Study Of Brain Structure In Children With Intellectual Disability By Magnetic Resonance Three-dimensional T₁ Weighted Imaging

Objective:To explore whether there are specific imaging features of brain structure in children with non-syndromic intellectual disability（NS-ID）based on three-dimensional T₁-weighted imaging,and to analyze the relationship between brain structure development and intellectual disability,so as to provide theoretical basis for studying the neuropathological mechanism and clinical diagnosis of children with intellectual disability.Methods:A total of 49 cases of children with intellectual disability who complained of intellectual disability in the Department of Pediatrics of The Third Affiliated Hospital of Zunyi Medical University from January 2019 to October 2020 were evaluated with the second edition of Wechsler Intelligence scale for Children.Them met the requirements of intellectual disability and brain MRI scanning（intellectual disability group,referred to as ID group）,33 males and 16 females,including 19 cases of language deficit（LD）group and30 cases of common deficit（CD）group.At the same time,34 healthy control（HC,20males and 14 females）children were recruited during this period with matching sex,age and education level and brain MRI images met the requirements.The German Siemens Skyra 3.0T high field magnetic resonance scanning system was used to obtain T₂-FLAIR and 3D-T₁WI images data.The images were preprocessed by VBM-DARTEL toolkit in SPM 8 software under Matlab R2013b working platform.General linear model was used to compare the differences of gray matter,white matter volume and whole brain volume among ID group,LD group,CD group and matched HC group by two-sample t-test.There were significant differences in terms of P<0.001 FDR correction and nuclear>20 voxels.SPSS software was used to analyze the correlation between abnormal brain volume and IQ score and clinical indexes in each group.Results:There was no significant difference in sex,age,education level and handedness between ID group,LD group,CD group and matched HC group,respectively.The total volume of gray matter,white matter and whole brain volume of children with intellectual disability in the three groups were lower than those of HC group.（1）Compared with HC group,ID group showed increased volume in left orbital medial superior frontal gyrus,left medial superior frontal gyrus,right medial superior frontal gyrus,right cuneus lobe and bilateral supplementary motor area and showed reduced volume in the right middle temporal gyrus.Correlation analysis showed that total gray matter volumes（r=0.400,0.337 and 0.411 respectively）and the volume of gray matter in right middle temporal gyrus（r=0.448,0.468 and 0.446 respectively）were positively correlated with FSIQ,VIQ and PIQ scores in all children;the volume of gray matter were negatively correlated with FSIQ,VIQ and PIQ scores in right cuneus lobe（r=-0.416,-0.377 and-0.409 respectively）and left orbital medial superior frontal gyrus（r=-0.368,-0.346,-0.364 respectively）.（2）Compared with the matched HC group,LD group showed increased volume in the right cuneus lobe and left calcarine fissure and surrounding cortex.Correlation analysis showed that the volume of gray matter in the right cuneus lobe（r=-0.590,-0.493 and-0.648respectively）were negatively correlated with FSIQ,VIQ and PIQ scores in all children.（3）Compared with matched HC group,CD group showed increased volume in the left orbital medial superior frontal gyrus,left medial superior frontal gyrus,left inferior orbital frontal gyrus,left triangular inferior frontal gyrus and left supplementary motor area.Correlation analysis showed that total gray matter volumes（r=0.483,0.444 and 0.500 respectively）were positively correlated with FSIQ,VIQ and PIQ scores in all children;the volume of gray matter in left inferior orbital frontal gyrus（r=-0.258,-0.270 and-0.270 respectively）,left orbital medial superior frontal gyrus（r=-0.418,-0.411 and-0.396 respectively）and left supplementary motor area（r=-0.412,-0.377 and-0.411 respectively）were negatively correlated with FSIQ,VIQ and PIQ scores.Conclusion:（1）Children with NS-ID have specific imaging features of brain structure,that is,the local gray matter volume of frontal lobe and occipital lobe is increased,and some brain regions are correlated with IQ score,which may be the anatomical basis of cognitive impairment and adaptive behavior impairment in children with intellectual disability.（2）There may be differences in the regional distribution of gray matter volume changes in children with different types of NS-ID.（3）The trajectory of brain gray matter development in children with intellectual disability may be abnormal.