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To the Editor.
—It has come to our attention that unnecessary mistakes are being made in the evaluation of patients with unilateral exophthalmos using the EMI head scanner (developed by EMI Laboratories, Ltd, Middlesex, England). These scanners, for the most part newly installed, are usually overseen by a neuroradiologist or neurologist who may have little experience with the wide range of pathologic processes that occur within the orbit.Specifically, the swollen extraocular muscles associated with Graves disease or orbital myositis present an appearance that has been confused with an orbital tumor when viewed in tomographic section.There are several features that serve to distinguish the appearance of the swollen muscle from an orbit tumor. The swollen inferior or superior rectus muscle is seen in the orbit apex. The edge of the image formed by the obliquely sectioned muscle has a feathered or "paintbrush" appearance. This is caused by the
Trokel SL, Hilal SK. Computerized Axial Tomography in Patients With Exophthalmos. Arch Ophthalmol. 1976;94(5):867-868. doi:10.1001/archopht.1976.03910030435018