18FDG-positron emission tomography/computed tomography (PET/CT) scanning in thyroid nodules with nondiagnostic cytology

Objective To assess the role of positron emission tomography/computed tomography (PET/CT) scans with ¹⁸FDG (¹⁸FDG‐PET/CT) in the evaluation of thyroid nodules with nondiagnostic cytology. Subjects and methods Eighty‐eight patients with a single euthyroid nodule and repeatedly nondiagnostic ultrasound‐guided fine‐needle cytology (US‐FNC) were enrolled in the present study. Nodules concentrating ¹⁸FDG were considered positive (i.e. suspicious for malignancy). Histological findings were obtained after surgery in all patients. Results None of 41 patients with negative ¹⁸FDG‐PET/CT scan had a final histological diagnosis of malignancy (i.e. no false‐negative results). Twenty‐nine patients with final histological diagnosis of thyroid cancer had positive ¹⁸FDG‐PET/CT scan. Eighteen patients with final histological diagnosis of benign lesions (including four with follicular adenomas) also had positive ¹⁸FDG‐PET/CT scans. The sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) were 100%, 69%, 79%, 62% and 100%, respectively. Conclusions A negative ¹⁸FDG‐PET/CT scan accurately excludes malignancy in thyroid nodules with non‐diagnostic US‐FNC procedures. Histology is still necessary to distinguish benign from malignant disease in ¹⁸FDG‐PET/CT‐positive nodules, but unnecessary surgery could have been reduced from 88 to 41 cases (46%) in our series.