Magnetic resonance imaging features of the optic nerve in enucleated retinoblastoma patients

Abstract

Purpose : The aim of this retrospective review was to determine the role of gadolinium-enhanced magnetic resonance imaging in the assessment of optic nerve of retinoblastoma patients post-enucleation by detecting signs of contrast enhancement and/or thickening along the cut end of the nerve.

Methods : Eligible patients underwent enucleation for retinoblastoma between January 2008 and December 2015. Overall, 90 enucleated eyes for 88 patients were included. Post-contrast MRI of the orbit was performed both pre-enucleation, for evaluation of optic nerve and trilateral disease, and post-enucleation for routine screening. The primary outcome measures were contrast enhancement along the cut end of the optic nerve, abnormal optic nerve thickening, presence of orbital disease, and/or trilateral retinoblastoma post-enucleation. Based on radiologist assessment, optic nerve enhancement was categorized into 3 subgroups: mild, moderate, or severe. Tumor extension into the optic nerve on histopathology was also assessed and categorized as pre- or post-laminar invasion.

Results : Overall, 41 of 50 eyes (82%) of post-enucleation patients demonstrated contrast enhancement along the cut end of the optic nerve post-enucleation at a mean interval of 10 months. Of these, 20 demonstrated moderate enhancement and 7 mild; the severity of enhancement was not described for 14 patients. The enhancement was noted to be stable or resolved on follow-up imaging. Among the 88 patients, 38 patients received systemic chemoreduction with CEV pre-enucleation; there was no association between chemotherapy administration and optic nerve enhancement. Histopathologic post-laminar optic nerve invasion was reported in 6 eyes and pre-enucleation optic nerve enhancement was detected in 3 of these eyes. No child required a biopsy secondary to optic nerve findings. None of these patients were found to have subsequent orbital or metastatic disease at last exam under anesthesia (average 13 months, range 1-59) or last follow-up visit (average 29 months, range 1-71).

Conclusions : Optic nerve contrast enhancement on follow-up MRI post-enucleation for retinoblastoma is a common finding and appears to be consistent with normal post-surgical scarring and granulation tissue, and not active tumor. The presence or absence of post-enucleation enhancement did not correlate with pre-enucleation chemotherapy or the presence of optic nerve invasion on histopathology.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.