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Tomoaki Higashiyama, Yasuhiro Nishida, Yusuke Ichiyama, Sanae Muraki, Masahito Ohji; Signal intensity measurement of magnetic resonance imaging for extraocular muscles inflammation in thyroid-associated ophthalmopathy before and after methylprednisolone pulse therapy. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5900.
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© ARVO (1962-2015); The Authors (2016-present)
To quantitatively evaluate the extraocular muscles inflammation in thyroid-associated ophthalmopathy (TAO) before and after methylprednisolone pulse therapy, measuring signal intensity of magnetic resonance imaging (MRI).
The signal intensities of extraocular muscles were measured in 28 eyes of 14 patients with TAO before and after methylprednisolone pulse therapy and 19 eyes of 19 controls, using MRI at 3.0 Tesla with the STIR (short TI inversion recovery) technique. The MRIs of 2.5mm coronal slices were used for measuring the superior rectus (SR), inferior rectus (IR), lateral rectus (LR), medial rectus (MR) and superior oblique (SO) muscles. Signal intensity ratio of muscle to white matter was calculated to standardize signal intensity.
The mean signal intensity ratio of extraocular muscles in controls was 1.08±0.26 in SR, 1.32±0.29 in IR, 1.34±0.19 in LR, 1.47±0.25 in MR and 1.28±0.22 in SO. It was 2.20±0.62, 2.49±0.58, 2.05±0.49, 2.32±0.49 and 1.87±0.37 respectively in patients with TAO before treatment. Mean signal intensity ratio before treatment in the patients was significantly higher in all muscles compared with that in controls (P<0.001). The mean signal intensity ratio of extraocular muscles after the treatment in patients with TAO was 1.81±0.66, 1.87±0.60, 1.74±0.44, 1.95±0.49 and 1.59±0.36, respectively. Mean signal intensity ratio after the treatment was significantly decreased in all muscles compared with that before the treatment (P<0.001).
The measurements of signal intensity of MRI with the STIR technique could be used as a quantitative index for the inflammation in extraocular muscles in patients with TAO.
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