A study on orbit changes in Graves disease using CT

Objective To study characteristics of orbit changes in Graves disease using CT, and to evaluate clinical value of CT in diagnosis of Graves ophthalmopathy. Method 200 orbits in 100 patients with Graves disease were retrospectively reviewed with CT imaging data. Intensity and size of extraocular muscles and position of the globe were measured on CT images and were compared with normal ranges and clinical data as well. Results 61 (61%) patients had at least one enlarged extraocular muscle, 17 (17%) had decreased intensity of extraocular muscle and the muscle was infiltrated by fat. 56 (56%) had exophthalmos. 75 (75%) had exophthalmos and/or abnormalities in extraocular muscle. 75 (75%) were diagnosed as Graves ophthalmopathy using CT, and 69 (69%) were diagnosed as such using other clinical methods. A collective usage of CT and other clinical methods can improve preciseness of diagnosis as high as 84%. Conclusion Graves ophthalmopathy, in CT imaging, is characterized by enlargement but low intensity of extraocular muscles, exophthalmos, anterior shifting and enlargement of lacrimal gland, widening of superior ophthalmic vein. The followings may be helpful in diagnosing Graves ophthalmopathy as: quantitative CT scan of orbit, size and intensity of ex- traocular muscles and position of the globe.