Orbital MRI in thyroid-associated orbitopathy

Abstract

Aim: Thyroid-associated orbitopathy (TAO) is the most common cause of proptosis in adults and the clinical picture is mostly associated with thyroid dysfunction. MRI is frequently used because of its advantages, such as high soft tissue resolution, multiple plane evaluation, and no risk of ionizing radiation exposure to the lens. The research aim was to present cases of thyroid orbitopathy with MRI findings and to compare the findings with existing literature.
 Material and Method: Patients who visited our radiology clinic with a preliminary diagnosis of TAO between April 2015 and February 2021 and underwent orbital MRIs were included in the study. We evaluated parameters such as age, sex, presence of proptosis, orbital muscle involvement, increase in orbital fatty tissue, and lacrimal gland involvement. 
 Results:A total of 35 patients were included in our study. The mean age was 40.6 (18-60) years, 19 (54%) patients were female, and 16 (46%) were male. All patients were diagnosed with Graves’ disease, whereas no patient was diagnosed with Hashimoto’s thyroiditis. The most common findings were proptosis in 33 (94%) patients, inferior rectus involvement in 27 (77%) patients, and medial rectus muscle involvement in 25 (71%) patients. No significant correlation was found between the presence of uni/bilateral involvement and TSH values (p = 0.008).
 Conclusion: In conclusion, since the presence of orbital involvement is crucial for treating thyroid diseases, all orbital structures involved should be reported by imaging. Orbital MRI is an effective imaging modality in the detection and differential diagnosis of TAO.