Abstract
Purpose: :
To compare 18-fluorodeoxiglucose (FDG) uptake by Positron Emission Tomography (PET) in extraocular muscles of patients with Graves Ophthalmopathy (GO) versus patients without GO.
Methods: :
We prospectively included patients older than 18 years of age with GO and at least 6 months without anti-inflammatory medication and patients who underwent FDG-PET with another indication, without orbital pathology and anti-inflammatory medication. FDG-PET imaging study was done to everyone, maximum Standarized Unit Value (SUVmax) was quantified in extraocular muscles (medial, superior, lateral and inferior rectus, and superior oblique) and averaged. Standard deviation (SD) and significant statistical difference (P < 0.05) were calculated with SPSS v.17 software.
Results: :
32 eyes of 16 patients of the GO group were included, 10 women and 6 men, with a mean age of 44.31 ± 13 (20-71) years. 70 eyes of 35 patients of the group without GO were included, 18 women and 17 men, with a mean age of 49.20 ± 14.36 (24-77) years. Values of muscle FDG uptake by PET were compared. Extraocular muscle average uptake of the GO group was 3.38 ± 1.31 SUVmax, while extraocular muscle average of the group without GO was 1.89 ± 0.51 SUVmax (P < 0.05).
Conclusions: :
FDG-PET has been used as an imaging tool for detecting and localizing increased metabolism and inflammation in other pathologies. GO has been studied with several clinical and paraclinical tools to detect, localize and quantify inflammation without successful results. This study suggests that FDG uptake is significantly increased in extraocular muscles of patients with GO. PET gives valuable functional information and may be a helpful tool in detecting, localizing and quantifying GO inflammation. Further research is needed to define the role of PET in detecting, grading, and follow up of GO in order to optimize treatment in the inflammatory stage, before disfiguring and dysfunctional anatomic changes occur.
Keywords: extraocular muscles: structure • imaging/image analysis: clinical • inflammation