Symmetric increased skeletal muscular uptake of F-18 fluoro-deoxyglucose: A clue for the diagnosis of Graves’ disease
A 64-year-old man was subjected to a whole-body F-18 fluoro-deoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) scan for detection of primary malignancy, if any. He had history of significant loss of appetite and loss of weight for 6 months. He also complained of intermittent dysphagia and constipation. Upper gastrointestinal endoscopy showed large hiatus hernia and biopsy from the lower end of esophagus was consistent with Barret's esophagitis. His liver function test was in the normal range. There was no personal and family history of diabetes or thyroid disease. Hence, it was planned to do FDG-PET/CT in search of any neoplastic process as a cause for the patient's recent illness. Whole body FDG-PET (maximum intensity projection image) demonstrated symmetrically increased uptake of F-18 FDG in the skeletal muscles, with no other focal abnormal FDG uptake []. The uptake was much higher compared to the physiological uptake in the liver. This unusual finding raised the suspicion of Graves’ disease and the patient was investigated further.\nTc-99m pertechnetate scan showed homogeneous increased uptake (9.9%) in both lobes of the thyroid []. The thyroid hormone profile was also done and the values were: T3: 2.9 ng/mL (normal = 0.8–2.0 ng/mL); T4: 17.47 g/dL (normal = 5.1–14 g/dL) and thyroid-stimulating hormone: 0.005 μIU/mL (normal = 0.27–4.2 μIU/mL). In view of these findings, Graves’ disease was diagnosed and the patient was started on treatment with anti-thyroid drug.