Accuracy of preoperative imaging in predicting optic nerve invasion in retinoblastoma: A retrospective study

Purpose: Optic nerve invasion is an important cause of mortality in retinoblastoma. We aimed correlate preoperative imaging and surgical histopathology findings in enucleated eyes with retinoblastoma to determine the efficacy of preoperative imaging in predicting optic nerve invasion in retinoblastoma. Methods: A retrospective review of records of all patients undergoing primary enucleation for retinoblastoma at a tertiary eyecare system between March 2013 and December 2017 with all patients having undergone preoperative imaging, either CT scan or MRI. Data was analyzed statistically to determine the correlation between preoperative CT scan/MRI and histopathology. Results: Totally, 97 eyes of 97 patients were included in the study who underwent primary enucleation for unilateral retinoblastoma. The average age at presentation was 27.8 months with the chief complaint being leukocoria in all the cases. 14 patients (14.43%) had evidence of optic nerve involvement in preoperative imaging. 30 patients had optic nerve invasion on histopathology (laminar and retrolaminar). Spearman's rank correlation test revealed a significant correlation between MRI findings and HP and an insignficant correlation between CT findings and HP. The CT scan had a sensitivity of 20%, specificity of 88.89%, 50% positive predictive value and 66.67% negative predictive value. MRI had a sensitivity of 40%, specificity of 93.55%, positive predictive value of 66.67% and a negative predictive value of 82.86%. Conclusion: MRI showed significant moderate correlation with surgical histopathology for predicting optic nerve invasion in retinoblastoma whereas CT shows insignificant correlation with HPE. Therefore, we recommend MRI for predicting optic nerve invasion in cases of retinoblastoma.