Computerized tomography of malignant melanomas of the choroid

Twelve histologically verified choroidal melanomas, 15 normal fellow eyes and 4 simulating lesions (vitreous haemorrhage, choroidal haemorrhage, retinal detachment and choroidal detachment) were CT-scanned before and after intravenous contrast media (maximal attenuation in the tumours were estimated from a computerized curve corresponding to a line placed from the center of the eye, through the tumour to the outside of the bulb). The melanomas showed significantly higher precontrast attenuation (54 HU) than the control eyes (17 HU) measured in symmetrical points. Enhancement was registered in all the tumours (mean = 22 HU, P less than 0.01), but not in the control eyes. Among the simulating lesions, the retinal detachment enhanced after contrast. Indications for CT-scan of intraocular processes are diagnostic doubt in opaque media and suspected extrabulbar extension. A patient with verified, disciform organised subretinal haemorrhage scanned after the primary series showed contrast enhancement comparable to the malignant melanoma series. Also 'CT-positive' tumour eyes have to be observed over a period.