Prediction and early diagnosis of orbitopathy is needed in patients with Graves’ disease, especially when radioiodine therapy is planned. Positron emission tomography/computerized tomography (PET/CT) using flourine-18-fluorodeoxyglucose (FDG) is an effective imaging modality in detection of inflammation, however, its ability to detect orbital inflammation has not been well studied. The aim of our study is to determine the ability of FDG PET/CT to detect orbital inflammation related with Graves’ disease, identify active orbitopathy, predict the radioiodine-triggered orbitopathy, and find out the effects of radioiodine on orbital inflammation.
Total 31 Graves’ disease patients and 17 controls were included. All Graves’ disease patients underwent cranial FDG PET/CT imaging prior therapy. Radioiodine therapy and post-treatment PET/CT study was applied to 21 patients. PET/CT images of all examinees were evaluated, measuring extraocular muscle maximum standard uptake value (SUVmax) and muscle thickness.
FDG uptake was increased in the majority of extraocular muscles in Graves’ disease patients in comparison to controls and this increase was found to be irrelevant from muscle thickness. Extraocular muscle SUVmax values did not increase in Graves’ orbitopathy patients who received radioiodine under corticosteroid prophylaxis. SUVmax level of all orbital rectus muscles were increased after radioiodine therapy in nonsmokers, whereas no increase was detected in smokers.
FDG PET/CT may be helpful in detection of extraocular muscle inflammation and it may show ongoing orbitopathy in early stages of inflammation before anatomical changes occur.
Departments of aNuclear Medicine
bOphthalmology, Cerrahpaşa Medical Faculty, Istanbul University, Fatih/Istanbul, Turkey
Correspondence to Lebriz Uslu-Beşli, MD, Department of Nuclear Medicine, Cerrahpaşa Medical Faculty, Istanbul University, Fatih/Istanbul 34098, Turkey Tel: +90 212 414 3000; fax: +90 212 632 0050; e-mail: email@example.com
Received March 2, 2017
Received in revised form April 24, 2017
Accepted August 9, 2017