T2 mapping MRI in prediction of Graves ophthalmopathy activity

Abstract

Objective To explore the value of T2 mapping MRI in predicting Graves ophthalmopathy (GO) activity. Methods 74 patients with GO and 30 normal individuals underwent coronal T2 mapping MRI were analyzed prospectively from August 2010 to June 2013 in Beijing Tongren Hospital, Capital Medical University. All the GO patients met Mourits criterion, with hyperthyroidism history, and enlargement of extraocular muscles (EOMs) found by MRI. GO patients were grouped by CAS. Of which, 52 patients in CAS ≥ 3, 22 patients in CAS<3, 12 patients in CAS=0, and 10 patients in CAS=0 or 1. T2 values of EOMs (superior rectus muscle, inferior rectus muscle, medial rectus muscle, external rectus muscle and superior oblique muscle) were calculated. The differences of mean T2 values between two eyes, among EOMs, different CAS groups and controls were evaluated by paired-sample t test and one-way ANOVA, respectively. The correlation between maxT2 and CAS was conducted by Spearman rank correlation analysis in GO patients. The cut-off value of maxT2 in predicting GO activity was determined by ROC curve. Results There was no significant difference on T2 values between sides and among EOMs in control (P>0.05), while GO group showed significant difference (P<0.05) . T2 value increased by sequence of superior oblique muscle, external rectus muscle, superior rectus muscle, medial rectus muscle and inferior rectus muscle, failed to show significant difference between medial and superior rectus muscle (P=1.00). T2 value increased by sequence of normal control, CAS=0, CAS=1/2 and CAS≥ 3 group (P<0.05) . Spearman rank correlation revealed positive correlation between maxT2 and CAS (r=0.898, P<0.01). The cut-off value of maxT2 was 138.68 msec, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 63.5% (33/52), 90.9% (20/22), 94.3% (33/35), 51.3% (20/39), 71.6% (53/74), respectively. Conclusion T2 mapping MRI is valuable in predicting GO activity. Key words: Graves ophthalmopathy; Magnetic resonance imaging