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IOID Differential Diagnosis Multispatial, infiltrative mass + bony involvement = primary tumor, metastasis, lymphoma, atypical meningioma, sarcoid, or GWP. IOID is a diagnosis of exclusion! Biopsy: Lymphocytic infiltrate with dense fibrotic tissue. Findings resolved at 2 year follow-up (After steroid tx) Imaging Features of IOID & GWP (CT or MRI) Both: Poorly marginated, enhancing mass IOID Classified into 6 types based on location: Anterior, Myositic, Diffuse, Apical, Perineuritic, Lacrimal Tolosa Hunt = cavernous sinus involvement GWP Polypoid sinonasal mucosal disease, +/- septal and nonseptal osseous destruction, periantral infiltrating disease *CT: Demineralization along perforating arteries (vasculitis) *MR: +/- Meningeal thickening, enhancement Idiopathic Orbital Inflammatory Disease (Pseudotumor) (IOID), Atypical fibrotic subtype. Axial (A, B) and coronal (C) CT in a 67 y.o. F with vision loss demonstrates a soft tissue mass causing widening of the superior orbital fissure (SOF) (red arrows). Axial T1 (D) and T2 (E) MRI images reveals that the hypointense lesion (yellow arrows) also compress the optic nerve along the inferior aspect of the orbital apex. It extends through the SOF to involve the right cavernous sinus (white arrows) and sella turcica (blue arrow). Avid homogeneous enhancement is present on T1 + C (F). Heterogeneous bone marrow is seen in the clivus and sphenoid bone (G, H). Coronal (H) and axial (I) T1+C delineate abnormally enhancing soft tissue in the right sella, cavernous sinus, and trigeminal cistern with extension along V3 through the foramen ovale (orange arrow) into the masticator space. Orbital Lymphoma A diffuse, infiltrative T1 (A) and T2 (C) hypointense, enhancing (B) mass is present within the right pre and postseptal orbital soft tissues on axial MRI in this 36 y.o. man with 1 week history of acute on chronic painless right eye swelling. Both intra and extraconal involvement extends to involve the orbital apex (red arrows) and results in proptosis. Diffusion restriction (red circles) (D) indicates a highly cellular process. Asymmetric fullness on the axial T1 +C image (B) reveals right cavernous sinus involvement (white arrow). Despite the significant extent of disease, no globe deformity is identified. Coronal (F) and axial (G) T1+C images demonstrate thickening and enhancement of the bilateral V2 (yellow arrows) and vidian (orange arrows) nerves, as well as the bilateral pterygopalatine fossae (blue arrows) and retromaxillary fat (G). Differential Diagnosis Based on imaging alone, it may be impossible to distinguish lymphoma from IOID, Graves orbitopathy, primary orbital tumors, or even cellulitis. A. The osseous orbit is composed of seven articulating bones, including the maxillary (M), lacrimal (L), ethmoid (E), lesser and greater wings of the sphenoid (LWS, GWS), frontal (F), zygomatic (Z), and palatine (*). B. The optic canal (blue) is housed in the LWS, and contains the optic nerve and ophthalmic artery. The superior fissure (SOF) (red) lies between the GWS and LWS. C. The SOF contents are divided into intraconal and extraconal components by the annulus of Zinn (blue), a tight fibrous ring from which the four rectus muscles arise (in red). The intraconal, medial SOF contains CN VI, the superior and inferior divisions of CN III, and the nasociliary nerve (branch of V1). The extraconal, lateral portion contains the superior ophthalmic vein (SOV), CN IV, and two additional branches of V1: the frontal and lacrimal nerves. The SOF provides communication between the orbit and middle cranial fossa via the cavernous sinus. (SR = Superior Rectus, LR = Lateral Rectus, IR= Inferior Rectus, MR= Medial Rectus). D, E. The posterior part of the inferior orbital fissure (IOF) (dark blue) lies in the infralateral aspect of the orbital apex, through which the maxillary nerve (V2) enters the orbit, having traversed the pterygopalatine fossa from the foramen rotundum (light blue). Additional structures crossing the IOF include the infraorbital branch of the maxillary artery, the inferior ophthalmic vein, and autonomic branches of the pterygopalatine fossa. All connections