Role of orbital magnetic resonance imaging in early detection of graves’ orbitopathy and disease activity

Abstract

We aim to evaluate feasibility of using orbital diffusion tensor imaging (DTI) magnetic resonance imaging (MRI) of extraocular muscles (EOMs) in patients with Graves’ orbitopathy (GO) versus clinical activity score (CAS) in early detection of GO activity. This case control study was conducted on 20 consecutive patients (10 males, 10 females with a mean age of 35.50±13.65 years) with Graves’ orbitopathy and 10 age- and sex-matched volunteers without any thyroid abnormality as a health control (HC). The patients and HCs underwent DTI MRI of the orbit in the coronal plane. The mean diffusivity (MD) was calculated. Thyroid stimulating hormone receptor antibody (TRAb) was measured using third generation thyroid binding inhibiting immunoglobulin (TBII) with ELISA method. CAS score, according to the standardized criteria of the European Group on Graves Orbitopathy (EUGOGO), was calculated for the patients. GO patients’ EOMs showed significantly higher MD values and higher compared to HCs’ (P < 0.001). Median CAS score was 4. A statistically significant positive correlation was only detected between CAS score and inferior rectus (IR) MD (r=.360, p=.023).