Orbital Pathology, EJR 2004

European Journal of Radiology 49 (2004) 105–142

Orbital pathology

W. Müller-Forella,∗, S. Pitzb

a Institute of Neuroradiology, Medical School University of Mainz, Langenbeckstrasse 1, D-55101 Mainz, Germanyb Department of Ophthalmology, Medical School University of Mainz, Langenbeckstrasse 1, D-55101 Mainz, Germany

Received 7 October 2003; received in revised form 8 October 2003; accepted 10 October 2003

Abstract

This overview of orbital pathology deals with different kinds of tumors, inflammatory, vascular, and traumatic diseases, which may involvethe orbit. Depending on the respective orbital compartment of the globe, the intrakonal, extrakonal and optic nerve the most important andmost frequent lesions are presented with their specific clinical symptoms. Their specific presentation on CT- and MR-imaging is discussed indetail, including the most important differential diagnosis.© 2003 Elsevier Ireland Ltd. All rights reserved.

Keywords: Idiopathic orbital inflammation; Retinoblastoma; Rhabdomyosarcoma; Metastasis; CT; MRI

1. Orbital pathology

Although more than 100 different clinical pathologiesmay affect the orbit[1] only some require diagnostic imag-ing. The knowledge of clinical signs and symptoms playsa crucial role in determining the appropriate investigation.The age of the patient may lead to the diagnosis, as inchildren the most frequent orbital diseases constitute ininflammatory processes, trauma or malignant tumors (e.g.rhabdomyosarcoma or neuroblastoma), while in the groupof elderly patients neoplasms represent the main patholo-gies. As already mentioned in the anatomical section, theconsideration of the four compartments of the orbit (theglobe, the intrakonal and the extrakonal space and the opticnerve itself with its menigeal layers) may help in differentialdiagnosis of the different diseases. In this short overview wewill present the most frequent inflammatory and tumorousdiseases and some characteristic traumatic lesions of eachof these compartments.

2. Globe

The majority of the diseases of the globe are assessed byophthalmologic methods and do not need imaging, but in

∗ Tel.: +49-6131-17-7139; fax:+49-6131-17-6643.E-mail address: [email protected]

(W. Müller-Forell).

case of leucocoria or cataract MR-imaging (MRI) may berequired. Its high resolution is able to visualize not only thepathology itself but accompanying retinal detachment and/oreffusion.

2.1. Inflammatory disorders

Although rare, the posterior scleritis represents the localform of the idiopathic orbital inflammation, predominantlyaffecting females[2]. Clinical presentation is characterizedby a slowly progressing, painful proptosis accompaniedby decreased vision, due to thickening of the sclera andchoroidal folds. Histologically the inflammation presentsdiffuse or localized, necrotic or granulomatous, and scleralsequesters are found with leakage of proteinaceous edemafluid into the interstice of the uvea and Tenon’s capsule[3,2].

CT- and MR-imaging of scleritis is characterized by dif-fuse scleral thickening of different extent and infiltration ofthe adjacent tissue with contrast enhancement, depending onthe extent of the inflammatory process (Fig. 1a–c). Nodularscleritis does not show contrast enhancement[2,4], an im-portant criterion in differential diagnosis to uveal melanoma.

2.2. Tumors

The neoplastic diseases of the globe may arise fromdifferent layers, the most significant diagnosis are theretinoblastoma in childhood and the uveal melanoma in theadult patients.

0720-048X/$ – see front matter © 2003 Elsevier Ireland Ltd. All rights reserved.doi:10.1016/j.ejrad.2003.10.011

106 W. Müller-Forell, S. Pitz / European Journal of Radiology 49 (2004) 105–142

Fig. 1. MR of a 48-year-old man with right hemicrania, orbital pain and edema of the right eyelid. Diagnosis: posterior scleritis of the right eye. (a)Axial T2w view demonstrating the retrobulbar inflammation (plus edema) of the right side. (b) Corresponding T1w native view with isointense signalof the retrobulbar infiltration. (c) Corresponding T1w contrast-enhanced (fat suppressed: FS) view with bright signal enhancement (white arrow).

W. Müller-Forell, S. Pitz / European Journal of Radiology 49 (2004) 105–142 107

Fig. 2. A 2-year-old boy with leukokoria of the left eye. Diagnosis:retinoblastoma. (a) The axial CT demonstrates not only spots of calcifica-tion but slight hyperdensity of the left vitreous body. (b) Correspondingproton density (PDw) MR, where the tumor itself (white star) looks isoin-tense, while bilateral retinal detachment show bright signal (white arrows).(c) Corresponding T1w contrast-enhanced (FS) view. Note the intensiveenhancement of the tumor, but intermediate signal of the subretinal fluid.

Fig. 3. A 2-year-old boy presenting with leukokoria and complete reti-nal detachment of the left eye. Diagnosis: Coat’s disease. (a) Axial CTwith only slight hyperdensity of the entire left globe, which also demon-strates a diminution, compared to the right. (b) Corresponding IR view,where the characteristic V-shaped, bilateral retinal detachment is seen.The hyperintensity represent some hemorrhage, the arrow indicates theremaining vitreous body. (c) The corresponding T1w contrast-enhanced(FS) image demonstrates only slight enhancement of the detached retina,and lack of enhancement of the remaining vitreous body behind the lens(white arrow) (with permission of Müller-Forell[15]).


2.2.1. RetinoblastomaRetinoblastoma, a highly malignant tumor arising from

neuroectodermal cells of the retina, represents the most com-mon intraocular tumor in childhood, striking more than 90%children younger than 5 years of age, at an equal sex contri-bution[5,6]. There are non-heritable and inherited forms, thelatter are autosomal dominant. A chromosome 13q14 bandmutation is seen in all patients with bilateral occurrence andin 15% with unilateral disease[7–9].

Leukokoria is the most common clinical sign, found in60% of the patients, followed by strabismus, and (rather rare)pain caused by secondary glaucoma[5]. Imaging should beused in the diagnosis of retinoblastoma, although ophthal-moscopy may confirm tumors as small as 0.002 mm. Espe-cially MR is able to define tumor extension in all aspectsof the globe, an eventually extraocular extension, intracra-nial metastasis, and/or a second tumor. Bilateral retinoblas-

Fig. 4. MR of a 74-year-old man with progressive visual deficit of the left eye. Diagnosis: Choroidal melanoma. (a) Axial T2w view with hypointensetumor of the medial circumference of the left globe. Note bilateral retinal detachment (white arrows). (b) Corresponding T1w native view where thetumor demonstrates a hyperintense signal. (c) Corresponding T1w contrast-enhanced view with bright signal of the enhancing tumor.

toma with or without pinealoma (trilateral retinoblastoma)are found in about 25–35% of the cases[10].

Consequently MRI is the method of choice as it has notonly the diagnostic potential concerning small intraocularlesions (especially when surface coils are used), but the abil-ity of three dimensional examination, combined with thehigh resolution of potential intracranial pathology, especiallyafter injection of paramagnetic gadolinium[11–13], leav-ing CT-examination with its demonstration of calcification(Fig. 2a) only for cases of differential diagnostic problems.MR is able to define the different growth patterns of endo-phytic, exophytic of diffuse retinoblastoma[14,12]. On T1wand proton density images retinoblastoma appears slightlyhyperintense compared to normal vitreous, the latter en-abling a better visualisation of accompanying retinal detach-ment, while on T2w images the tumor is seen as an areaof low signal intensity. After injection of contrast medium


retinoblastoma exhibit a moderate to marked enhancement,especially on fat-suppressed sequences (Fig. 2a–c) [6,13].

The most important differential diagnosis of retinoblas-toma are lesions also presenting with leucocoria like per-sistent hyperplastic primary vitreous (PHPV), and Coat’sdisease (Fig. 3) [15] while endophthalmitis, retinal detach-ment, toxocaria and choroidal hemangioma are rather rare[12,16,17].

