Diffusion tensor imaging of the pediatric optic nerve: intrinsic and extrinsic pathology compared to normal controls.

PURPOSE To establish normative magnetic resonance diffusion tensor imaging (MRDTI) data in the pediatric optic nerve and compare to pathologic conditions both intrinsic and extrinsic to the anterior optic nerve pathway. MATERIALS AND METHODS A retrospective analysis of MRDTI at 3.0T in children ages 0-18 with both normal imaging studies and with pathologic conditions either arising from the optic nerves or exerting mass effect on the anterior optic pathways was performed. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were obtained within the posterior part of the intraorbital optic nerves. Statistical analysis compared normal controls to optic pathway lesions. RESULTS Lesions intrinsic to the optic nerve including septo-optic dysplasia and optic nerve glioma demonstrated statistically significant reductions in FA and increases in ADC values. There was no statistically significant difference in FA or mean diffusivity between the normal controls and patients with lesions extrinsic to the optic nerve but exerting mass effect on the visual pathway. CONCLUSION MRDTI is a feasible technique for evaluating the optic nerves in pediatric patients. It may play a role in presurgical planning by demonstrating integrity of the visual pathway in patients with resectable lesions, allowing for minimization of morbidity associated with vision loss.