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Year : 2006  |  Volume : 16  |  Issue : 4  |  Page : 683-688
CT evaluation of proptosis


Department of Radio-diagnosis,Dr. S.N. Medical College & Associated Group of Hospitals, Jodhpur , Rajasthan, India

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Date of Submission17-Aug-2006
Date of Acceptance10-Nov-2006
 

   Abstract 

Objectives: To analyse the diagnostic role of CT scan in evaluation of proptosis Material and Methods: 50 patients presenting with proptosis were evaluated by CT scan. Role of CT was evaluated in defining the cause of proptosis and the nature and extent of the lesions causing proptosis. Results: .The most common lesion causing proptosis were tumours (46%) and infections (28%) followed by inflammation (18%), trauma (6%) and vascular (2%). CT scan findings in relation with the age of the patient, the clinical picture and laboratory investigations were able to give a correct diagnosis in 82% patients. Conclusion: CT scan can be considered as a cost effective, non invasive, reliable diagnostic tool for evaluation of proptosis.

Keywords: CT scan, proptosis

How to cite this article:
Sabharwal K K, Chouhan A L, Jain S. CT evaluation of proptosis. Indian J Radiol Imaging 2006;16:683-8

How to cite this URL:
Sabharwal K K, Chouhan A L, Jain S. CT evaluation of proptosis. Indian J Radiol Imaging [serial online] 2006 [cited 2019 Aug 24];16:683-8. Available from: http://www.ijri.org/text.asp?2006/16/4/683/32299

   Introduction Top


Proptosis is defined as an abnormal protrusion of the eyeball. Owing to the rigid bony structure of the orbit with only anterior opening for expansion, any increase in orbital contents taking place from the side or from behind will displace the eyeball forward. Proptosis can be the result of a myriad of disease processes including infections, inflammations, tumours, trauma, metastases, endocrine lesions, vascular diseases & extra orbital lesions.

The evaluation of proptosis include a detailed clinical history , ocular examination, laboratory investigations & imaging studies .As far as the radiological investigations are concerned , findings on plain radiographs & ultrasonography are not pathognomonic of most of the orbital disease process though some help can be obtained in characterization of lesion in certain cases. Advent of MRI & CT has revolutionized the diagnostic imaging of orbit & its contents. MRI with its superb soft tissue contrast & multiplanar ability provides excellent rendering of orbital anatomy but is limited by lack of wider availability & high cost. On the other hand easy availability and operability, good maintenance and speed makes CT scan an affordable diagnostic tool in orbital diseases under existing circumstances and present set up.


   Material and Methods Top


50 patients of various age groups & both sexes with unilateral or bilateral proptosis were the subjects for the study. Before commencing for CT examination, all the preceding history, clinical, laboratory data were recorded. A CT scanner (SIEMENS SOMATOM AR.T) was used for the study. The technique was to obtain a lateral scannogram with the patient supine and contiguous axial sections with slice thickness of 3 mm and interslice gap of 3 mm were obtained. Coronal 3-5 mm sections were obtained as and when required with the patient in prone position. The scans were obtained both prior to and after administration of non ionic intravenous contrast. All patients with globe protrusion >21mm anterior to the interzygomatic line on axial scans at the level of lens were evaluated .CT findings were correlated with final diagnosis based on clinical, laboratory findings , operative findings , histopathological study or response to treatment.


   Results Top


The patients included were from 2 to 80 yrs. of age. The majority of patients (22%) were between 31-40 yrs. of age. man/woman ratio was 1.08: 1. The most common lesion causing proptosis were tumours and infections. Various lesions causing proptosis are grouped in the table.


   Tumours Top


Lymphomas were the most common orbital tumours. In all four patients lymphoma appeared as homogenously enhancing soft tissue masses in extraconal space with involvement of intraconal space in two patients [Figure - 1]. Extraocular muscles were involved in all patients and Optic nerve involvement was seen in one patient. Eyeball was normal & displaced in all patients. Bone erosion was seen in one patient.

Two patients of retinoblastoma revealed homogenously enhancing masses involving whole of the eyeball. Calcification was seen in both patients while thickening of the Optic nerve with extension up to Optic chiasma was seen in one patient [Figure - 2].

Two patients of rhabdomyosarcoma presented as homogenously enhancing extraconal masses with involvement of extraocular muscles in both patients. Epidural extension was seen in one patient.

Optic nerve sheath meningioma (one patient) appeared as homogenously enhancing intraconal mass with central lucency (Optic nerve) and one patient of malignant melanoma appeared as large heterogeneously enhancing mass infiltrating all extraocular muscles and the eyeball. In one patient, dermoid appeared as hypodense non enhancing extraconal mass with fat density with scalloping of the lateral orbital wall. Hemangioma appeared as hyperdense intraconal mass with moderate enhancement in one patient while a patient of leukemia in our study presented as homogenously enhancing mass with extraconal & intraconal involvement with infiltration of extraocular muscles and the Optic nerve.

