[Short-tau inversion-recovery (STIR) sequence magnetic resonance imaging evaluation of orbital structures in Graves'...

To evaluate the orbital structures and to establish correlations with disease activity and severity in patients with Graves' hyperthyroidism and orbitopathy (GO) using short-tau inversion-recovery (STIR) sequence magnetic resonance imaging (MRI).

Observational, cross-sectional, case-control study. Twenty-eight patients with euthyroid status after treatment and GO (GO group) and 15 control subjects (control group) were included. Patients underwent a complete ophthalmologic examination and were then assessed according to the EUGOGO (European Group on Graves' Orbitopathy) recommendations. Muscle cross-sectional areas, orbital tissue volumes and the signal intensity ratio (SIR) from the most inflamed extraocular muscle were calculated using a STIR-T2 weighted sequence MRI. Correlations between clinical and MRI measurements were analyzed.

Enlargements in the cross-sectional areas and volumes were significant for most EOMs (P<.001), but not for the lateral rectus muscle cross-sectional area. A significant difference in SIR values between patients with GO and control subjects (P<.001) was found. No significant correlations were found between muscle cross-sectional areas, orbital tissue volumes, SIR values and the clinical activity parameters.

Given the small sample size of our study, with the obvious need for larger clinical trials, we were unable to demonstrate that the STIR sequences in MRI are a sensitive tool in assessing patients with longstanding GO in order to detect inflammatory changes and activity follow-up, possibly because it is in inactive phase. Meanwhile, it is still necessary to continue performing a thorough clinical evaluation in the therapeutic management of GO.