represent possible routes of spread for tumor and infection. Differential Diagnosis In the acute setting, findings may mimic thyroid orbitopathy, idiopathic orbital inflammatory disease, or even infection with SOV thrombosis. Cavernous- Carotid Fistula Axial T2 (A) and T1+C (B) show findings of congestive orbitopathy of the left eye in this patient with new HA, blurred vision, and left eye pain. Proptosis of the left globe, intra-conal fat stranding with enhancement, and EOM enlargement (red arrows) crowd the orbital apex. Coronal T1 +C images (C, D) reveal compromise of the optic nerve in the orbital apex (blue arrow) due to enlarge-ment of the EOMs and the SOV (C). Outward bulging of the cavernous sinus (CS) (yellow arrow) (D) and adjacent flow voids suggest a dural fistula. 3D TOF MRA (E) and lateral view ECA angiogram (F) reveal a left dural CCF. There is supply of the CCF by accessory middle meningeal artery branches. Note the early filling of the left CS (orange arrow) with anterior drainage via a dilated left SOV (green arrows) into the facial vein. Invasive Fungal Sinusitis 56 y.o. female on chronic immuno- suppression with 2 months of HA and progressive decline in left visual acuity. Axial fat-sat T1 +C (A, C, E) and 3D FIESTA (B, D) images reveal fullness in the left orbital apex (white arrow) with edema and enlargement of the optic nerve resulting in trapping of CSF within the optic sheath (B). There is evidence of perineuritis (blue arrows) along the optic nerve sheath (A). Orbital myositis causes left EOM enlargement (C). A surgically proven rim enhancing abscess (yellow arrows) is seen inferior to the optic nerve in the orbital apex. Note the presence of restricted diffusion (F) and lack of central enhancement in the abscess. Inflammation of foramen rotundum (red arrow), the cavernous sinus (orange arrow), and the trigeminal cistern within in Meckel’s cave (green arrows) are seen on coronal T1+C MRI (G). The left orbital inflammation is noted to be adjacent to rather minimal left ethmoid and sphenoid fungal sinusitis. Orbital Cellulitis 20 year old male presents with recent mononucleosis, sinus pain, periorbital soft tissue swelling, and two days of right eye pain (A-F). Axial and coronal enhanced CT scans reveal preseptal soft tissue cellulitis, right proptosis, and subtle postseptal cellulitis. Acute ethmoid sinusitis is seen bilaterally on the bone windows. A subperiosteal abscess (red arrow) is present along the right orbital roof. Inflammatory changes involve the superior rectus and superior oblique muscles as well as the lacrimal gland. The abscess is noted to extend into the orbital apex (yellow arrow). Intracranial extension is suspected on the CT scans due to the presence of small focal gas (blue arrows) collections and adjacent fluid within the subdural/epidural space. (G-H) Axial and coronal contrast enhanced MRI of the orbits and brain confirm a subperiosteal abscess along the orbital roof (green arrow) with associated intracranial extension of disease. There are bifrontal subdural empyema (orange arrows) as well as diffuse leptomeningeal and pachymeningeal thickening and enhancement (white arrows). F. Big Trouble in a Little Space: Orbital Apex Pathology Sara R. Nace, M.D., Tabassum A. Kennedy, M.D., Lindell R. Gentry, M.D. University of Wisconsin-Madison Department of Radiology VASCULAR DISEASE A. C. B. D. F. E. G. H. I. A. C. B. D. E. F. Imaging Features of Infection Edema/ Cellulitis * CT: Fat reticulation, enhancement of phlegmon, +/- muscle enlargement, bony erosion Intraorbital phlegmon * MRI: Isointense T1, bright T2 collection with rim enhancement and restricted diffusion Subperiosteal Fluid/ Abscess Acute Invasive Fungal Sinusitis * CT: Dense sinus secretions, foci of Ca++ and gas, +/- bony destruction * MRI: Variable T1 signal due to edema/fungus. Can mimic normal sinuses (low T1 & T2) Anatomical Routes of Spread THE PERIORBITA * Is the fibrous layer of periosteum which lines the entire orbit. Anteriorly it also contributes to the orbital septum. The septum helps to prevent the spread of preseptal infections into the postseptal spaces. * At the optic canal & superior / inferior orbital fissures, the periorbita