Imaging in Graves' orbitopathy.

In patients with Graves' orbitopathy, magnetic resonance imaging (MRI) is a useful tool to distinguish the acute inflammatory active disease in demonstrating interstitial edema within the extraocular muscles on coronal TIRM-sequences from fibrotic, inactive endstage disease. MRI is the modality of choice to identify active inflammatory changes in order to decide on possible immunomodulatory treatment response. However, MRI should be considered in atypical cases as in asymmetrical orbital involvement, to exclude other orbital pathologies and to confirm the clinical suspicion of apical optic nerve compression in Graves' orbitopathy. Computed tomography (CT) provides precise imaging of the osseous periorbital structures and does not reveal information on the disease activity in most cases. It is therefore the method of choice to plan CT-guided orbital decompression surgery in the inactive phase of disease.