Graves’ ophthalmopathy (GO) is a chronic inflammatory autoimmune disease of periorbital tissue, conjunctiva and retrobulbar structures, especially involving extraocular muscles (EOM). The clinical course is characterized by two phases:  the “active phase”, which hystologically shows mononuclear cell infiltration, fibroblasts proliferation and oedema within the extra-ocular muscles, lachrymal glands and orbital adipose tissue, and the “inactive phase”, in which fibrosis predominates^1-4.

In patients with a clinical suspect of GO, it is mandatory to identify the disease phase and severity in order to establish the correct treatment^1,5.

The clinical activity score (CAS), proposed by Mourits et al.⁶, is a validated scoring system for the identification of disease phase, based on the assessment of inflammatory signs and symptoms to discriminate the disease activity.

The CAS system shows a high predictive value for the outcome of immunosuppressive treatment in GO patients, but is an examiner-dependent method, and its use for monitoring changes in clinical manifestations is debated^2,5,7,8. Some Authors pointed out that there is no exact correspondence between CAS alone and the real clinical condition of GO⁶, so that the clinical score should be integrated by imaging studies to improve the diagnostic accuracy.

In particular, MR imaging has been widely reported to detect oedema and consequently distinguish active from inactive phase of GO.

The mandatory sequences in the MR protocol include coronal fast spin echo T1-w and T2-w TIRM in axial and coronal planes, with 3 mm slice thickness 13; post-contrast T1-w images, associated with fat saturation, have been widely used to detect enhancement of the extraocular muscles or the eyelid^3,4,9, however, the convenience of performing an MR acquisition with gadolinium-based contrast administration or not in the evaluation of Graves's ophtalmopaty onset is still debated⁵.

The purpose of this retrospective study was therefore to verify the correlation between MR and clinical and laboratory data in GO at its clinical onset and during follow-up, by comparing pre-contrast and post-contrast sequences, to evaluate the role of post-contrast acquisition in the MR protocol and to propose a global MR index which best correlates with clinical activity measured by CAS and severity score.