Investigation of the alteration of gray matter volume in children with mental retardation with the optimal voxel-based morphometry / 中华放射学杂志

ABSTRACT

Objective To detect brain structural difference between children with unexplained mental retardation and children with typically normal development. Methods The high-resolution magnetic MR imaging were obtained from 21 children with unexplained mental retardation and 30 age-matched control children without intellectual disabilities. Voxel-based morphometry analysis with an optimization of spatial segmentation and normalization procedures were applied to compare differences of gray matter volume between the two groups. The total and regional gray matter volume were compared between the two groups with independent t test. Meanwhile, correlation was conducted to analyze the relationship between the total gray matter volume and intelligence quotient (IQ) with partial correlation test. Results The total gray matter volume was significantly increased in the mental retardation children [(1. 012 ±0. 079) × 106 mm3]in relative to the controls [(0. 956 ± 0. 059) × 106 mm3, t = - 2. 80, P ＜ 0. 05]. Compared to controls,children with unexplained mental retardation showed significantly increased gray matter volume in different regions, including the bilateral thalami, the bilateral superior frontal gyri, the bilateral gyri rectus, the bilateral temporal poles, the right inferior frontal gyrus, right parahippocampal gyrus and the right cerebellum. No correlation was detected between the total gray matter volume and IQ in children with mental retardation (r = 0. 078 ,P ＞ 0. 05). Conclusions VBM would detect the gray matter abnormalities that were not founded in routine MR scanning. The increase of gray matter volume in the frontal-thalamus network might indicate the delayed maturation of the brain development. This might be one of the causations of mental retardation in children.