Morphology And Asymmetry Of The Intraparietal Sulcus In Chinese Brain

The Intraparietal Sulcus(IPS)located on the lateral side of the brain is a long and deep antero-posterior sulcus,parallel to the intrahemispheric fissure.It is originated from the post-central sulcus,terminated at the transverse-occipital sulcus and separates the superior parietal lobe from the inferior parietal lobe.Neuroimaging studies have suggested that IPS is sophisticated,and shows a great relationship to the human cognition,including attention,notation and simple arithmetic ability.Meanwhile,the IPS can be used as an operative corridor for some major operations in the lateral ventricle trigone.Thus,the accurate recognition and quantitative understanding of the IPS in the three-dimensional space are of great significance to the image diagnosis and the minimally invasive surgery.In 1866,the IPS was first identified and named by Turner.After that,several researchers have investigated the morphologies of the IPS.Almost all the early researchers have done their researches of the IPS using the cadaver specimens,combined with manual measurement and visual observation.But during the process of specimen processiig,the deformation and atrophy of the specimen always made a certain error between the specimen morphology and the actual morphology.Besides,the whole brain specimen processing requires a high degree of anatomical technology for researchers,and it is difficult to process the specimen's whole brain,so the number of cadever researches cases are often limited due to the difficulty in obtaining the specimen.With the development of neuroimaging and computer technology,our researches on brain structures become more and more in-depth.Nowadays,our study of brain structures are not constrained to the specimen only,vivo-section researches become possible.The application of high-resolution imaging data not only makes the sample size no longer limited,but also makes it feasible to study the repeatability and dynamics of living samples.The 3D reconstruction and morphological measurement by software are less affected by human factors.In addition,the standardized data are comparable to each other.As most previous studies were based on western data,the morphological characteristics and specific parameters of the Chinese IPS need to be further studied.In this study,with advanced 3D reconstruction methods,we analyzed the morphology,branches,types,sex dimorphism and side asymmetry of Chinese human cerebrum using high resolution MR imaging data of Chinese adults.Purpose:Based on neuroimaging and 3D reconstruction methods,the morphology of IPS was studied,including its cross section representation in Talairach coordinate system,three-dimensional anatomical model,classification,and branches of the IPS.The morphological parameters of the IPS were measured,including the top length(TL),bottom length(BL),average width(AW),average depth(AD)and so on.The gender dimorphism and lateral asymmetries of the IPS were studied using statistical methods.Material and methods:In this study,107 normal right-handed Chinese young adults(male 63,14-20 years old;female 44,15-20 years old;average age:17.2)whose age and sex matched were selected.The 3.0T GE magnetic resonance scanner was used for scanning to obtain high resolution 3DFSPGR axial position brain MRI data.The MRI data was processed by Brain VISA software pipeline.Firstly,the original image was pre-processed into isotropy,and the voxel of each image was 0.78mm*0.78mm*0.78mm;then,the non-brain tissue such as skull,muscle and etc were removed by the automated Brain VISA pipeline.After that,the MRI was standardized to the Talairach coordinate system to control the effect of individual differences in spatial location and brain size.Then the bias correction step is carried out to eliminate the inconsistency in the image acquisition process.After the bias correction step,the gray matter,white matter and cerebrospinal fluid were divided by fuzzy classifier.Then,the pipeline automated identifing the cerebral hemisphere and cerebellum,and reconstruct the main cerebral sulci.After the reconstruction step,the cerebral sulci were automatically labeled.As one of the main cerebral sulci,the three-dimensional model of the IPS was identified and reconstructed.The last step is to correct the automatically labeled sulci manually.Then,we obeserved the morphological features of the IPS,and classified the IPS types in detail according to the morphological characteristics,the branches were determined during this period.The length,width and depth of the IPS were measured by the plug-in RII of BrainVisa software,and the gender and lateralization differences of the morphological parameters of the IPS were analyzed using statistical methods.Results:1.In the Talairach coordinate system,the continuous cross section morphology of the IPS is consistent with that of the 3D reconstruction,the continuity,branches and classification of the IPS observed in the continuous section are consistent with the observed results after 3D reconstruction;2.According to the continuity of the IPS on cortical surface,it can be divided into three types:continuous,two-segments and three-segments;3.The position relationship between the IPS and the adjacent cerebral sulcus(postcentral sulcus and transverse-occipital sulcus)can be divided into four types:none-connection type,true connective type,pseudo connective type and transfixion type;4.The intraparietal sulcus mainly has three branches:the sulcus of Brissaud,anterior intermediate parietal sulcus of Jensen and posterior intermediate parietal sulcus.The three main branches are all related to the complexity of the intraparietal sulcus and sometimes do not appear at the same time;5.The morphology parameters of the IPS1)Gender differences:After the spatial normalization,the TL,BL,AD,W of bilateral IPS were all observed larger in males than females,but they all have none statistical significance(P>0.05).2)Bilateral differences:After the spatial normalization,the TL,BL and AD of the left hemisphere IPS in males are larger than the right hemisphere(P<0.05);the TL and BL of the left hemisphere IPS in the females are larger than right hemisphere(P<0.05).Conclusion and significance:Brain VISA-4.6.0 can efficiently reconstruct almost all the first and part of the second cerebral sulci,providing strongly support for the researches on the cerebral sulci.The morphology of the IPS is complexed and changeable,there are some differences in the distribution of the left and right brain branches of the IPS,and some morphological parameters of the IPS have some differences in sex and lateralization,which may relate to functional asymmetry.The morphology study of the IPS can provide some preferences of the exploration of the morphometry-function relationship,and provide an anatomy base for the transtrigone lateral ventricle clinical operation which takes the IPS as the operation corridor.