fuses with the dura, providing a continuous fibrous connection between the potential subperiosteal and epidural spaces. This continuity accounts for extradural and subdural empyema, meningitis and parenchymal abscess. VENOUS STRUCTURES * The superior ophthalmic vein (SOV) drains via the lateral aspect of the superior orbital fissure into the cavernous sinus. This vein provides a route for spread of infection from the face and orbit posteriorly into the cavernous sinus. Differential Diagnosis Early: Imaging may appear similar to IOID (pseudotumor), GWP (Wegener’s), sarcoidosis, lymphoproliferative d/o, rhinosinusitis. Clinical symptoms, demographics will drive suspicion for infection. A. B. C. D. E. A. B. C. D. E. G. H. F. A. D. F. B. C. E. G. B. 5 Subtypes of Fungal Sinusitis Invasive Non-Invasive 1. Acute invasive 4. Non-Invasive 2. Chronic Invasive 5. Fungal mycetoma 3. Chronic granulomatous invasive Invasive fungal sinusitis is defined by the presence of fungal hyphae within the submucosa, bone or vessels of the paranasal sinuses. Acute Invasive Fungal Sinusitis Most lethal form of fungal sinusitis, 50-80% mortality Rapidly progressing infection seen in 2 distinct populations - Immunocompromised (severe neutropenia) ** 80% Aspergillus species - Poorly controlled diabetes (diabetic ketoacidosis) ** 80% Zygomycetes species (Rhizopus, Mucor, Rhizomucor) Granulomatosis with Polyangiitis (GWP) (Wegener’s Granulomatosis) Multisystem disease with triad Necrotizing granulomas in the upper and lower respiratory tract Necrotizing vasculitis of the lungs Glomerulonephritis Often fatal if untreated Ocular involvement in 18-50% of cases, spread from paranasal sinuses Symptoms include pain, vision loss and ophthalmoplegia Treatment- steroid and chemotherapy Dx: biopsy an high titer serum C-ANCA Idiopathic Orbital Inflammatory Disease (IOID) “Orbital Pseudotumor” Benign inflammatory process of unknown etiology composed of lymphocytic infiltrates May involve any part of the orbit Symptoms: acute onset orbital pain, proptosis, diplopia, restricted mobility and decreased visual acuity, 25% bilateral Dramatic response to steroids; however, 25% of cases recur INFECTION Postseptal Cellulitis Typically results from extension of sinus infection Complications - Superior opthalmic vein thrombosis - Cavernous sinus thrombosis - Loss of vision - Meningitis/intracranial extension Treatment: IV antibiotics; surgical drainage may be necessary Preseptal vs Postseptal Cellulitis Preseptal Limited to the soft tissues anterior to the orbital septum Contiguous spread of an infection of the face, teeth or ocular adnexa Treatment: oral antibiotic therapy University of Wisconsin-Madison Email: [email protected] www.radiology.wisc.edu REFERENCES 1. Aribandi M, McCoy VA, Bazan C 3rd. Imaging features of invasive and noninvasive fungal sinusitis: a review. RadioGraphics 2007; 27(5):1283–1296. 2. Aviv RI, Miszkiel K. Orbital imaging: Part 2. Intraorbital pathology. Clinical Radiology (2005) 60, 288–307 3. Capps EF, Kinsella JJ, Gupta M, et al. Emergency imaging assessment of acute, nontraumatic conditions of the head and neck. RadioGraphics. 2011; 31(1):316. 4. Jain R, Sawhney S, Koul RL, Chand P. Tolosa-Hunt syndrome: MRI appearances. Journal of Medical Imaging and Radiation Oncology (2008) 52, 447–451 5. Lakshamana DN, Newman B, Spottswood SS, et. al. Inflammatory Pseudotumor. RadioGraphics 2003; 23:719–729 6. Rene C. Update on orbital anatomy. Eye (2006) 20, 1119–1129 7. Smoker WRK, Gentry LR, Yee NK, et. al. Vascular lesions of the orbit: More than meets the eye. RadioGraphics 2008; 28:185–204 8. Som PM, Curtin HD, eds. Head and neck imaging. St. Louis, Mo.: Mosby Elsevier, 2011:674-724, 869-871 9. Vohra ST, Escott EJ, Stevens D, Branstetter BF. Categorization and characterization of lesions of the orbital apex. Neuroradiology (2011) 53:89–107 10. Waitzman AA, Birt BD. Fungal sinusitis. J Otolaryngol 1994; 23(4):244–249 Complete radiologic evaluation of orbital apex pathology requires an understanding of the complex anatomy of this region, broad categories of pathology which can manifest, and potential routes of disease spread that can lead to life- threatening complications. DISCUSSION