View 2019 Abstracts

The Clinical Activity Score (CAS) is widely used to grade activity of Graves’ Orbitopathy (GO) and guide treatment decisions but has a number of limitations. Non-echoplanar diffusion-weighted magnetic resonance imaging (non-EPI-DWI) of the extra-ocular muscles (EOMs) may be able to address some of the limitations posed by CAS and other imaging techniques but the correlation with CAS is unknown.

A retrospective study of 31/88 patients seen in a multidisciplinary GO clinic over a 5 year period who had at least one ophthalmic and endocrine assessment including CAS score and non-EPI-DWI Apparent Diffusion Coefficient (ADC) calculation. Spearman’s rank correlation coefficient was used to determine the relationship between CAS and non-EPI-DWI. A Decision Tree was constructed to evaluate clinical decision-making and Receiver-Operator Curves (ROC) were generated for mild GO and dysthyroid optic neuropathy (DON).

In total, 60 non-EPI-DWI scans (368 EOMs) were evaluated. There was a significant positive correlation between CAS and ADC (rs=0.403 CI 0.312-0.489, P<0.0001). ADC values were significantly higher in the CAS ≥3 group compared to the CAS <3 group, P<0.0001. Our Decision Tree identified a third ‘intermediate’ severity cohort where non-EPI-DWI was particularly useful in guiding clinical decisions. ADC performed well as a diagnostic test in predicting DON (AUC 0.974 95% CI 0.93-1.0).

Non-EPI-DWI correlates well with CAS in our patients and was a useful adjunct to CAS in making clinical decisions especially in patients with ‘intermediate’ severity GO and may also be useful in identifying patients at risk of DON.