Detection of optic nerve involvement in retinoblastoma with enhanced computed tomography.

PURPOSE: The study was designed to evaluate the value of enhanced computed tomography (CT) as a non-invasive test in the detection of optic nerve invasion in retinoblastoma.
METHODS: Nineteen eyes in 17 consecutive retinoblastoma patients underwent CT studies performed with high spatial resolution (512 x 512) and 1.5 mm sections, both with enhancement and without enhancement. If the central retinal vessels (CRV) were subjectively visualised with intravenous enhancement, the optic nerve was considered to be free of retinoblastoma. Nineteen enucleated globes were processed for histopathology, and the optic disc and nerve examined with light microscopy for the presence or absence of tumour and the level of involvement.
RESULTS: The correlation between the visualisation of CRV and the presence or absence of optic nerve involvement histopathologically was found to be highly significant (p = 0.0006, Fisher exact test).
CONCLUSION: In high spatial resolution CT with enhancement and 1.5 mm or thinner sections, non-visualisation of the CRV appears to be a reliable indicator of optic nerve invasion with retinoblastoma.