Endocrine Abstracts

Introduction: F-18 FDG PET/CT has a valuable role in the initial workup for solid tumors, including lung adenocarcinoma and head and neck squamous cell carcinoma. However, its role in the staging of thyroid carcinomas remains contentious. Present guidelines advocate for the deployment of F-18 FDG PET/CT in instances of recurrence detection, particularly in patients demonstrating elevated serum thyroglobulin levels with a concurrent negative radioiodine whole body scan. Routine F-18 FDG PET for initial workup is not recommended. The present study aims to elucidate the diagnostic accuracy and prognostic implications of employing perioperative F-18 FDG PET/CT in individuals newly diagnosed with differentiated thyroid cancer (DTC).

Methods: We retrospectively analyzed perioperative F-18 FDG PET/CT scans of 49 patients with newly diagnosed DTC from January 2018 to June 2021 in our institute. The clinicopathologic and demographic characteristics were recorded. Imaging findings were compared with clinical follow-up and histopathologic results. Each patient’s status at the end of follow-up was classified according to the dynamic risk stratification.

Results: The comprehensive patient cohort exhibited a sensitivity, specificity, and diagnostic accuracy of F-18 FDG PET/CT at 90.0%, 83.3%, and 87.5%, respectively. Within the subset presenting a ATA high-risk of recurrence (n = 36), these parameters were observed at 92.9%, 87.5%, and 91.7%. Among the cohort with negative F-18 FDG PET/CT findings (n = 18), a substantial 83.3% manifested an excellent response by the end of follow-up, with none experiencing a structural-incomplete response. Conversely, of those with positive F-18 FDG PET/CT results (n = 31), merely 9.7% achieved an excellent response, whereas 77.4% were classified with a structural-incomplete response by the end of the follow-up. The risk of incomplete response was significantly elevated in patients with positive FDG PET/CT results (P < 0.0001).

Conclusions: Perioperative F-18 FDG PET/CT demonstrates both diagnostic accuracy and prognostic value in patients newly diagnosed with DTC, advocating for its consideration in the clinical decision-making process.