Orbital positron emission tomography/computed tomography (PET/CT) imaging findings in graves ophthalmopathy

Abstract

BackgroundWe aimed to describe orbital positron emission tomography/computed tomography (PET/CT) imaging findings, both structural and metabolic, in different clinical stages of Graves ophthalmopathy (GO). This prospective, observational, cross-sectional study examined 32 eyes of 16 patients with GO.MethodsPatients were assessed with a complete ophthalmological evaluation and assigned a VISA classification for GO. All patients underwent serum thyroid hormone measurement, antibody profile, and 18-fluorodeoxyglucose positron emission tomography/computed tomography (18-FDG PET/CT) of the orbits. The 18-FDG uptake on PET images was expressed in terms of maximum standard uptake value (SUVmax). CT images were analyzed, and orbital structures were measured in millimeters. Vision, inflammation, strabismus, and overall appearance were assessed according to the VISA classification system, thyroid hormone levels, antibody values, 18-FDG uptake, and thickness of orbital structures.ResultsAltogether, 32 eyes of 16 patients (10 women, 6 men; mean age 44.31 ± 13 years, range 20–71 years) were included. Three patients were hypothyroid, seven were euthyroid, and six were hyperthyroid. CT measurements of extraocular muscle diameter were elevated (P < 0.05), and muscle 18-FDG uptake values were increased. Eyes with a clinical VISA inflammation score of ≤ 4 had an average extraocular muscle SUVmax of 3.09, and those with a score of ≥ 5 had an average SUVmax of 3.92 (P = 0.09), showing no clear correlation between clinically observed inflammation and 18-FDG uptake. 18-FDG uptake values also did not show a correlation with extraocular muscle diameter as measured by CT (R2 = 0.0755, P > 0.05).ConclusionsWe demonstrated a lack of correlation between 18-FDG extraocular muscle uptake and either clinical inflammation score or muscle diameter. Although 18-FDG uptake has been used as an inflammation marker in other pathologies, inflammation in GO may be clinically detected in PET/CT-negative cases, and cases with negative clinical findings may show inflammation on PET/CT. Clinical evaluation is mandatory but may be insufficient and inaccurate for classifying GO. A larger and homogeneous sample size and further research is needed to define the role of PET/CT in detecting, grading, and follow-up of GO to optimize treatment of the inflammatory stage respect clinical methods currently used.

18 F-FDG-PET/MRI in patients with Graves’ orbitopathy.

“…The lack of correlation between SUVmax and severity of GO is in line with prior publications on this topic: García-Rojas et al analyzed the 18 F-FDG-PET/CT scans of 16 patients with GO and found that FDG uptake in the EOM as assessed by SUVmax was significantly higher than in the non-affected control group [22]. However, a subsequent study by the same group did not find any correlation between SUVmax on the one hand and muscle thickness and clinical inflammation score on the other hand [33]. Similarly, a study by Uslu-Beşli et al showed that 18 F-FDG uptake as assessed by SUVmax was elevated in patients with GO when compared to a nonaffected control group but they as well did not find a correlation between SUVmax and muscle thickness [34].…”

Non-invasive multimodal imaging of Diabetic Retinopathy: A survey on treatment methods and Nanotheranostics

“…are used in ophthalmology and other applications [89]. The non-invasive imaging and optical modalities such as bioluminescence, reflectance, magnetic resonance spectroscopy imaging (MRSI), positron emission tomography (PET), and contrast-enhanced perfusion MRI have their intrinsic limitations for the investigation of ocular and tumor-related neovascularization [90][91][92][93][94][95]. The human eye, by nature, promotes the sub-cellular mediated resolution and non-invasive in vivo imaging of the retina and its vascularization in healthy and diseased states (retinal tumor, DR, uveitis, etc.).…”

Ocular Biodistribution Studies Using Molecular Imaging

“…This modality has not been widely used in the field of clinical ophthalmology to date [25], although its use is promising for the diagnosis of primary ocular tumours and for neurophysiologic studies [26,27,28,29,30]. In recent years, it has emerged in the research field as an essential tool for the study of the pharmacokinetics of different ophthalmic formulations, since it provides images of the drug’s biodistribution and/or its effect on the eye.…”