Purpose: To evaluate the changes of orbital tissue volumes and proptosis after methylprednisolone pulse therapy in thyroid-associated ophthalmopathy (TAO).
Methods: The cross-sectional areas of orbital tissues and proptosis were measured with magnetic resonance imaging in 40 orbits of 20 patients with TAO before and after methylprednisolone pulse therapy. The volumes of the whole orbit, orbital fatty tissue, and extraocular muscles were calculated. The volumes and proptosis were compared before and after treatment using a paired t test.
Results: Before treatment, the mean volumes were 33.0 ± 4.8 cm(3) in the whole orbit, 19.9 ± 4.1 cm(3) in the orbital fatty tissue, and 4.6 ± 1.2 cm(3) in the total extraocular muscles. After treatment, the mean volumes were 32.5 ± 4.4 cm(3) in the whole orbit, 19.9 ± 3.7 cm(3) in the orbital fatty tissue, and 4.0 ± 1.0 cm(3) in the total extraocular muscles. The mean volumes of the whole orbit (P = 0.17) and orbital fatty tissue (P = 0.82) were not significantly decreased after treatment, while the mean volume of total extraocular muscles was significantly decreased (P < 0.001). The mean proptosis value was 18.9 ± 2.8 mm before treatment and 18.6 ± 3.4 mm after treatment. The mean proptosis value was not significantly decreased after treatment (P = 0.30).
Conclusions: The volume of orbital fatty tissue seemed to be unchanged after methylprednisolone pulse therapy while that of total extraocular muscles was decreased. The proptosis value seemed to be unchanged after treatment.
Keywords: Magnetic resonance imaging; Methylprednisolone pulse therapy; Proptosis; Thyroid-associated ophthalmopathy; Volume.