Objective To evaluate the thickness and mean Young’s modulus（Emean） of four extraocular muscles in thyroid associated ophthalmopathy（TAO） by shear wave elastography（SWE）

and to explore SWE diagnostic value for TAO.Methods A random collection of 60 TAO patients hospitalized in the endocrinology department of our hospital were divided into two subgroups:38 patients in TAO edema stage（group A） and 22 patients in TAO fibrosis stage（group B）

50 healthy volunteers matching age and sex during the same period were selected as the control group.High-frequency ultrasound was used to measure the thickness of extraocular muscles

and SWE was used to measure Emean of extraocular muscles

the difference of above parameters among three groups were compared.The ROC curve was drawn

and the diagnostic efficiency of Tao was analyzed.Results The thickness and Emean value of extraocular muscles in the group A and group B were higher than those in the control group（both P<0.05）.The Emean values of the four extraocular muscles in the control group

group A

and group B gradually increased（P<0.05）

and there was no significant difference in thickness between the group A and group B.The Emean cut-off value of superior

inferior

lateral and medial rectus for diagnosing TAO were 9.85 kPa

9.65 kPa

9.85 kPa

9.65 kPa

respectively

the sensitivity were 86%

78%

82%

80%

and the specificity were 90%

95%

95%

98%.Conclusion SWE can quantitatively assess the elasticity of extraocular muscles

which provide a reference for clinical diagnosis of extraocular muscle diseases in TAO.