSH stimulation with rhTSH or withdrawal of thyroid hormone. An evaluation of the dependence of the result of 18 F-FDG PET/CT on the stimulated Tg levels was made accordingly. The statistical analysis was performed using Kruskal-Wallis test and ROC curves. RESULTS: Based on the results of the study 18 F-FDG PET/CT in 6 patients, the suspicion of metastasis involved: the cervical lymph nodes (3 patients, ~16%) and lungs (3 patients, ~16%). The patients underwent surgery. The histopathology confirmed metastatic thyroid cancer in all cases. High levels of TSH-stimulated Tg (Tg from 32 to >300 ng/ml, median of 59.7 ng/ml) in patients were reported. The group of remaining 13 patients (~68%) with negative 18F-FDG PET/CT had low levels of TSH-stimulated Tg (Tg of from 1.76 to 10.2 ng/ml, median of 4.0 ng/ml). A particular correlation was observed between 18 F-FDG PET positivity and stimulated Tg levels. The receiver operating characteristic curve (ROC) analysis demonstrated a stimulated Tg cut-off of 28.5 ng/ml with 100% sensitivity and specificity. Stimulated Tg has a large and statistically significant (p 28.5 ng/ml, the sensitivity of the study reaches 100%.