2.2.2. Malignant uveal melanomaThe incidence of malignant uveal melanoma, the most

common primary intraocular tumor in adults, increaseswith age and ranges from 5.2 to 7.5 cases per million peryear at a mean age of 53 years[6,18]. Usually diagnosis ofuveal melanoma is made by ophthalmoscopy, fluorescein

Fig. 5. MR of a 60-year-old female with visual deficit of the right eye. Diagnosis: choroidal melanoma with initial destruction of Bruch’s membrane.(a) Axial T2w view of the inferior orbit, where the tumor of the right globe demonstrates a hypointense signal. (b) Corresponding T1w native view.(c) Corresponding T1w contrast-enhanced (FS) view of the inferior globe, where the melanoma demonstrates a characteristic bright enhancement. (d)Coronal T1w contrast-enhanced (FS) view, where a slight irregularity of the inferior circumference (white arrow) indicates the extraocular growthof thetumor (confirmed by histology).

angiography and ultrasound, but imaging is required incase of opaque lens or extensive subretinal effusion[2,6].Uveal melanoma may arise from benign choroidal nevi,not demanding imaging, but regular ophthalmoscopic con-trol. The most common starting-point is the choroid (85%)(Fig. 4), while the ciliary body (9%), and the iris (6%) arerather rare locations (6). Uveal melanoma present with dif-ferent growth patterns: the most common is circumscribednodular, a diffuse growth is seen rather rare. In case ofa mushroom-like appearance the tumor progression intothe orbit is caused by the rupture of Bruch’s membrane[6,19], a finding to direct one’s attention especially in earlystages (Fig. 5), as the therapy is different from that of ex-clusively intraocular melanoma. As in retinoblastoma, MRis the imaging of choice, although the elevated, primarily


hyperdense, sharply circumscribed enhancing tumors areseen on CT. Melanin produces stable free radicals, whichcause a paramagnetic proton relaxation enhancement, thatshortens both T1- and T2-relaxation times, and resulting ina moderately high signal in T1w and PDw images, whilesignal reduction is seen on T2w images (Figs. 4 and 5) [20].The well defined tumor present in up to 95% hyperintense(with respect to the vitreous) in T1w, and hypointense inT2w images, and demonstrate a bright signal enhancementafter gadolinium injection, especially in fat-suppressed im-ages, which enables the detection of small tumors as well asan additional differentiation to retinal detachment (Fig. 4)[3,12,19,21].

Differential diagnosis should include choroidal heman-gioma, choroidal nevi, choroidal detachment, neurofibroma,

Fig. 6. A 19-year-old male car accident victim (no seat belts worn at the time of the accident!). At the follow-up (6 months after the accident), the patientpresented with suspicion of endophtahlmitis. Diagnosis: right globe rupture with vitreous body hemorrhage, multiple orbital wall fractures, developingposttraumatic phthisis. (a) Axial CT, showing multiple fractures of all orbital walls, with penetrating fragment into the globe, vitreous hemorrhage, andpost-bulbar hematoma (black arrow). (b) Corresponding T1w native view 6 months later with shrunken right bulb in the inferior orbit, and dislocationofthe medial external muscle and fat into the fractured ethmoidal sinus. (c) Corresponding contrast enhanced (FS) view with enhancement of the fibrousscar tissue as intense as the enhancement of the external muscles (with permission of Müller-Forell[15]).

disciform degeneration of the macula, and metastasis[2].

2.2.3. Different retinal and choroidal lesionsChoroidal hemangioma is a congenital vascular hamar-

toma seen in middle-aged to elderly patients with neu-rocutaneous syndromes, which may present solitary ordiffuse [2,22]. On CT/MR they present as lenticular, hy-perdense/hyperintense (in both T1- and T2w-images) wellcircumscribed structure in the juxtapapillary or macu-lar region with a marked/intense contrast enhancement[2,6,15]. It should not be mistaken with the capillary he-mangioma in Hippel-Lindau syndrome, where imaging isindicated in order to confirm/rule out cerebellar or spinalcord hemangioma, as diagnosis ofretinal hemangioma is


Fig. 7. Axial CT of a 78-year-old woman, who fell in the course of a basal ganglia infarction. Diagnosis: acute vitreous hemorrhage. Note the hyperdensityof the left vitreous body compared to the right, combined with a slight swelling of the left eyelid.

based on its typical ophthalmoscopic appearance[23,24].The rather rarechoroidal osteoma is typically seen inyoung females before completion of the third decade oflife. This benign ossifying tumor contains marrow, mastcells, loose fibrovascular elements, and mesenchymalcells. On imaging it presents as a sharply demarcated,lentiform calcification on CT, on MR with a high signalon non-enhanced T1w and low signal on T2w images, anda marked signal enhancement after gadolinium injection,simulating both retinoblastoma and choroidal melanoma[2,6,15,25].

2.3. Traumatic lesions

Although the globe, its neurovascular structures and mus-cles are protected by the bony orbit and the shock-absorbingfat the ocular bulb as the most anterior structure of the visualsystem is extremely vulnerable. In case of impaired ophthal-moscopy (e.g. extreme swelling of the eyelid) CT can visu-alize rapidly and accurately the full extent of the injury. Onthe other hand, after a trauma, the external integrity of theglobe and orbit should never lead to the assumption of intactretroglobal structures, since innocuous orbital trauma mayproduce devastating functional deficits. Injury of the globemay occur as a component of major facial trauma (Fig. 6) oras an isolated event (Fig. 7). Orbital injuries may be causedby blunt and penetrating trauma[26,27]. While the formeris due to an impact with low-velocity forces, the latter is aresult of impact at proportionally high energy with penetrat-ing of the object (Fig. 8).

In case of orbital trauma, CT is the method of choice,as, beside the readily availability it enables both accuratevisibility of bony and soft-tissue lesions and exact localiza-tion of (mostly ferromagnetic) foreign bodies without riskof dislocation. The scope of ocular injuries includes a great

variety of lesions, ranging from rupture of the globe to dis-location of the lens, from vitreous (Fig. 7), subretinal, retro-hyaloid hematoma to retroocular hemorrhages. In the sequelof severe ocular trauma, phthisis bulbi refers to a scarred,shrunken globe, possibly associated with dystrophic calcifi-cation, as a type of developmental microphthalmia (Fig. 6)[4].

3. Konal/intrakonal area

3.1. Inflammatory lesions

With more than 60% inflammation is the far most commondisease of the orbit, the majority of which are related tothyroid orbitopathy[1].

3.1.1. Idiopathic orbital inflammationSince the commentary of ROOTMAN[28] the term

orbital pseudotumor, routinely used for a diversity of dis-orders, which represent the most frequent pathologic pro-cess of the orbit, should be discontinued. As this termhas contributed to diagnostic confusion both clinically andpathologically, it should be replaced by a more specificdefinition regarding the underlying pathophysiological andclinical patterns. Idiopathic orbital inflammation is one ofthe four major intraconal disorders, the other include infil-trative, mass effect and vascular disorders. They all presentwith different but specific clinical symptoms, requiring theindividual diagnosis in an individual case, following con-sideration of specific finding on imaging, the age of thepatient, systemic evaluation and the result of biopsy[28].Though, systemic steroid therapy may be regarded as apragmatic therapeutic strategy in the majority of inflamma-tory cases, but histological confirmation of the underlying


Fig. 8. CT of a 35-year-old male with foreign body accident 3 days before, presenting awake but with hemiparesis of the left side. Diagnosis: perforationof the right globe by a nail, with intracranial penetration and basal ganglia hemorrhage. (a) Axial midorbital view, showing the shrunken right globe,and some air bubbles in the right orbit. (b) Axial view of the brain at the level of the basal ganglia, where the hemorrhage of the lateral basal ganglia isseen, in combination with some small air inclusions. The metallic artifacts are caused by the nail in the occipital lobe. (c) Lateral scout, demonstratingthe intracranial position of the nail.

pathologic process should be mandatory, since some tu-mors, especially lymphomas are characterized by similarpresentation and therapeutic answer[29]. Histological cel-lular components of idiopathic orbital inflammation presentextremely variable, consisting of mature lymphocytes, lym-phoid follicles, plasma cells, neutrophil and eosinophilgranulocytes, histocytes and macrophages[29–31]. Bi-

lateral involvement is considered to be a manifestationof chronic progressive immune-mediated generalized fi-brosis, observed in cases with additional retroperitonealfibrosis (M. Ormond) or in Erdheim-Chester disease[32–34].