Three patients in our study presenting with proptosis were proved to be metastases in the orbit. One of the patients presenting with extraconal masses in superolatateral quadrants in bilateral orbits was proved to be a case of neuroblastoma on abdomen CT. One patient presenting with extraconal mass in the right orbit was shown to have a swelling in the left leg which was proved to be Ewings sarcoma. One patient was a follow up case of Ca breast and was shown to have metastatic extraconal mass in the left orbit.

The most common paraorbital tumor invading the orbit in our study was maxillary carcinoma. In all three patients maxillary carcinoma appeared as heterogeneously enhancing masses involving the maxillary sinus, nasal cavity, ethmoid sinuses, infratemporal fossa with bone destruction and extension into the orbit. Two patients of angiofibroma presented as soft tissue masses with intense homogenous enhancement involving nasal cavity, pterygopalatine fossa, ethmoid sinuses, infratemporal fossa with extension through inferior orbital fissure into the orbit. Intracranial extension was seen in one patient. Esthesioneuroblastoma in a patient appeared as intensely enhancing mass filling bilateral nasal cavities, ethmoid sinuses, maxillary sinuses, and bilateral orbital apices with extension into anterior cranial fossa by eroding the floor of anterior cranial fossa [Figure - 3] while ethmoid osteoma appeared as bone density mass in ethmoid sinuses extending into the orbit in one patient [Figure - 4].


   Infections Top


Amongst nine patients of orbital cellulitis in our study, subperiosteal involvement was the most common seen in six patients with preseptal extension seen in all showing increased density of the soft tissues. Formation of subperiosteal abscess with medial enhancing rim was seen in two patients. Diffuse orbital involvement was seen in two patients with increased density of soft tissues in both intraconal and extraconal spaces. Involvement of the eyeball with uveoscleral thickening was seen in four patients [Figure - 5]. Concurrent ethmoid sinusitis was seen in seven patients and maxillary sinusitis in one patient. One patient presented with soft tissue density in peripheral orbital space with mass in the nasal cavity and ethmoid sinuses with erosion of the medial orbital wall which was proved to be mucormycosis on histopathology.

Amongst five patients of mucoceles of paranasal sinuses invading the orbit, involvement of frontal sinus was most common followed by frontoethmoid involvement. All patients had a non enhancing extraconal cystic mass in superomedial quadrant of the orbit with evidence of expansion of the bone in all and erosion of bone in three patients [Figure - 6]. Optic nerve compression was seen in one patient.


   Inflammation Top


Amongst five patients of Grave's disease, bilateral involvement was seen in four patients and unilateral involvement in one. Extraocular muscle enlargement was seen in all patients with multiple muscle involvement being more common than single muscle involvement. Inferior rectus muscle was most commonly enlarged followed by medial rectus and superior rectus.

In inflammatory pseudotumor of the orbit, unilateral involvement was more common (three patients) than bilateral (one patient). Muscle involvement was seen in three patients with multiple muscle involvement being more common. Muscle enlargement was diffuse involving the tendinous insertions. Lacrimal gland was enlarged in one patient. Soft tissue infiltration of orbital fat was seen in three patients with infiltration up to orbital apex in one patient. Optic nerve was infiltrated in two patients. Eyeball was involved in a patient showing uveoscleral thickening with enhancement.


   Trauma Top


All three patients of orbital trauma had intraorbital haemorrhage (retrobulbar and preseptal). Fracture of the bony orbit was seen in all patients with evidence of haemorrhage in paranasal sinuses in all. There was extradural haematoma in temporal lobe in one patient.


   Vascular Top


In our study there was one patient of carotid cavernous fistula presenting as pulsatile exophthalmos after trauma. CT findings included proptosis, asymmetry and distension of affected cavernous sinus and congestion and asymmetrical dilatation of superior ophthalmic vein [Figure - 7].


   Discussion Top


The most common lesion causing proptosis in our study were tumours (46%).Our findings correlated well with the findings of Masud MZ et al (2006) [1] who described neoplasms (33%) as the most common causes of proptosis in their study. Lymphomas were the most common orbital tumours in our study. Margo CE et al (1998) [2] reported orbital lymphoma to be the most common malignant orbital tumours. The most common paraorbital tumor invading the orbit in our study was maxillary carcinoma similar to that described by Johnson LN et al (1984) [3]. Out of 23 patients of tumours CT diagnosis correlated with the histopathological diagnosis in 18 patients (78.26%). In a study by Usha et al (2005) there was 56.6% correlation between the CT diagnosis and histopathological diagnosis in case of neoplasms (Conference Proceedings: All Indian ophthalmological society: 2005).