The normal orbit arguably contains some of the most complex anatomy of the human body. The bony orbit is essentially a pyramid with four walls: a roof, lateral wall, floor, and medial wall. The apex of the orbital pyramid is situated at the posteromedial aspect and contains a high concentration of important neurovascular structures, which accounts for an orbital apex syndrome in the setting of pathology. The syndrome is manifested as multiple cranial nerve palsies, specifically of cranial nerves III, IV, and VI, along with sensory loss in the V1 distribution, accompanied by loss of vision and a relative afferent pupil defect. Findings can result from a wide variety of pathology, even in the absence of significant inflammatory signs or mass effect. Pathologies manifesting in this area includes infectious, inflammatory, neoplastic, and vascular etiologies. Orbital infections account for approximately 60% of primary orbital disease processes, and include orbital cellulitis, orbital abscess, and acute invasive fungal sinusitis. Inflammatory processes such as idiopathic orbital inflammatory disease (aka: pseudotumor), granulomatosis with polyangiitis (aka: Wegener’s), thyroid orbitopathy (Graves), and sarcoidosis can also affect the apex. Neoplasms such as lymphoma and leukemia can also be present in this region, as can optic nerve sheath tumors, sphenoid wing meningioma and metastatic disease. Lastly, vascular processes such as cavernous-carotid fistula and arteriovenous malformations can result in orbital apex involvement. The orbital apex provides the route of communication between the intracranial cavity and the orbit via the superior orbital fissure and the optic canal. These conduits may transmit tumor, infection, or inflammation between the two compartments. Given the potential for significant resultant morbidity and mortality, imaging is crucial to provide accurate, timely differential considerations, and to detect potential associated complications. CT examinations are rapid, cost effective, and provide superior bone detail in this region, while MRI lends high contrast resolution and the ability to characterize specific tissue without ionizing radiation. INTRODUCTION The unique, complex anatomy of the orbital apex results in a high concentration of important neurovascular structures in a small, confined space. As a result, cranial nerve palsies, vision loss, and a relative afferent pupil defect can result from a wide range of infectious, inflammatory, neoplastic, and vascular processes. The orbital apex is an important route of communication between the intracranial cavity and the orbit. Infectious and neoplastic diseases frequently spread along the complex pathways at the orbital apex. Familiarity with disease-related CT and MRI imaging findings is crucial to facilitate accurate, timely diagnoses, and to avoid disease morbidity as well as potential life-threatening complications. EDUCATIONAL OBJECTIVE Exhibit the anatomy of the orbital apex, and illustrate key CT and MRI imaging findings of some common pathologic processes manifesting in this region. SUMMARY Granulomatosis with Polyangiitis Axial multisequence MR imaging in a 57 y.o. F with nasal deformity and infraorbital nerve numbness demonstrates an infiltrative low T1 (A) and intermediate PD (B) signal intensity lesion in the right orbital apex (red arrows) that is avidly enhancing on T1+C (C). Abnormal enhancing soft tissue fills the bilateral pterygopalatine fossa and retro-maxillary fat (white arrows) (D). Extensive bilateral pachymeningeal enhancement is evident (blue arrows) on axial T1+C (E). Coronal T1+C reveals extensive enhancement involving the orbital apex, SOF and optic canal, bilaterally (orange arrows). Also involved are the maxillary and vidian nerves (F, G). Axial (H) and coronal (I) CT images 3.5 years prior to MRI exam show bilateral soft tissue masses in the pterygopalatine fossa as well as left cribriform plate erosion. I. H. A. B. C. D. E. F. D. I. G. A. B. C. F. E. H. GWP Differential Diagnosis Chronic rhinosinusitis, invasive fungal sinusitis, sarcoidosis, nasal cocaine necrosis, lymphoma INFLAMMATORY / GRANULOMATOUS DISEASE G. ORBIT ANATOMY NEOPLASM