A classification into non-specific infections and infes-tations, and specific non-infectious inflammation[1] is


Fig. 9. Axial CT of a 14-year-old girl with painful, progressive exophthalmos of the right eye. Diagnosis: diffuse idiopathic orbital inflammation. There isa diffuse scleral thickening of the entire circumference, distinct, hazy hyperdensity of the retrobulbar fat, diffuse swelling of the external rectus muscles,including the tendinous insertion.

helpful on pathological purposes, but in clinical practice amorphologic classification of idiopathic orbital inflamma-tion according to a (1) diffuse and (2) local form seems tobe useful[4,6,35]. In diffuse idiopathic orbital inflamma-tion every orbital structure may be involved (Fig. 9), whilein the localized form only one of the different parts of theorbit is affected (Fig. 10).

CT- and MR-imaging characteristics are unspecific, in-cluding contrast enhancement, due to high vascularity ofthe inflammatory process, infiltration of the fat, proptosis,and an isolated or general, uni- or bilateral extraocularmuscle enlargement[3]. Differential diagnosis to true or-bital tumors may be difficult, but clinical characteristicswith painful acute to subacute, mostly unilateral propto-sis may help, especially in the acute form. If only onemuscle is affected, diagnosis of myositis, the local presen-tation of an idiopathic orbital inflammation is most likely(Fig. 10). Beside the mainly single muscle involvement,another characteristic sign, helping in differential diagnosisof myositis versus Graves’ disease, is the involvement ofthe tendon into the inflammatory process, demonstrating onimaging as additional (or only) swelling and enlargement(Fig. 11).

3.1.2. Graves’ disease (syn. thyroid orbitopathy,M. Basedow)

Dysthyroid endocrine orbitopathy is the most frequentcause of uni- or bilateral proptosis in adults, mainly associ-ated with the autoimmune hyperthyroidism (synonym: M.Basedow or Graves’ disease)[36–38]. As in the retroorbital

tissue, especially in extraocular muscles, TSH-receptorsand thyrotropin receptor antibodies (TRAb) are found,these compartments seem to be the main target of thisinflammatory process[39]. Lymphocyte inflammation, mu-copolysaccharid and plasma cell infiltration lead to tissueedema of all orbital structures, demonstrating not onlyenlargement of extraocular muscles, but corresponding in-crease of retrobulbar fat volume[40], while in more chronicstages, collagen deposition in the effected muscles resultin fibrosis, and may be associated with fat deposition[41].Apart from the classical clinical and ophthalmologicalsymptoms, and endocrinological findings, where elevatedthyroid hormone levels were found even in clinical absenceof hypderthyroidism[39] imaging is indicated for primarydiagnosis as well as for control examination in the courseof the disease. Spindle shaped spreading of typically morethan one of the extraocular muscles (>4 mm) without in-volvement of the corresponding tendon (Fig. 12a–c) [42],and the preferential affection of the inferior and medialrectus muscles, followed by the superior and lateral ex-traocular muscles, and the compression of the optic nervein the orbital apex (“crowded orbital apex syndrome”[43])are the most important morphological diagnostic criteria ofendocrine orbitopathy. Although the morphological accu-racy of CT is similar to MR, the latter is the most effectivetool not only in establishing the initial diagnosis but alsoin the course of endocrine orbitopathy. MR enables thecalculation of T2-relaxation time (Fig. 12h) [44,45], thusallowing the differentiation between an acute and chronic,fibrosing form, which is of greatest interest with regard to


Fig. 10. MR of a 20-year-old female presenting with acute, painful proptosis of the left eye. Diagnosis: myositis of the left lateral rectus muscle. (a)Axial T1w midorbital view, where a swelling of the entire lateral rectus muscle is seen. (b) Corresponding T2w view with bright signal enhancementof the affected muscle. (c) The coronal T2 view shows an additional involvement of the superior rectus muscle and levator palpebrae complex (note thebright signal enhancement of both maxillary sinus mucosa as a sign of acute sinusitis).

the decision whether the patient may or may not benefitfrom immunosuppressive and/or radiation therapy[46,47].Surgical decompression with removal of different orbitalwalls is indicated in case of optic neuropathy and providesspace for the enlarged muscles as well (Fig. 12f and g) [48].

Differential diagnosis of Graves’ orbitopathy includeslymphoma, metastasis, diffuse or focal idiopathic orbitalinflammation with mass effect, and vascular diseases likecarotid-sinus cavernosus-fistula (CCF)[49]. As alreadymentioned, the most important differential diagnosis ismyositis, especially in rare cases of unilateral involvementof thyroid orbitopathy.

3.2. Solid tumors

Peripheral nerve tumors account for about 4% of allorbital tumors with a preference to (plexiform) neurofi-

bromas and schwannomas as the orbit is host of a greatnumber of nerves including the motor branches of the cra-nial nerves III, IV and VI, and the sensorial branches ofcranial nerve V, as well as sympathetic and parasympa-thetic nerves[50]. On imaging schwannomas demonstratea well-defined intra- or extrakonal ovoid mass with vary-ing degree of contrast enhancement[51], while (plexiform)neurofibroma present with an irregular, often infiltratingmass with marked enhancement, due to the high vascularcomponent[52].

3.2.1. LymphomaOrbital lymphoma accounts for up to 55% of all ma-

lignant orbital tumors[53], including a heterogeneousgroup of neoplasms of the lymphoproliterative systemwith distinct entities defined by clinical, histological, im-munological, molecular, and genetic characteristics[54].


Fig. 11. MR of a 53-year-old female, suffering from painful double vision of the right eye. Diagnosis: myositis of the right superior oblique muscle.(a) Coronal PDw view with hyperintensity of the tendon of the right superior oblique muscle (black arrow), adjacent to the trochlea. (b) CorrespondingT1w view, demonstrating the slight swelling of the right tendon (black arrow), compared to the left. (c) Axial T1w, confirming the thickening of theaffected tendon (black arrow).

They include benign, atypical and malignant lesions,and most of those involving the orbit are B-cell lym-phoma, although orbital lymphoma primarily belong tolow-grade non-Hodgkin-lymphoma (NHL) or extranodalmucosa-associated lymphoid tissue (MALT lymphoma)[55]. The patients, mainly older than 50 years, present withpainless, mostly unilateral proptosis and with or withoutmotility disturbances or decrease of visual acuity, but dis-placement of the globe. The methods for the assessment oforbital lymphoma include ultrasound, CT and MR. As anyorbital compartment may be involved (with predilection forthe lacrimal gland), there is a wide spectrum of imagingfindings from well defined, round or lobulated, but not en-capsulated mass to less defined infiltrative process (Fig. 13)[55].

3.3. Vascular lesions

Vascular lesions are an important and substantial compo-nent of orbital anomalies, but their classification, whetherthey are vascular tumors or vascular malformation is dis-cussed controversially[56,57].

3.3.1. HemangiomaHemangiomas are the most frequent vascular tumors of

the orbit.Capillary hemangioma, which consist of plump,rapidly dividing endothelial cells with lumina of varyingsize, pericytes and multi-laminated basement membranes,are seen in young children[56]. Present at birth they showa tendency of spontaneous involution, sometimes with com-plete disappearance within the first 5 years of life[58].


In case of extended orbital involvement there is a highrisk of visual acuity deficits as well as distortion of theorbital contents, eventually demanding more aggressivetherapy [57], as surgery, laser treatment and/or adminis-tration of intralesional steroid or interferon therapy. Onimaging they present as lobulated, irregularly marginatedparenchymal mass, demonstrating a bright contrast en-hancement (Fig. 14), especially on fat suppressed T1w MRimages.

Cavernous hemangiomas of the adult, predominantly aris-ing in the intrakonal space, consist of enlarged, ectatic (cav-ernous) venous spaces, surrounded by a capsule of fibroustissue[59]. The leading clinical symptoms are slowly pro-

Fig. 12. A 61-year-old female presenting with bilateral axial proptosis and chemosis. Diagnosis: Graves’ disease. (a) Axial CT of the midorbital region,demonstrating the bilateral extraorbital location of both globes, and the lacrimal glands. Note the spindle-shaped enlargement of the medial and lateralexternal rectus muscles, but slim tendons. (b) Corresponding PDw view with moderate signal enhancement of the medial rectus muscles, correspondingto intramuscular edema. (c) Corresponding T1w view. (d) Coronal CT, where the involvement of all external muscles is apparent, including the superioroblique muscle. (e) Corresponding T1w MR. (f) Axial CT after surgical decompression. Note the increased size of the muscles, invaginating the entireformer ethmoidal sinus. (g) Corresponding coronal view. (h) T2-time calculation in coronal view with bright signal of the external rectus muscles,indicating a recurrent inflammation with edema (corresponding to the clinical presentation).

gressing, painless, axial exophthalmos, occasionally withmild visual deficits, due to optic nerve compression or exten-sion by stretching; choroidal folds or papilledema are foundin some 25% of patients. Imaging characteristics consist ofa well outlined, round or oval, mainly intrakonal mass, thatusually (but not always) spares the orbital apex (Fig. 15).Calcification, due to phlebolits are well detected by CT, onMR cavernoma present iso- to hypointense on T1w imageswith a generally extensive, but delayed contrast enhance-ment, while on T2w series the lesions exhibit a hyperintensehomogeneous at times irregular signal. The main differentialdiagnosis is an orbital varix, which may also demonstrate awell-delineated mass, but may present with an intermittent


Fig. 12. (Continued ).

proptosis on Valsalva maneuver. Hemangiopericytoma, fi-brous histiocytoma and neurinoma should also be consid-ered[60].

3.3.2. Orbital venous anomalyThe nomenclature of “orbital varix” is discussed con-

troversially, since it is thought to be the same underlyingabnormality as the venous lymphatic malformation, propos-ing the term orbital venous anomaly[61]. As orbital veinsdo not have valves, these abnormally dilated veins enlargeduring systemic pressure changes, as coughing, forced ex-piration, or bending forward, resulting in variable proptosis,the main clinical symptom. On imaging, orbital venousmalformation present as intrakonal, well-defined, triangu-lar configured mass, tapering toward the apex, with highlyintensive, homogeneous contrast enhancement (Fig. 16)[57].

3.3.3. Venous lymphatic malformationOccurring in the head and neck, predominantly in chil-

dren and young adults, the venous lymphatic malformation(until recently called lymphangioma) is considered to bea vascular anomaly of unknown origin[57]. It containsabortive vessels, which spread among normal structuresand present as an unencapsulated, primarily thin-walledmass with numerous cystic spaces of different size. Itshows a tendency to spontaneous hemorrhages, resultingin a sudden onset of proptosis combined with perior-bital swelling and reduced eye motility, at times leadingto optic nerve compression[62], thus indicating promptimaging as clinical symptoms may be similar to rhab-domyosarcoma. On imaging they present as an infiltrative,multilobulated mass with poor encapsulation, found aswell intra- as extraconal, harbouring sometimes calcifica-tion, seen on CT. Due to slowly growth, an asymmetric


Fig. 13. CT of an 82-year-old woman with slowly progressing painless,unilateral, extra-axial proptosis of the left eye. Diagnosis: lymphoma: (a)axial and (b) coronal view with a clearly defined retro-and supra-bulbarmass, presenting slight enhancement. No separation of the external mus-cles is seen, but adaptation to the contour of the globe; the latter findingexcludes the presence of hemangioma as a specific diagnostic criterion(with permission of Müller-Forell[15]).

enlargement of the effected orbit may be seen (Fig. 17).The most important differential diagnostic criterion, de-marcating it from cavernous hemangioma and/or idiopathicorbital inflammation is the lack of contrast enhancement[63].

3.4. Miscellaneous

Thrombosis of orbital veins is characterized by an in-travasal mass in the dilated (mostly) superior ophthalmic

Fig. 14. CT old, a 3-month-old boy with progressive exophthalmos devel-oping in the second and third month of life, accentuated when screaming.Diagnosis: juvenile capillary hemangioma. (a) Axial contrast-enhancedview, where a homogeneous irregular mass is seen in the retrobulbarcompartment of right orbit, involving the external muscles, but sparingthe apex region. (b) The coronal view delineates the mainly inferior andmedial location.

vein. Depending on the imaging technique used, on CT, aprimarily hyperdense, dilated vessel is seen without any con-trast enhancement, while on MR, the appearance depends onthe age of the thrombosis and the paramagnetic propertiesof haemoglobin[6].

Carotid-cavernous fistula (CCF) represents an arteriove-nous shunt of the internal carotid artery in its cavernoussegment to the superior ophthalmic vein (respectively arteri-alized). The resulting venous congestion of the orbit causeshypervolemia, clinically manifesting as pulsatile exophthal-mos, combined with dilated episcleral vessels, chemosisof different extent, secondary glaucoma, eventually pa-pilledema, ocular pain, and ophthalmoplegia[64], whichmay lead to vision loss as a result of increased intraorbital


Fig. 15. MR of a 53-year-old man with slowly progressing proptosis of the right eye, and a retrobulbar mass seen on ultrasound. Diagnosis: cavernoma.(a) Axial T2w midorbital view, demonstrating a hyperintense, solid, well defined mass in the right lateral intrakonal compartment. (b) Corresponding T1wnative view, where a slight impression of the globe is seen, responsible for the development of choroidal folds. (c) Corresponding T1w contrast-enhancedview, where the impression of the posterior circumference of the globe is apparent (white arrow). (d) Midsagittal image of the right orbit, presenting theintraconal location, inferior to the optic nerve.

pressure. The etiology may be traumatic or spontaneous, thelatter occurring primarily in diabetic older women. Patho-physiological classification of CCF into high-flow (type A)and low-flow (type B) fistula (Fig. 18) is crucial in determin-ing the definite therapy[65]. Color-coded ultrasound candefinitely demonstrate reversal blood flow. The mentionedclinical symptoms with (mostly) unilateral proptosis, com-bined with imaging features of enlarged external musclesand widening of the superior ophthalmic vein is indicativefor CCF. Although on both, CT- and MR-angiography a di-agnosis can be done, digital subtraction angiography (DSA)remains the examination of choice, especially since in

type-A-fistula an interventional therapy can be performed.Differential diagnosis of a dilated superior ophthalmic veinshould include cerebral arteriovenous malformation (AVM)with atypical venous drainage[66].

4. Extrakonal area


4.1.1. Orbital infectionsOrbital infections, relatively common in children as

a complication of paranasal sinusitis, are classified as


Fig. 16. T1w contrast-enhanced (FS) MR of a 42-year-old man with recurrent exophthalmos. Diagnosis: orbital venous anomaly. A sharply defined,hyperintense lobulated mass is seen medial and lateral to the optic nerve, with some extension into the orbital apex (black arrow).

Fig. 17. CT of a 2-year-old boy, who suffered from an acute hemorrhagic exophthalmos of the right eye, suspicious for rhabdomyosarcoma. Diagnosis:venous lymphatic malformation. (a) Axial view of the midorbital region. A multilobulated mass is seen mainly in the medial superior orbit, with inferiordislocation of the globe and some calcification (not shown). Note the enlargement of the right orbit, compared to the left, due to long lasting intraorbitalmass. (b) Corresponding contrast-enhanced view, where the choroid, basilar and carotid artery, and the cavernous sinus are seen hyperdense, but notthemass itself.


Fig. 18. A 84-year-old diabetic woman presented with progressive exophthalmos and vision loss of the right eye. Diagnosis: low-flow carotis-sinuscavernosus fistula (CCF). (a) Axial T1w contrast-enhanced (FS) midorbital view, where the protrusion of the right globe is apparent, as well as thethickening of the external muscles, and additional retinal detachment (white arrow), all due to venous congestion. (b) Axial T1w native view of the upperorbit, demonstrating the massive enlargement of the right superior ophthalmic vein (black arrow) compared to the left (white arrow). (c) Coronal PDwview with high signal intensity of the dilated right superior ophthalmic vein (black arrow). (d) Lateral view of the right internal carotid artery (ICA)(arterial phase) with digital subtraction angiography (DSA), with filling of the inferior part of the cavernous sinus (black arrow). (e) Corresponding earlyvenous phase with the dilated superior ophthalmic vein, normally not seen.


Fig. 19. Axial contrast-enhanced CT of a 2.5-year-old boy with febrile state and reddish swollen left eye and face. Diagnosis: preseptal cellulitis.Thesoft tissue inflammation respects the orbital septum (small white arrow).

Fig. 20. Contrast-enhanced CT of a 4-year-old girl, suffering from chronic nasal sinusitis, acute presenting with febrile state and suspicion of infectedmucocele. Diagnosis: subperiostal abscess of the left orbit. (a) Axial midorbital view, demonstrating the necrotic abscess between the lamina papyraceaand the dislocated, swollen periorbita. Note the normal hypodensity of extraconal fat (white arrow) and the infection of the ispilateral ethmoid sinus. (b)The coronal view shows the infection of the entire ipsilateral sinuses, but no muco- or pyocele.


Fig. 21. Contrast-enhanced CT of a 7-year-old boy with chronic sinusitis, actual presenting with progressive loss of consciousness and a febrile state.Diagnosis: subperiostal orbital and epidural intracranial abscess as orbital complication of nasal sinusitis. (a) Coronal view of the orbit, showingthe irregular enhancing intraorbital extraconal soft tissue mass, and abscess of the left frontal sinus. (b) Axial view of the brain demonstrating anextraparenchymal fluid with enhancing capsule (dura), with typical biconvex configuration of epidural mass. Some intracranial air confirms the connectionwith the extracranial space.

bacterial preseptal cellulitis, subperiostal abscess, orbitalabscess, and cavernous sinus thrombosis[67]. Preseptalcellulitis, a bacterial infection of the skin and subcutaneoustissue, clinically presents as an erythema with severe pain,lid edema, chemosis, and pseudo-proptosis (Fig. 19). Theorbital septum as a reflection of the periorbita provides an

effective barrier against intraorbital infection, as does theperiorbita at the lamina papyracea[67]. In an advancedstage postseptal soft tissue infiltration along the orbital wall,and replacement of the fat and subperiostal space may leadto orbital phlegmone. Subperiostal abscess is mainly due tothe spread of infection through the congenital dehiscences


Fig. 22. A 25-year-old man presenting with unspecified pressure of the left orbit persisting for several months and a recent onset of double vision.Diagnosis: mucocele of the left ethmoid sinus. MR. (a) Axial PDw view with a hyperintense, well delineated, cystic structure of the left middle ethmoidregion. (b) Corresponding T1w contrast-enhanced image, demonstrating pressure exerted on the periorbita and an attenuated, impressed, and dislocatedmedial rectus muscle. Note the hyperintense line of the wall of the mucocele in combination with the periorbita (small black arrow). (c) Coronal T1wview with intraorbital expansion and flattening of the medial rectus muscle (black arrows), and dislocation of the superior oblique muscle (white arrow).CT: (d) corresponding coronal CT (bone window) with characteristic biconvex configuration of the ethmoid cell and thinned bony cortex (white arrows)((b) and (d) with permission of Müller-Forell[15]).

and foramina of the thin orbital bones (Fig. 20) [67]. Oncontrast-enhanced CT, a sharply defined, extrakonal, spaceoccupying mass with marginal ring-enhancement is seen.On MR, the subperiostal abscess is characterized by anintermediate signal on T1-weighted and proton densityimages, with marked rim enhancement on the correspond-ing contrast enhanced views. Intracranial extension maylead to severe complications as, e.g., epidural or subduralabscess (Fig. 21), purulent meningitis, or cavernous sinusthrombosis.

4.1.2. Muco-/pyoceleMucoceles are inflammatory lesions of the nasal sinuses,

most commonly resulting from inflammatory obstruction of

the ostium of an affected sinus (primary mucocele), or as aresult of posttraumatic, postoperative or neoplastic obstruc-tion (secondary mucocele). They act as space occupying le-sions, containing a mucous sac lined by mucous membrane.In case of superinfection the mucous retention is referredto as pyocele, presenting with a marginal contrast enhance-ment [4]. The characteristic presentation of a mucocele onimaging is the crescent-shaped, sharp and thinned remod-eling of the bony wall of the affected sinus, combined withthe mass effect to the extrakonal space (Fig. 22). The ap-pearance of mucocele on MR may present in different ways,depending on the extent of hydration of the sinus secretion.A high signal of the sinus on T2w images (correspondinglow signal on T1w) may be due to high free water content.


Fig. 23. MR of a 14-year-old boy with initial complaint of double vision, followed by painless protrusion of the left eye after 1 week. Diagnosis:rhabdomyosarcoma. (a) Axial PDw image of the inferior orbit, showing slight hyperintensity of the tumor lateral to the left inferior rectus muscle. (b)Coronal T1w native view with only slight hypointensity of the tumor, compared to the inferior rectus muscle (black arrow).

Fig. 24. CT of a 60-year-old man with extra-axial proptosis of the right eye. Diagnosis: hemangiopericytoma. Spherical tumor of the right extraconalspace, dislocating, but not infiltrating the medial rectus muscle up to the optic nerve. Medially extension into the ethmoid sinus with bony destruction.


Fig. 25. A 65-year-old woman, presenting with slight proptosis of the right eye, diffuse pressure in the orbital region, and difficulty in nasal breathingfor a period of several months. Diagnosis: esthesioneuroblastoma. (a) Axial contrast-enhanced CT, showing a large tumor occupying predominantlythe right ethmoid and sphenoid sinus, and crossing the midline. Although the medial orbital wall is destroyed (black star), and intraorbital extraconaltumor expansion with medial dislocation of the normal sized medial rectus muscle is visualized, the presence of a small fat border (white arrow)indicates sparing of the periorbita. (b) Corresponding T1w native MR demonstrating the thin periorbita (small white arrow) and the extraconal fat(white arrow). Note the expansion to the bony optic canal. (c) Coronal contrast-enhanced CT, where the intracranial expansion is apparent, becauseof destruction of the frontal skull base. (d) T1w contrast-enhanced (FS) view demonstrating the entire cranio-caudal extension of the tumor not onlywith solid tumor part, reaching the endocranium, but inferior necrotic area in the nasal cavity. Note the hypointensity of the right maxillary sinus,simulating air in the sinus, but compared with the corresponding CT it contains inspisated mucous retention ((b) with permission of Müller-Forell[15]).

With increasing dehydration a high signal is seen on bothT1w and T2w images, while in case of inspisated secretionthe signal may decrease in both weightings, simulating nor-mal air content (Fig. 25). In order to avoid false negativefindings, CT should be performed in clinically suspectedmucocele[4].

4.2. Tumors

The extrakonal space is the first orbital compartment thatprimary (e.g. osteoma, hemangiopericytoma) or secondary

(nasal/paranasal) orbital tumors invade on their way todeeper orbital or even intracranial structures.

4.2.1. RhabdomyosarcomaRhabdomyosarcoma (RMS) is the most common, highly

malignant, soft-tissue tumor in childhood with up to4–8% of all children less than 15 years of age, and aslight predilection for boys (5:3)[68,22]. Arising fromprimitive mesenchymal cells, four different subgroups ofrhabdomyosarcoma can be divided histopathologically:(a) the embryonal rms, mainly arising in childhood, and


Fig. 26. A 78-year-old man presenting with epistaxis and numbness of the left check. Diagnosis: carcinoma of the left maxillary sinus. (a) Axial nativeCT showing soft tissue in the inferior left orbit with poor distinction from the lateral rectus muscle. (b) Corresponding T2w MR, where necrotic tumorparts present with high signal. (c) Coronal T2w view. Although destruction of the orbital floor (including infraorbital canal (V2), responsible for thenumbness of the left cheek) is apparent, the inferior rectus muscle (black arrow) is only dislocated but not infiltrated. Note the big maxillary cyst oftheright side. (d) Corresponding T1w native view identifying additional pronounced destruction of the maxillary sinus floor (white arrow) ((a), (c) and(d),with permission of Müller-Forell[15]).

representing the most malignant variant, (b) the pleomor-phic rms, the tumor type of the adult, (c) the alveolar typeof young adults, and (d) the botryoide rhabdomyosarcoma[69]. The characteristic clinical presentation is an extremelyrapidly progressing exophthalmos in an otherwise healthychild, with dislocation of the eye, disturbance of motility,sometimes combined with unilateral ptosis and/or subcu-taneous hematoma. On imaging the usually well-definedtumor is isodense/isointense to the orbital external muscleson CT/T1w images, demonstrating a marked enhance-ment, due to its high vascularisation, more prominent onfat-suppressed MR (Fig. 23) [6,35]. Rapid histopatholog-ical confirmation is mandatory, as modern chemotherapywas demonstrated to lead to successful remission and a

survival rate of 93%[70]. Differential diagnosis shouldinclude venous lymphatic malformation, lymphoma, andintraorbital neuroblastoma as well as idiopathic orbitalinflammation.

4.2.2. Various tumors (hemangiopericytoma, olfactoryneuroblastoma, sinunasal malignancies, Langerhans-cellhistiocytosis)

Hemangiopericytoma, consisting of numerous sinu-soidal vascular spaces, lined by endothelial cells, andsurrounded by proliferating pericytes are very rare anduncommon orbital tumors[57], which recommend com-plete surgical excision, because of frequent recurrence[71]. Imaging demonstrates a circumscribed, generally


Fig. 27. CT of a 74-year-old man with known lung-carcinoma presented with progressing exophthalmos of the right side. Diagnosis: metastasis of lungcarcinoma. (a) Axial, contrast enhanced midorbital view, demonstrating the medial protrusion of the right globe due to a soft tissue mass in the lateralextra- and intraconal compartment with poor distinction of the lateral rectus muscle and/or lacrimal gland. The enhancing mass extends into the ispilateraltemporal fossa. (b) The coronal view shows the inferior dislocation of the right globe, the tumor invades the endocranium with destruction of the orbitalroof including the frontal bone. (c) The coronal view in bone window of the posterior orbital region exhibits the extended tumor infiltration of thezygomatic, sphenoid, and fronto-temporal bone.

encapsulated markedly enhancing mass, in case of infiltra-tion of adjacent tissue, bone erosion is best seen on CT(Fig. 24).

Olfactory neuroblastoma (syn. esthesioneuroblastoma)represent an uncommon malignant ectodermal tumor orig-inating from bipolar olfactory receptor cells high in themucosa of the nasal cavity, affecting both sexes with anapproximately equal frequency at any age[72]. After longstanding symptoms of nasal obstruction and anosmia, re-current epistaxis leads to imaging, where the involvementof the orbit, and sometimes the endocranium represents analready advanced stage (Fig. 25).

The orbit may be involved secondarily by any sinus lesionthat is inflammatory or neoplastic. Especiallycarcinoma, the

most common sinunasal neoplasms may not only infiltratethe orbit, but extend to the endocranium (Fig. 26). Metastasisinvolvement of the orbit is known to be the first manifestationof an occult primary malignancy, accounting for 1.5–8%of all orbital tumors[1], with preference of breast, lung(Fig. 27), and prostate carcinoma.

Langerhans-cell histiocytosis (LCH) is a disease of un-known origin with variable clinical manifestation, rang-ing from non-progressive solitary eosinophilic granulomato progressive and aggressive multisystemic involvement[73]. Solitary or monostotic eosinophilic granuloma is themost common presentation of LCH in children. Typicallyaffecting the skull vault and presenting as well defined cir-cumscribed mass, the lesion presents isodense/isointense to


Fig. 28. MR of a 6-year-old boy who presented with slight proptosis and a rapidly growing mass of the left temporal region. Diagnosis: Langerhans-cellhistiocytosis (LCH). (a) Axial T2w image with a hypo- to isointense mass in the temporal fossa and adjacent bone. (b) Corresponding T1w native view,where the infiltration of the cortex of the sphenoid and temporal bone and intracranial, but extracerebral extension of the lesion is apparent (black arrow).Note the normal size of the left lateral rectus muscle. (c) Corresponding contrast-enhanced view with marked enhancement of the tumor. Note that partsof the periorbita (black arrow) are respected. (d) Coronal T1w native view, demonstrating the infiltration of the temporal muscle (white star), explainingthe suspected first diagnosis of a rhabdomyosarcoma.

cortical gray matter on CT/T1w MR, with a marked con-trast enhancement, while on T2w images it appears with ahypointense signal (Fig. 28) [22].

4.3. Lacrimal gland

Lacrimal gland lesions mainly present as unspecific en-largement of the gland, and can be divided into epithelial andnon-epithelial lesions, the former including largely neoplas-tic disorders, while the latter consist of mostly congenital,inflammatory, but also neoplastic disorders.

4.3.1. Congenital lesionsThe lacrimal gland represents the only “organ” of the

extrakonal compartment, giving rise to different pathologic

processes, and demanding imaging only in some case oftumors, rarely in case of inflammatory diseases. The mostcommon congenital lesion is the dermoid cyst, arising fromepithelial remnants of embryonal epithelial tissue, charac-terized by a slowly, painless growth. Containing fat, skinappendices (hair) or sebaceus gland[74], they present onimaging as well-circumscribed, round to ovoid encapsu-lated mass in the upper lateral orbit (Fig. 29). On CT thefatty components result in hypodensity, calcification may beseen. Sometimes a shallow impression of the bone, adjacentto the frontozygomatic suture, is apparent, where in some(rare) cases a small portion may extent into the temporalfossa, causing a so-called dumbbell-shaped orbital dermoid.On MR, the significant content of fat results in a hyper-intense signal both on T1w and T2w images, and distinct


Fig. 29. CT of a 32-year-old woman with slight painless protrusion of the right eye. Diagnosis: dermoid of the right lacrimal gland. Slight enlargementof the right lacrimal gland, compared to the left side, with hypodense (fat) area (white arrow) in the anterior part.

Fig. 30. A 86-year-old woman with a long history of extra-axial proptosis of the left eye. Diagnosis: pleomorphic adenoma of the left lacrimal gland. (a)Axial contrast-enhanced CT with a predominantly solid, partly calcified encapsulated tumor of the left upper extraconal space, with significant depressionand flattening of the anterior dislocated globe. (b) Corresponding T1w contrast-enhanced view with more distinct differentiation of the capsule andthecystic tumor parts (with permission of Müller-Forell[15]).


Fig. 31. MR of a 35-year-old woman, who presented with painful protrusion of the right eye. Diagnosis: adenoidcystic carcinoma. (a) Axial T2w imageof the upper orbit, demonstrating a hyperintense signal of the slightly enlarged right lacrimal gland with moderate impression of the upper globe. (b)Corresponding T1w native view, where an initial destruction of the fronto-zygomatic suture is seen (white arrow). (c) The coronal T1w, contrast-enhanced(FS) view demonstrates the marked contrast enhancement of the affected gland, compared to the left side. Note the impression of the globe (white arrow).

signal enhancement on diffusion weighted imaging (DWI)[75].

4.3.2. TumorsThe most common benign tumor of the lacrimal gland,

producing an inferior and medially dislocation of the globeis thepleomorphic adenoma, affecting mainly middle-agedto old patients. This benign mixed, slowly growing tu-mor, originates mainly from the inner lobe of the lacrimalgland. Imaging features represent the histological con-ditions, as the tumor presents as a well circumscribed,encapsulated mass with heterogeneous densities/signals,due to myxoid, chondroid, or mucinous areas[76](Fig. 30).

The adenoidcystic carcinoma as the most malignant tu-mor of the lacrimal gland, account for 29% of all epithelial

lacrimal gland tumors[77], affecting patients of any agewith a peak in the fourth decade and patients of either sex.They present with a hard mass in the upper lid, often as-sociated with persistent pain, due to infiltrative perineuralgrowth, even in small tumors[1]. On CT or MR, a lesscircumscribed, nodular mass in the lacrimal fossa withadditional bone erosion suggests adenoidcystic carcinoma(Fig. 31).

The lacrimal gland is the at most touched intraorbitalstructure affected by the wide spectrum of lymphomatouslesions that range from reactive lymphoid hyperplasia,low-grade mucosa associated lymphoid tissue (MALT)lymphoma, to malignant lymphoma of various types, in-cluding the malignant NHL[78]. Mainly older patientspresent with a painless, slowly growing mass in the up-per lid, leading to an inferior displacement of the globe.


Fig. 32. CT of a 86-year-old woman with chronic blepharo-conjunctivitis of the left eye, known NHL for the past 9 years, actually presenting withprogressing exophthalmos of the left eye. Diagnosis: non-Hodgkin-lymphoma (NHL). (a) Axial native midorbital view with diffuse involvement of theextraconal space, but no distinction of the lateral rectus muscle. (b) Axial contrast-enhanced view of the upper orbit, showing the involvement of theentire upper orbit, laterally and medially to the compressed superior rectus muscle, which presents slightly hypodense.

In some cases combined with conjunctival redness and/orvisual impairment[76], a palpable smooth mass is seen in50% of the patients, appearing as a pink, “salmon-colored”lesion. Lymphoma present on imaging as an infiltrative, ho-mogeneous mass of the lacrimal gland (Fig. 32), mouldingadjacent structures without causing indentation. On MR,they show a moderate to marked hypointensity on T2w im-ages, while on T1w views hyperintense signal compared toextraocular muscles is demonstrated with a marked contrastenhancement, especially in fat-suppressed images[6,54].Infiltration of the adjacent bones and intracranial extensionis seen in malignant variants[6,76].

4.4. Traumatic lesions

Traumatic orbital lesions are manifold, reaching fromsmall fissures, presenting only with orbital emphysema, to

severe osseous destructions. Certain orbital fractures occurwith greater frequency: the most common are fracturesof the orbital floor and medial walls (lamina papyracea)(Fig. 33), while those of the orbital roof (about 5%)(Fig. 34), lateral wall (Fig. 35) or complex orbital rim frac-tures are rather rare[79]. As already mentioned biplanarhigh-resolution/multislice CT with secondary reconstruc-tions is the imaging modality of choice in orbital trauma,while MR is required in evaluating vessel injuries or in thedetection of non-metallic foreign bodies[79]. In blow-outfractures (isolated orbital wall fractures without involve-ment of the orbital rim) a sudden increase in intraorbitalpressure from a traumatic impact to the orbital soft tissueresult in expansion and outward displacement of the thinorbital floor and/or fragile lamina papyracea. Restricted eyemotility is due to incarceration of parts the fine networkof fibrous septa that functionally unites the periosteum


Fig. 33. CT of a 69-year-old man, who was involved in a free fight, presented with monocular hematoma and severe exophthalmos of the right eye.Diagnosis: orbital and subconjunctival emphysema, due to fracture of the lamina papyracea. (a) Axial view of the midorbital region demonstrates thesubconjunctival emphysema. (b) Axial view of the upper orbit, where the orbital structures are fading over by the extreme intraorbital emphysema. (c)The coronal view shows the site of the fracture of the lamina papyracea (white arrow), as source of the connection of the nasal/paranasal cavity with theorbit.

of the orbital floor, the inferior fibrofatty tissue, and thesheaths of the inferior and oblique rectus muscle (Fig. 36).The so-called “hanging drop” represents a small localhematoma or fibrofatty displacement at the fracture site(Fig. 36).

5. Optic nerve


The term optic neuritis includes a variety of idiopathic,infectious or demyelinating diseases, clinically presenting(among others) with an acute uni- or bilateral loss of cen-tral visual acuity, central scotoma, loss of colour vision,

and an afferent pupillary defect with or without associatedretroocular pain on eye movement and pathologic visualevoked potential (VEP)[80]. The most common underlyingpathologies are multiple sclerosis, with optic neuritis as thefirst symptom, and acute disseminating encephalomyelitis(ADEM). Infections, caused by various agents (e.g. cy-tomegalovirus, varicella zoster, mycosis or tuberculosis),and different autoimmune diseases (e.g. lupus erythemato-sus, autoimmune vasculitis) may also be responsible foroptic neuritis[81].

Again, the imaging method of choice in optic neuri-tis as an intrinsic lesion is MR, as it demonstrates onone side the localization of the affected area, with pref-erence to the intraorbital and intracanalicular portions ofthe optic nerve (Fig. 37), on the other hand, MR is able


Fig. 34. CT of a 22-year-old man with state after a free fight and thrust with a knife-injury. Diagnosis: traumatic frontal encephalocele. (a) Axial viewof the upper orbit, where a soft tissue mass is seen in the medial upper orbit, and defect (black arrow) with bony fragment of the medial orbitalroof. (b) Coronal view, where the drop-like mass of the encephalocele (white arrow) dislocates the medial rectus muscle. (c) Corresponding bonewindow, demonstrating the wide defect of the skull base. (d) Axial view of the basal brain, showing a small intraparenchymal hematoma in the frontallobe.

to define the underlying cerebral pathology. In additionto increased signal intensity of the affected area on T2w-and FLAIR-images, focal contrast enhancement is seenin the majority of patients after gadolinium not only inacute, but in even persistent neuritis, as an expression ofblood-optic-nerve-barrier (BOB) disruption[81].

5.2. Tumors

As the optic nerve is part of the central nervous system,two different types of optic nerve tumors should be differ-entiated, the intrinsic optic nerve glioma, and the extrinsicoptic nerve sheath meningeoma.


Fig. 35. CT of a 24-year-old man with state after a car accident. He presented with extreme swelling and hematoma of the right eyelid. Diagnosis:fracture of the lateral orbital wall. (a) Axial view of the midorbital region with severe swelling of the eyelid and subcutaneous area of the temporal fossa,but no sign of retrobulbar hematoma. (b) Axial view of the upper orbit, showing several bony fragments in the lateral extraconal space, and hematoma inthe anterior part. (c) The coronal view in bone window demonstrates the intraorbital dislocation of the zygomatic bone fragments in the upper extraconalspace.

5.2.1. Optic nerve gliomaHistopathologically proven as (juvenile) pilocytic astro-

cytoma, this benign, slow-growing tumor of low radiationsensibility, may affect the visual system at different loca-tions in different extension: on the optic disc, intraorbital,and intracranial, the latter with or without involvement ofthe chiasm. Optic nerve glioma account for 66% of allprimary optic nerve tumors, and 4% of all orbital lesions[82], the preferred affected group are children and youngadults, without any sex predilection[83]. The incidencein patients suffering from NF1 is rather high, as about50% of patients with NF1 harbor optic nerve glioma, abilateral disease considered to be pathognomonic[6]. Vi-sual dysfunction is found in about 47% of the patients

[84], but the incidence of symptomatic optic pathway tu-mors is less than 20%[22]. Although CT may defineasymmetric enlargement of the affected optic nerve, MRshould be the method of choice, as it is able to definethe lesion with superior contrast resolution and clear mor-phology. The question, whether the second optic nerve,and/or the chiasm and optic tract are involved additionallyis answered best by MR. On T2w images, the effectednerve demonstrates homogeneous high signal compared tothe contralateral unaffected nerve, due to the intraneuralgrowth pattern with expansion of fibrovascular trabeculaeby intra-axial astrocytic proliferation, combined with cys-tic degeneration (Fig. 38a). Another hyperintense portion,surrounding the isointense compressed nerve should not be


Fig. 36. CT of a 20 year-old man with double vision and acute proptosis of the right eye after kick-box training. Diagnosis: blow-out fracture of theorbital floor. (a) Axial view of the midorbital region, showing some small retrobulbar hematoma, without mass effect. (b) The coronal view demonstratesthe piercing of the inferior rectus muscle by a bony fragment (white arrow), lateral to a prolapsus of orbital fat into the maxillary sinus (so-called“hanging drop”). Note the hyperdensities of small intraconal hematoma, compared to the left side. (c) Corresponding bone window, where the additionalhematosinus (with fluid level) is apparent.

Fig. 37. MR of a 21-year-old male with recurrent visual deficit of both eyes. Diagnosis: left optic nerve neuritis of unknown origin. (a) Axial T1w nativeview. (b) Corresponding contrast-enhanced (FS) view with bright signal enhancement of the left pre-canalicular and canalicular optic nerve compartment(white arrow).


Fig. 38. MR of a 4-year-old girl with known NF1, presenting with progressive proptosis of the left eye. Diagnosis: optic nerve glioma. (a) Ax-ial T2w midorbital view with enlargement of the intraorbital compartment of the left optic nerve. The hyperintensity of the optic nerve sheathcomplex represents a combination of subarachnoid space and arachnoidal gliomatosis. (b) Corresponding T1w native view. (c) Corresponding T1wcontrast-enhanced (FS) image, demonstrating the tumor expansion into the subarachnoid space. Note the impression of the optic disc (white ar-row), visible expression of papilledema. (d) Coronal T1w native view with enlargement of the left optic nerve complex, compared to the rightside.

mixed up with a widened subarachnoid space, as it rep-resents the perineural arachnoidal gliomatosis suggestivefor patients with NF1[85] (Fig. 38a and c). T1w pre- andpostcontrast images, the latter with fats-suppression tech-nique (Fig. 38c), delineate best subtle blood-brain-barrier(BBB) disruption in the optic nerve itself and/or in thecourse of the visual pathway (chiasm, optic tract, and hy-pothalamus). Additional intrinsic cerebral lesions, seenin NF1-patients with optic nerve glioma are astrocytoma,with preference to the brainstem[86]. Differential diag-nosis of optic nerve glioma should include demyelinatingoptic neuritis, idiopathic inflammation of the optic nerve,optic nerve sheath meningeoma, sarcoidosis, and evenmetastasis.

5.2.2. Meningeoma of the optic nerve sheathUnspecific clinical symptoms of slowly progressing,

painless visual loss and unilateral proptosis or transientvisual obscuration in middle-aged adults (mean 40 years),with a female predominance, are seen in patients withoptic nerve sheath meningeoma. This primarily benign,slowly growing neoplasm arises from arachnoid cap cellswithin the optic nerve sheath complex, or from someintraorbital portion of sphenoid wing meningeoma[87](Fig. 39).

Optic nerve sheath meningeoma present in three differentpatterns[6]: (1) diffuse, with thickening of the optic nervesheath complex (Fig. 39), sometimes with tubular calcifica-tion of the nerve sheath (the so-called “tram-track-sign”),


Fig. 39. MR of a 81-year-old woman with headache since years, known visual loss of the right eye, but progressive visual deficit of the left eye. Diagnosis:optic nerve sheath and sphenoid wing meningeoma of the right side with compression of the chiasm. (a) Axial T1w native view of the midorbital regionwith delineation of an enlargement of the right optic nerve sheath complex. (b) Corresponding contrast-enhanced (FS) image, demonstrating not onlythesignal enhancement of the optic nerve sheath but an enlargement and enhancement of the ispilateral cavernous sinus too (white arrow). (c) Coronal T1wnative view of the midorbital region, showing the different diameter of both optic nerves. (d) Coronal T1w contrast-enhanced (FS) view of the region ofthe optic canal. Note the enhancement of the right optic nerve in the canal (long white arrow), compared to the left (short black arrow), and the duralenhancement of the sphenoid plane (black star). (e) Coronal T1w contrast-enhanced view at the level of the optic chiasm, demonstrating not only thecompressive dislocation of the chiasm to the left side (white arrow), but the tumor involvement of the right cavernous sinus and skull base.


Fig. 40. MR of a 73-year-old woman with progressive visual deficit of the right eye. Diagnosis: tubular optic nerve sheath meningeoma. (a) Axial T1wcontrast-enhanced (FS) view of the midorbital region, demonstrating the tubular growth of the meningeoma (so-called “tram-track-sign”) of the rightoptic nerve sheath. (b) Corresponding coronal view, where the compressed optic nerve is seen as a centrally located hypointense area (white arrow) (withpermission of Radiologen am Brand, Mainz).

Fig. 41. MR of a 55-year-old woman with slowly progressing axial proptosis of the right eye, examined for possible endocrine orbitopathy. Diagnosis:eccentric meningeoma of the optic nerve sheath. (a) Axial PDw midorbital view with a well-defined intraconal mass of isointense signal. (b) CorrespondingT1w native view, demonstrating a homogeneous, apparently encapsulated mass. (c) Corresponding contrast-enhanced (FS) view with homogeneous, butintermediate signal enhancement. (d) Coronal T1w contrast-enhanced image demonstrating the encapsulation of the nearly normal sized optic nerve (withpermission of Müller-Forell[15]).


best, but not exclusively seen on CT (Fig. 40), (2) fusiform,with circumscribed swelling of the sheath complex or (3) asan eccentric tumor (Fig. 41). The imaging method of choiceagain is MR, as it provides not only a high sensitivity andspecificity (despite its lower sensitivity for calcification) butany intracranial extension via the optic canal can be provedor ruled out, even in small and en-plaque growing tumormatrix. On T2w images, the tumor presents with iso- toslightly hyperintense signal, on T1w images it is isointensecompared to the external muscles. Due to high vascularityand the absence of a BBB, the demonstration of a homo-geneous, moderate to marked signal enhancement of the tu-mor, especially in fat-suppressed sequences is significant,clearly delineating the tumor from the compressed, isoin-tense optic nerve (Fig. 41d). The subtle analysis of imagingcriteria concerning the relation to adjacent/involved struc-tures may help in sometimes difficult differential diagnosisof cavernous hemangioma and eccentric optic nerve sheathmeningeoma.

5.3. Trauma

Single traumatic lesions of the optic nerve are rare, as intraumatic disorders of the face and orbit, the optic nerve isonly one of multiple structures involved.

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