Measurement of the Quantitative Orbital Coronal CT in Thyroid Associated Ophthalmopathy

Objective To study the values of quantitative assessment of extraocular muscles in diagnosing the thyroid associated ophthalmopathy(TAO).Methods The maximum section area,short and long diameters of extraocular muscles on orbital coronal CT were measured and the value of R was calculated in 50 healthy persons and 50 patients with TAO.Results The maximum section areas of 228 extraocular muscles in 50 patients with TAO increased,of them,inferior rectus(30.3%) and mediate rectus muscle(23.2%) were common,followed by superior rectus,lateral rectus and superior oblique muscle.Their maximum section areas(70.21 mm2,56.93 mm2,64.06 mm2,58.51 mm2,20.65 mm2,respectively) and the values of R(0.61,0.55,0.61,0.50,0.52,respectively) were larger than that in healthy group(27.72 mm2,27.07 mm2,26.93 mm2,36.74 mm2,9.42 mm2 respectively in maximum section areas) and(0.41,0.35,0.60,0.34,0.44 in the values of R,respectively).There were statistical significant differents between them.Conclusion The quantitative coronal CT measurement,especially the values of R can assess enlargement of extraocular muscles accurately,which may be helpful in diagnosis of TAO.