Imaging Investigation of Thyroid Eye Disease

Introduction: Thyroid eye disease (TED), is a term referring to the extrathyroidal manifestation of Grave's disease, a disorder which is currently the most common cause of hyperthyroidism and is characterised by underlying autoimmunity. The pathogenic course of the disease can be broadly classified into two stages, an early inflammatory and a late fibrotic stage. These stages are reflected in clinical severity and activity classifications, such as Clinical Activity Score and Class 0: No signs or symptoms, 1: Only signs, no symptoms (e. g. lid retraction), 2: Soft tissue involvement, 3: Proptosis, 4: Extraocular muscle involvement, 5: Corneal involvement, 6: Sight loss (NOSPECS). Classifications based on the latter, have important implications in treatment decisions since patients in the early active stage of the disease are more likely to respond to anti-inflammatory and immunosuppressive therapies, whereas patients in the late fibrotic stage require different therapeutic approaches, including rehabilitative surgery. Methods: We reviewed cases of TED investigated with CT and Magnetic Resonance Imaging (MRI) in our department. We assessed the findings of imaging studies and their role in the clinical investigation of patients with TED as well as in the differential diagnosis from other disorders. Results: Imaging has a significant role in the investigation of TED, however a consensus on the use of different imaging modalities in the course of disease has yet to be reached. Nevertheless, imaging and specifically CT and MRI can have a vital role in the initial diagnosis of clinically atypical presentation of TED, in surgical planning, as well as in the differential diagnosis from other orbital disorders. Conclusion: In this review, we attempt to present current trends in imaging investigation of TED. Rather than focusing on the findings of each imaging modality separately, we present the two main imaging modalities focusing on CT and MRI, in the context of pathogenic stages of the disease.