Infectious pathology accounted for 28% patients of proptosis in our study while in study by Masud MZ et al (2006) [1] infections accounted for 20% patients of proptosis. CT provided an accurate diagnosis in 88.8% patients of orbital cellulitis in our study. Clary RA et al (1992) [4] analysed the accuracy of CT in orbital cellulitis in children and showed correlation between radiological and operative findings in 84.21% cases.

Graves disease accounted for 10% patients of proptosis in our study compared to the study by M K Narula et al (1994) [5] where Graves disease accounted for 6% patients of proptosis. Inferior rectus muscle was most commonly enlarged followed by medial rectus and superior rectus similar to the study by Murakami Y et al (2001) [6]. Correct diagnosis of Graves disease was made in 4 out of 5 (80%) patients on CT in the present study. In a study by Ozgen A et al (1999) [7] diagnosis of Graves ophthalmopathy was made in 69 of 87 (79%) patients using CT.

Pseudotumor accounted for 8% patients of proptosis in our study compared to the study by M K Narula et al (1994) [5] where pseudotumor accounted for 11% patients of proptosis. Correct diagnosis of pseudotumour was made in 50% patients in our study in view of the non specific radiological findings as stated by Alfred L Weber et al (1999) [8].

Trauma was the cause in 6% patients of proptosis in the present study. Our results are similar to the study done by Masud MZ et al (2006) [1] where trauma was the cause of proptosis in 5% patients.

In our study vascular lesions were the least common accounting for 2% patients of proptosis while in a study by Masud MZ et al (2006) [1] 7 % cases of proptosis were caused by vascular lesions.

In the present study overall CT diagnosis was found to be correct in 41 patients (82%). Our results are similar to the study of Zahir Shah Mahsud et al (2004) [9]. In their study the diagnostic accuracy of CT scan in evaluation of proptosis was 80%. CT scan is highly useful in describing the precise location and extent of the lesion and is fairly accurate in lesion characterization. In view of non specific findings in cases of orbital tumours and pseudotumours, an evaluation of clinical and laboratory data is essential to arrive at a precise diagnosis.


   Conclusion Top


CT is useful to characterize: the precise location of the lesion - the intraconal space (including muscles & Optic nerve), the extraconal space (associated or not to an extra orbital lesion), or the eyeball; the features of the lesion (density, calcification, enhancement.). These findings are helpful to generate a differential diagnosis. CT is also useful to demonstrate the precise extension of the orbital lesion, the involvement of adjacent paranasal sinuses & nasal cavity, the evidence of bone erosion and intracranial extension which helps in pre treatment evaluation & post treatment follow up. To conclude CT scan can be considered as a cost effective, non invasive, reliable diagnostic tool for evaluation of proptosis.

 
   References Top

1.Masud MZ, Babar TF, Iqbal A et al, Proptosis- etiology and demographic patterns. J. Coll. Physicians Surg. Pak. 2006; 16(1): 38-41  Back to cited text no. 1    
2.Margo CE, Mulla ZD, Malignant tumors of the orbit. Ophthalmology 1998; 105: 185  Back to cited text no. 2    
3.Johnson LN, Krohel GB, Yeon EB, Parnes SM, Sinus tumors invading the orbit. Ophthalmology 1984; 91(3): 209-17.   Back to cited text no. 3    
4.Clary RA, Cunningham MJ, Eavey RD, Orbital complications of acute sinusitis- Comparison of CT scan & surgical findings. Ann. Otol. Rhinol. Laryngol. 1992; 101 (7): 598-600  Back to cited text no. 4    
5.Narula M. K. et al, Ultrasound evaluation of proptosis. IJRI 1994; 4: 203-206  Back to cited text no. 5    
6.Murakami Y, KanamotoT, Tuboi T et al, Evaluation of extraocular muscle enlargement in dysthyroid ophthalmopathy. Jpn J Ophthal. 2001; 45(6): 622-7  Back to cited text no. 6    
7.Ozgen A, Alp MN, Ariyurek M, Tutuncu NB, CanI, Gunalp I, Quantitative CT of orbit in Graves disease. Br. J. Radiol.1999; 72 (860): 757-6  Back to cited text no. 7    
8.Alfred L. Weber, Laura Vitale Romo,Nelson R. Sabates, Pseudotumor of the orbit RCNA Jan 1999; 37:1: 151-166  Back to cited text no. 8    
9.Zahir Shah Mahsud, Suraya Bano, Diagnostic role of CT scan in proptosis in pediatric age group. JPMI 2004; 18: 3: 439-446  Back to cited text no. 9    

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Correspondence Address:
K K Sabharwal
C-86, Shastri Nagar Jodhpur (Rajasthan)
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0971-3026.32299

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    Figures

  [Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7]
 
 
    Tables

  [Table - 1]

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    Abstract
    Introduction
    Material and Methods
    Results
    Tumours
    Infections
    Inflammation
    Trauma
    Vascular
    Discussion
    Conclusion
    References
    Article Figures
    Article Tables

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