Serial STIR Magnetic Resonance Imaging Correlates with Clinical Score of Activity in Thyroid Disease

Purpose: To assess the correlation between inflammatory activity in extraocular muscles measured with serial short tau inversion recovery (STIR) sequence magnetic resonance imaging (MRI) scans and clinical disease activity in thyroid eye disease.

Methods: In this retrospective study, 22 patients with thyroid eye disease who had undergone serial MRI scans using the STIR sequence were assessed. The signal intensity ratio (SIR) of the most inflamed extraocular muscle was compared with the Mourits score (a clinical measure of thyroid eye disease activity).

Results: The SIR value has previously been shown to correlate with clinical activity of thyroid eye disease. In a particular patient the SIR value increases in proportion with the clinical features of the disease as assessed by the Mourits rating system. When the change in STIR sequence MRI is compared with the change in Mourits score rating for a given patient the correlation is highly significant (p < 0.001).

Conclusions: This study confirms that serial STIR sequence MRI scans correlate with clinical disease activity. Inflammatory activity in the most inflamed muscle (as measured by SIR) reflects overall disease activity. SIR values obtained from MRI scans provide a useful measure of disease activity and may help in the monitoring and treatment of this condition.