Imaging Anatomy and Pathology of Extraocular Muscles in Adults Christian B. van der Pol, MD, Santanu Chakraborty, MD, Jennifer Gao, MD, Thanh Nguyen, MD, Carlos Torres, MD, Rafael Glikstein, MD  Canadian Association of Radiologists Journal  Volume 65, Issue 4, Pages 366-371 (November 2014) DOI: 10.1016/j.carj.2014.05.001 Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 1 (A) Coronal computed tomography (CT) image of the normal orbit anatomy. The circle marks the cone created by connecting the EOMs, which forms a border between the extraconal and intraconal spaces. (B) Sagittal CT image of the same patient. e = extraconal space; i = intraconal space o = optic nerve. Canadian Association of Radiologists Journal 2014 65, 366-371DOI: (10.1016/j.carj.2014.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 2 (A) A 46-year-old woman with Grave disease presented with bilateral proptosis. A coronal computed tomography (CT) image, reveals enlarged bilateral medial and superior recti, bilateral superior oblique muscles, and left inferior rectus. The lateral recti (especially the right [asterisk]), the inferior oblique muscles, and the right inferior rectus are spared. (B) A 54-year-old man who presented with proptosis from Graves ophthalmopathy. An axial CT image, revealing thickening of the right medial rectus (asterisk), with relative sparing of its tendinous attachments to the globe. The right globe is displaced medially with an abnormally oriented lens. The optic nerve also is displaced by mass effect. (C) The same patient in (B) after decompressive surgery. An axial CT image, showing bilateral lamina papyracea resection. The left medial rectus was noted to have markedly enlarged in the interval since the prior study. (D) Coronal T2-weighted magnetic resonance image (MRI) of an 81-year-old woman with a history of Graves ophthalmopathy and prior orbital decompression. All EOMs are enlarged and hyperintense, which suggests acute inflammation. (E) A coronal T2-weighted MRI of a 64-year-old woman with a history of Graves ophthalmopathy, demonstrating enlargement and increased signal of the right superior rectus, consistent with acute inflammation. Note the lateral and inferior recti are enlarged bilaterally but do not show increased inflammatory signal. Canadian Association of Radiologists Journal 2014 65, 366-371DOI: (10.1016/j.carj.2014.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 3 (A) An axial computed tomography (CT) image, revealing orbital myositis in a 62-year-old woman who presented with pain, swelling, diplopia, and decreased range of motion. The right lateral rectus is enlarged (arrow), and there is subtle stranding of the retrobulbar fat. (B) Coronal CT image of the same patient. Subtle stranding is demonstrated in the right retrobulbar fat (arrow); there were no fluid collections or sinusitis. Canadian Association of Radiologists Journal 2014 65, 366-371DOI: (10.1016/j.carj.2014.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 4 (A) Axial T2-weighted magnetic resonance image (MRI) of a 69-year-old woman with breast cancer, demonstrating an extraconal mass in the right orbit. (B) Axial T1-weighted MRI after contrast, revealing heterogenous enhancement. The lesion was found to be metastatic leiomyosarcoma. (C) An axial computed tomography (CT) of the head of a 65-year-old woman with breast cancer metastases in the right medial rectus (arrow). (D) Coronal T2-weighted MRI in a 50-year-old man with left eye proptosis, revealing an extraconal mass that involves the superior rectus and levator palpebrae superioris. He was diagnosed with large B-cell lymphoma. (E) Coronal T1-weighted MRI after contrast, demonstrating enhancement within the same mass. (F) Coronal CT image in an 86-year-old woman with new diplopia; focal thickening is demonstrated within the right lateral rectus; this was a relapse of large B-cell lymphoma; irregularity and apparent fat stranding around the left lateral rectus on the provided image was due to volume averaging from the globe. Canadian Association of Radiologists Journal 2014 65, 366-371DOI: (10.1016/j.carj.2014.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 5 (A) A 29-year-old man with a left orbital blowout fracture after a punch to the eye. An opacity that extends inferiorly from the orbit into the left maxillary sinus (white arrow) could be mistaken for a mucocele given the intact orbital rim (black arrow). However, the clinical history and maxillary sinus fluid level (arrowhead) suggest otherwise. (B) A coronal computed tomography (CT) image of the same patient; there is herniation of the retrobulbar fat and inferior rectus muscle. (C) A coronal CT image of a 59-year-old man with a right orbital blowout fracture after falling; entrapment of the inferior rectus was suspected. Note the traumatic hematoma within the right maxillary sinus. (D) A 34-year-old man who presented after a motor vehicle collision; a coronal CT image, revealing stranding in the extraconal and intraconal spaces around the left superior rectus muscle, with no associated fracture, which is suggestive of an ill-defined hematoma and/or contusion. (E) Sagittal CT image of the same patient in (D); pneumocephalus is present. Canadian Association of Radiologists Journal 2014 65, 366-371DOI: (10.1016/j.carj.2014.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 6 (A) A 17-year-old girl with a 2-day history of sinusitis, as suggested by opacified ethmoid air cells. She was found to have pre- and postseptal cellulitis, characterized by fat stranding around the left medial rectus on coronal computed tomography (CT); there also is subperiosteal thickening along the medial left orbital wall, with mass effect on the medial rectus. (B) An axial CT image, demonstrating fat stranding in the same region; the subperiosteal thickening extends the entire length of the orbit and contains a tiny locule of air, which is concerning for phlegmonous changes and early subperiosteal abscess formation. Canadian Association of Radiologists Journal 2014 65, 366-371DOI: (10.1016/j.carj.2014.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 7 (A) A 95-year-old woman with right eye proptosis, conjunctival injection, and decreased visual acuity; an axial computed tomography image, showing enlargement of the right extraocular muscle. (B) The superior ophthalmic vein is enlarged as well (arrow); note, there is senile calcification of the right anterior sclera. (C) A conventional angiogram was performed in the same patient, which revealed low-flow shunting between the right internal carotid artery and cavernous sinus (arrowhead); the right meningohypophyseal artery was communicating with the cavernous sinus, in keeping with an indirect carotid-cavernous fistula. Canadian Association of Radiologists Journal 2014 65, 366-371DOI: (10.1016/j.carj.2014.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions