International Journal of Current Medical And Applied Sciences, 2018, May,18(3),59-66. REVIEW ARTICLE Orbital Space Occupying Lesions in Adults with MRI Imaging Parate Ramesh1, Arti Anand1, Prajwalit Gour1, Tilottama Parate2 & Khobragade Nikita3 1Professor, 2Associate Professor, 3Junior Resident, Department of Radiology, Government medical college and Hospital, Nagpur [MS], India- 440009. --------------------------------------------------------------------------------------------------------------------------------------- Abstract: A wide variety of space occupying lesions are encountered in the orbit in adults. CT and MR imaging frequently help confirm the presence of a mass and define its extent. Characteristic imaging features may help distinguish among lesions that have overlapping clinical presentations. Common vascular lesions include: cavernous hemangioma. Benign tumors that are reviewed include: optic nerve sheath meningioma and nerve sheath tumours. Malignancies include: lymphoma, metastasis and lacrimal gland tumours. Inflammatory and infective conditions like pseudotumours, hydatid cyst, epidermoid cyst, fungal granuloma. Key imaging features that guide radiological diagnosis are discussed and illustrated. Keywords: Intraconal and extraconal tumors, Primary orbital tumor, T1-weighted and T2-weighted MR images. Introduction: A wide array of processes can produce space-occupy the classification of vascular malformations by the inglesions in and around the orbit. These include benign International Society for the Study of Vascular and malignant neoplasms, vascular lesions, Anomalies (ISSVA), cavernous hemangioma is a venous inflammatory disease, and infection, among othercauses. or low flow malformation. Orbital cavernous Imaging is used to localize a lesion and establish a hemangioma demonstrates a predilection to affect diagnosis or generate a differential diagnosisthat guides middle-aged women [2] (60%–70%), with a mean age of management, to follow a known lesion forprogression, 43 to 48 years and range of 18 to 72 years based on or some combination of these. several large series. Because they exhibit slow We review a few pathologies forming space occupying progressive enlargement, the most common presenting lesion in orbit of adults with MRI as the modality of sign and symptom is painless proptosis. On gross choice to confidently distinguish between similar examination, orbital cavernous hemangioma are benign appearing lesions and to arrive at a single most likely noninfiltrative masses that appear as dark ‘‘plum’’ or diagnosis. purplish-colored ovoid lesions within a well-defined Cavernous hemangioma: fibrous pseudocapsule consisting of trabeculations and Cavernous hemangioma has often been cited as the most septae. common primary orbital tumor in adult [1]. According to Address for correspondence: Dr. Khobragade Nikita Access this Article Online Post-Graduate Student, Department of Radiology, Website: Government Medical College, Nagpur [MS], India. www.ijcmaas.com Email: [email protected] How to cite this article: Parate Ramesh, Arti Anand, Prajwalit Gour, Tilottama Parate & Subject: Khobragade Nikita: Orbital Space Occupying Lesions in Adults with MRI Medical Sciences Imaging International Journal of current Medical and Applied sciences; Quick Response Code 2018, 18(3),59-66. IJCMAAS,E-ISSN:2321-9335,P-ISSN:2321-9327. Page | 59 Parate Ramesh, Arti Anand, Prajwalit Gour, Tilottama Parate & Khobragade Nikita Imaging appearance: Fat-suppressed, dynamic CEMRI shows initial patchy On MR imaging, they are seen as homogeneous and enhancement followed by homogeneous well-defined intraconal lesions but can also involve enhancement in the delayed phase. Imaging the orbital apex or extraconal space (<10%) [3]. they differentials include venous varix and, less often, appear hypointense to fat and isointense to muscle schwannoma. A venous varix shows intermittent on T1-weighted imaging and hyper intense to muscle intralesional flow and exophthalmos on Valsalva and fat on T2-weighted imaging (Fig 1) [4, 5, 6, and maneuver. Schwannomas also appear well- 7]. Micro calcifications (or phleboliths) and orbital circumscribed, iso-hypointense on T1W sequences. bone expansion may be present. These findings are Cavernous hemangioma appear bright on DW images unusual, but best visualized by non-contrast CT with mean ADC values ranging from 1.23×10-3 using bone window algorithms. mm2/s to 1.39×10 -3mm2 /s. Razek et al have MR shows isointense T1 signal, bright T2 signal, dark reported that schwannomas have mean ADC value of internal septations, and a dark circumferential rim 1.92×10-3 mm2/s, which is statistically different that represents a fibrous pseudocapsule [8 and 9]. from that of cavernous hemangioma [10]. A B C Fig 1 Right intraconal and extraconal cavernous hemangioma A. T2 weighted image reveal hyper intense well defined mass in the medial compartment B. T1 fat suppressed image reveal absence of suppression C. Intense enhancement on post contrast T1 image with a flow void within. Choroidal melanoma: These lesions are the most common primary intraocular tumors in adults and the most commonly occurring uveal melanoma. Sixty-five percent of melanomas occur in those older than 50 years. Patients may be asymptomatic. Symptomatic patients may experience a vision loss, photopsia and visual field deficits. Most choroidal melanomas appear as well-defined solid masses at MR imaging. Those that are hemorrhagic or necrotic have varied MR imaging appearances. A B C D Fig 2 Uveal Melanoma – Enhancing(D) altered signal intensity involving lateral and inferior compartment of right eyeball (posterior segment) appearing hyperintense on T1W (A coronal, C axial) and hypointense on T2W image (B). Right optic nerve appears normal. Associated vitreous hemorrhage is seen. Logic Publications @ 2018, IJCMAAS, E-ISSN: 2321-9335,P-ISSN:2321-9327. Page | 60 Logic Publications @ 2018, IJCMAAS, E-ISSN: 2321-9335,P-ISSN:2321-9327. The melanin content causes characteristic comprise10–15% of all orbital tumors [14]. Of all hyperintense signal on T1W and hypo intense signal patients with orbital lymphoma, approximately 70% on T2W MR Images (Fig 2). Because of the to 75% have systemic disease. There is usually an paramagnetic effects of melanin, intensely melanotic insidious presentation of painless proptosis with melanomas have shorter T1 and T2 relaxation times, motility disturbances [15]. Suspicion of malignant producing increased signal intensity on T1-weighted lymphoma is increased in the presence of systemic images and markedly decreased signal intensity on disease, lacrimal duct or gland disease, and bilateral T2-weighted images [11]. disease. More pronounced pigmentation is associated with Retrobulbar lesions may present with decreased poorer prognosis. Unfortunately, amelanotic and ocular motility, proptosis, diplopia, eyelid edema, slightly melanotic melanomas do not show the same chemosis, and pain. Extraocular muscles are rarely signal intensity characteristics. Instead, the signal in invaded and their function is not significantly these lesions may appear isointense on T1-weighted impaired. There is a spectrum of imaging findings images and only slightly hypointense on T2- from a well-defined, round, or lobulated mass to a weighted images, similar to that in choroidal less defined, infiltrative process. Moderate expansion metastases and other tumors of the globe. of the orbital cavity is observed in some cases of Following the administration of contrast material, reactive lymphoid hyperplasia. Aggressive, choroidal melanomas demonstrate moderate to malignant lymphoma, however, can demonstrate strong enhancement. Fat-saturated, high-resolution osseous destruction, although this is rare. CEMRI is ideal for demonstrating small enhancing By CT, lymphoma and pseudotumor have a tumours, associated retinal detachment as well as nonspecific density similar to extra ocular muscles. extra ocular disease. In the absence of history of systemic lymphoma or Erb Eigner etal [12] reported that ocular melanomas other systemic diseases, MR imaging becomes the show marked restricted diffusion with a mean ADC study of choice because of the improved specificity of value of 0.891×10-3 mm2/s. Also, the mean ADC of this technique. On T2 weighted images lymphomas ocular melanoma appears to be statistically appear slightly hyperintense to fat while significant from the mean ADC of retinal detachment pseudotumors are isointense (Fig 3). thereby facilitating diagnosis. This is probably related to a prominent fibrous stroma in the pseudotumors. Pseudotumors usually Lymphoma: show more prominent enhancement with contrast A recent study has reported that orbital lymphoma material, than observed in lymphoma cases. accounts for 55 % of malignant orbital tumors and Lymphomas most commonly involve the showed the greatest rise in annual incidence of superolateral aspect of the orbit and bilateral disease orbital malignancies [13]. Lymphoproliferative is common. Lymphoma can involve virtually any part disorders of the orbit span the spectrum from benign of the orbit, including the lacrimal gland, extraocular (reactive) lymphoid hyperplasia to malignant muscles, lacrimal sac, periorbital fat and retrobulbar lymphoma. Reactive lymphoid hyperplasia tends to fat. Orbital lymphomas typically show very low ADC be a polymorphic subset of cells, whereas values whereas pseudotumors show higher ADC lymphomas demonstrate monoclonality. Patients values. with primary orbital malignant lymphoma