Year : 1984 | Volume
: 32 | Issue : 5 | Page : 359--363
EMI scan in the management of orbital disease
MS Boparai, RC Sharma, B Ranjan, RG Dash
Department of Ophthalmology and Radiology, Army Hospital Delhi Cantt, India
M S Boparai
Department of Ophthalmology, Army Hospital. Delhi Cantt-110 010
|How to cite this article:|
Boparai M S, Sharma R C, Ranjan B, Dash R G. EMI scan in the management of orbital disease.Indian J Ophthalmol 1984;32:359-363
|How to cite this URL:|
Boparai M S, Sharma R C, Ranjan B, Dash R G. EMI scan in the management of orbital disease. Indian J Ophthalmol [serial online] 1984 [cited 2021 Sep 21 ];32:359-363
Available from: https://www.ijo.in/text.asp?1984/32/5/359/27511
Orbit has always posed diagnostic and therapeutic problems to the ophthalmologist. The standard methods of physical examination hardly fetch any useful information. Homogenous tissue in the retro-ocular area is mute to the x-rays, unless the bones are involved. Computer assisted tomography (CAT) in the transverse axial plane developed by Hounsfield at the research laboratories of EMI limited has revolutionised the investigation of patients with intra cranial disease. Modifications of this examination technique have enabled the study of the retro-ocular tissues of the orbit.
CAT scan has been carried out in 22 cases of unilateral proptosis. The help it has rendered in the managment of these cases and limitations are being presented.
METHODS AND MATERIAL
22 cases of unilateral proptosis after routine work up were subjected to computer assisted axial tomography. Injection of 20 ml Conray 420 (Sodium lothalamate) was given to enhance the density of the abnormal tissue to make differentiation from normal structures easier. Scan was done to find out the presence or absence of a tumour mass and to find out its situation and extent to plan the surgical approach. Before undertaking the scan, all these cases had orbital venography done by the frontal route to compare the two investigations.
In 19 cases (86.4%) a mass was found in the retro-ocular area. 3 cases (13.6%) showed no mass even though the proptosis was present. They proved to be cases of dysthyroid proptosis. 15 cases in which the mass was present were subjected to surgery by the appropriate route and diagnosis was made histologically. However 4 cases did not agree for surgery and therefore a definitive diagnosis could not be arrived at.
[Table 1] shows the results of 22 cases of proptosis subjected to CAT scanning. Venography confirmed the presence of a space occupying lesion in 16 cases (72.8%). The following selected cases in which scan was followed by surgery illustrate the useful-ness of the technique.
Case No. 1. HS a 38 years male had slow growing proptosis of right eye of 3 years duration. There was gradual fall of vision and proptosis at the time of examination was 6 mm [Figure 2]a. Disc was choked going on to atrophy. CAT scan showed a well circumscribed tumour in the muscle cone extending towards the medial wall of the orbit [Figure 2]b. Venography had shown expansion of the parallelogram with an abnormal draining vessel. A clinical diagnosis of haemangioma was made and tumour was removed by antero-medial orbitotomy. Histopathlogy confirmed the diagnosis of cavernous haemangioma.
Case No. 2. HST a Hindu male aged 45 years had right side axial proptosis of 5 mm which had progressed over the last 2 years [Figure 3]a. Optic disc was oedematous. No mass was palpable and conventional radiology was negative. Orbital venography showed an intraconal mass. CAT scan confirmed the presence of the mass jutting against the globe [Figure 3]b. A lateral orbitotomy was performed and a retrobulbar lymphoma 20X 15 mm was found adherent to the globe and optic nerve, part of it was removed. The lesion showed complete resolution following radiation as seen by a follow up CT scan.
Case No. 3. KSR a Hindu male of 23 years had 8 mm proptosis of 3 years duration with the eye pushed down and out. Orbit was explored by medial as well as lateral route as ultrasound gave an equivocal suggestion of a mass in the orbital apex. However no mass was found on surgery. CAT scan after a - year showed a mass placed at the apex of the orbit and along its medial wall extending intracranially [Figure 4]. A transfrontal craniotomy was undertaken and a meningioma was removed partially. There was a recurrence after one year as shown by the repeat scan.
Case No. 4. MM a Hindu male aged 35 years had slow growing proptosis. There was occasional pain with diplopia. Eye was proptosed by6-7 mm [Figure 5]a. Venography showed a blocked superior ophthalmic vein. CAT scan showed a doubtful tumour mass [Figure 5]b. As the extent of the mass was not definite a comupterised coronal tomography was requested. This showed the tumour mass to be enveloping the rear part of the globe and antero lateral orbit. Biopsy showed the mass to be a pseudo tumour which responded to systemic steroids partially. An excision was done by lateral orbital route which reconfirmed the diagnosis.
Case No. 5. WUK a 35 years Muslim male had painless left proptosis of 5 mm. Venography findings were not conclusive. CAT scan showed no mass. Thyroid work up showed it to be a dysthyroid proptosis due to raised T4 levels.
The first essential thing in a case of proptosis is to establish the presence of a tumour mass. It was possible in 19 (83.4%) cases by CAT scan as against 16(72.8%) by venography. This shows a marginal superiority of CAT scan in establishing the presence of a tumour mass over orbital venography. However the two investigations should be taken as complimentary to each other. Orbital Venography therefore has a role in those places where facilities for CAT scan are not available.
The selected case examples amply emphasise the wide spectrum of diseases that can be detected. Case No 4 in which the extent of the tumour mass could not be correctly gauged by axial of the tumour mass could not be correctly gauged by axial tomography highlights the importance of doing coronal tomography also wherever required. A combination of axial and coronal tomography gives a near three dimensional idea about a space occupying lesion. CAT scanning not only facilitates early diagnosis but may provide an index against which the efficacy of surgical treatment and radio therapy can be assessed. This is borne out by case No 2 and 3.
The negative scan in patients presenting with proptosis (3 cases in this study) is also of value as it gives a direction for further investigations to find the cause of proptosis. These cases were found to be dysthyroid. Negative results in dysthyroid proptosis have also been reported.
The exact location of tumour mass within the orbit is important to plan surgical approach to reduce the surgical trauma to the minimum (case No 1-4). Extension of a tumour mass from the orbit to the cranium and vice versa is also shown and helps decide the appropriate approach.
Mistakes in the interpretation of this new x-ray technique have to be guarded against and the investigation should be considered complimentary to other investigations of the orbit and not a replacement for the investigations such as venography, tomography and ultrasound scanning.
Results of CAT scanning in 22 cases have shown a success rate of 83% which is a little better than orbital venography (72%). The presence, extent and exact location of the tumour mass can be found. This non invasive investigation is complimentary to venography.
|1||Hounsfied G.N., 1973. Brit. J. Radiol.46: 1016|
|2||Perry B.J. and Bridges C., 1973. Brit. J. Radiol., 46: 1048|
|3||Gawler J., Sander M.D., Bull J.W.D., du Bonlay G and Marshal J., 1974. Brit. J. Ophthalmol 58: 571|