Measurement of the diameter of the cochlear nerve and the age-variation in normal hearing children using MRI / 中华放射学杂志

ABSTRACT

Objective To measure the diameter of cochlear nerve(CN) in normal hearing children with different ages,and evaluate the diameter variations with age.Methods A total of 156 normal-hearing children were assessed with 3D-FIESTA sequence scanning of the inner ear.All the subjects were divided into 13 groups according to age,witha group of ≤6 months,a group of ≤1 year,and 11 groups from one year to 12 years.Each group had 12 cases,including 6 boys and 6 girls.The diameter of CN was measured at the entrance of the cochlea,the middle of internal auditory canal(IAC) and the fundus of IAC respectively on the axial and oblique sagittal images of 3.0 T MRI by two independent observers.The average values measured by them were the final results.The intraclass correlation coefficient was used to determine the consistency between the two independent observers.The t test was used to access differencesin CN diameter by sex and sides.One-way analysis of variance(ANOVA) and two-way ANOVA were used for comparisons among different groups.Spearman correlation coefficient was applied to find a correlation between the CN diameter and age.Results The diameters of normal-hearing children's CN at the middle of the IAC,IAC fundus and the entrance of the cochlea were (1.12 ± 0.08),(1.05 ± 0.06),(0.87 ± 0.14) mm respectively,and there was significant difference among the three measuring points (F=527.57,P＜0.05).The diameters of the CN had no significant differenc (P＞0.05) in age-groups,gender and sides(P＞0.05),and there was no correlation between the diameters of normal children's CN and age.Conclusions The diameters of normal-hearing children's CN change with different points of the IAC,of which the maximum value is at the middle of the IAC,followed by the IAC fundus,and the entrance of the cochlea is at the minimum,more over the normal size doesn't change with age.