Efficacy of 18F‐fluorodeoxyglucose PET/CT for Detecting Lymph Node Metastasis in Papillary Thyroid Carcinoma

Abstract

ObjectiveTo evaluate the efficacy of preoperative 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) for detecting cervical lymph node (LN) metastasis in papillary thyroid carcinoma (PTC).Study DesignCase series with chart review.SettingUniversity tertiary care facility.Subjects and MethodsWe retrospectively compared the pathologic results for 409 cervical LN levels in 140 patients who underwent thyroidectomy and central neck dissection with/without lateral neck dissection with the findings of preoperative PET/CT, ultrasonography (US), and CT. We judged LN metastasis in PET/CT using the maximum standardized uptake value (SUVmax) at the optimal cutoff value in receiver operating characteristic curves and compared the sensitivity, specificity, and diagnostic accuracy of the 3 imaging tools.ResultsAt all neck levels (central and lateral compartments), PET/CT had a sensitivity of 57.5%, specificity of 68.6%, and diagnostic accuracy of 63.6% when the cutoff value of SUVmax was 1.125. The corresponding values were 59.1%, 90.6%, and 76.3%, respectively, for US and 53.8%, 91.9%, and 74.6% for CT. In the central compartment (level VI), sensitivity, specificity, and diagnostic accuracy were 48.9%, 67.4%, and 59.9% for PET/CT (cutoff SUVmax 1.125); 47.8%, 96.3%, and 76.7% for US; and 41.3%, 97.0%, and 74.4% for CT, respectively. In the lateral compartment (levels II-V), the corresponding values of sensitivity, specificity, and diagnostic accuracy were 70.2%, 69.3%, and 69.8% for PET/CT (cutoff SUVmax 1.055); 70.2%, 81.8%, and 75.8% for US; and 65.9%, 84.1%, and 74.7% for CT.ConclusionPET/CT is less effective as a preoperative diagnostic tool for detecting cervical lymph node metastasis in PTC than US or CT.