Optic pathway measurements on MRI: normal values in the pediatric population

Background Different pathologies can affect the optic pathway structures in children, and early detection of these pathologies requires knowledge of their normal measurements. This study aimed to establish a standardized method for measuring the optic pathway structures and report their normal values in children up to six years of age using brain MRI. Methods We retrospectively analyzed the brain MR images of pediatric patients from infants to six years of age; scans that were interpreted as normal were included in the study. Axial T2-weighted images were used for optic nerve (intra-orbital, pre-chiasmatic) and optic tract measurements. Coronal T2-weighted images were used for optic chiasm measurements. Patients were stratified into six age groups for analysis. Results A total of 104 MRI studies of the brain were included; there were 65 males and 39 females. The mean age of all the patients was 26 ± 12 months. An increase in diameter was observed with age for all measurements. There is a strong positive correlation between age and mean diameter of each of the intra-orbital optic nerve ( r = 0.670), pre-chiasmatic optic nerve ( r = 0.703), optic tract ( r = 0.693), as well as the height of the optic chiasm ( r = 0.716). Conclusions Using axial and coronal brain MRI, we suggested standardized locations for measuring the optic pathway structures and reported their normal values in children from birth to 6 years of age.