Lack of correlation between the histologic and magnetic resonance imaging results of optic nerve involvement in eyes primarily enucleated for retinoblastoma.

PURPOSE: To correlate the histologic and magnetic resonance imaging results of the optic nerve in eyes primarily enucleated for retinoblastoma.
DESIGN: Retrospective, clinicopathologic correlation. PARTICIPANTS: Sixty-seven consecutive patients with retinoblastoma who underwent primary enucleation.
METHODS: The histologic results of 67 eyes from 67 patients with retinoblastoma who underwent primary enucleation between March 1997 and January 2008 were studied for evidence of optic nerve invasion. Two neuroradiologists independently reviewed available preoperative magnetic resonance imaging studies with special emphasis on nonenhanced T2-weighted and gadolinium-enhanced T1-weighted imaging for evidence of optic nerve invasion. A weighted kappa statistic was used to assess agreement between observers. MAIN OUTCOME MEASURES: Correlation between neuroradiologists and histologic results.
RESULTS: Of the 67 eyes studied, 60 had preoperative magnetic resonance images, 58 of which were deemed appropriate for review by both neuroradiologists. Review of the histologic results showed optic nerve involvement in 62 (93%) of 67 eyes: 28 prelaminar (42%), 24 laminar (36%), and 10 postlaminar (15%). On review of the magnetic resonance scans, the first neuroradiologist identified optic nerve involvement in 57 (95%) of 60 eyes: 26 prelaminar (43%), 10 laminar (17%), and 11 postlaminar (18%). The second neuroradiologist identified optic nerve involvement in 46 (77%) of 60 eyes: 33 prelaminar (55%), 9 laminar (15%), and 4 postlaminar (7%). Moderate agreement existed between neuroradiologists (kappa, 0.55). Poor and fair agreement existed between each of the 2 neuroradiologists and histologic results, respectively (kappa, 0.29 and 0.17). Exophytic tumors showed the greatest disparity (kappa, -0.20 and -0.13) between magnetic resonance imaging and histologic results.
CONCLUSIONS: Limited correlation was found between magnetic resonance imaging and histologic results in assessing optic nerve invasion in eyes with retinoblastoma. Magnetic resonance imaging using routine imaging technologies, although useful in the evaluation of retinoblastoma, has limited usefulness in assessing the exact extent of optic nerve invasion; high-risk features of retinoblastoma such as postlaminar invasion remain best defined by histologic analysis. This study demonstrates that the interpretation of optic nerve involvement by a radiologist should not be the determining factor to defer enucleation in favor of neoadjuvant therapy.