F-18 Fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) and Tc-99m Pertechnate Scan Findings of a Patient With Unilateral Subacute Thyroiditis

Abstract

A 57-year-old man visited the clinic with myalgia and neck pain. The patient complained of previous upper respiratory infection (URI) symptoms. Mild goiter was found on physical examination. Erythrocyte sedimentation rate (ESR) was elevated (59 mm/h). Thyroid function tests revealed an elevated free T4 (4.53 ng/dL), decreased TSH (< 0.05 uIU/mL), and normal microsomal antibody (< 25 U/mL). The patient was diagnosed with subacute thyroiditis. The whole right thyroid lobe was not visualized on the Tc-99m pertechnate thyroid scan, but the F-18 FDG PET scan showed hypermetabolism of the right lobe. During the initial phase of subacute thyroiditis, Tc-99m pertechnate scan and F-18 FDG PET can show different findings.