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This study investigated white matter integrity in young children with autism using diffusion tensor imaging (DTI). Twenty-two children with autism, mean age 3:2 years, and 32 controls, mean age 3:4 years, participated in the study. Tract-based spatial statistics (TBSS) revealed white matter abnormalities in several distinct clusters within the genu and body of the corpus callosum (CC), left superior longitudinal fasciculus (SLF) and right and left cingulum (Cg). TBSS-VOIs analysis was performed in the clusters where differences in fractional anisotropy (FA) were detected to investigate the relationship between changes in FA and diffusivity indices. In all VOIs, increase in FA was caused by a decrease in radial diffusivity (Dr), while no changes in axial diffusivity (Da) or mean diffusivity (MD) were observed. Tractography analysis was applied to further study the CC, SLF, and Cg. Witelson parcellation scheme was used for the CC. Significant increase in FA was seen in children with autism in the mid-body of the CC as well as in the left Cg. It is suggested that such abnormal white matter integrity in young children with autism may adversely affect connectivity between different brain regions and may be linked to some of the behavioral impairments apparent in autism.

Our study demonstrated that dedicated neurosonography is equal to MRI in the diagnosis of fetal brain anomalies. In most of the cases MRI confirmed the ultrasonographic diagnosis; in a minority of cases each modality provided additional/different information. The major role of MRI was in reassurance of the parents regarding the presence or absence of brain anomalies.

Purpose:To evaluate the sensitivity of high b value diffusion weight magnetic resonance imaging (DWI) in detecting normal white matter maturation, compare it to conventional diffusion tensor imaging (DTI), and to obtain normative quantitative data using this method. Materials and Methods:High b value DWI (b max ϭ 6000 sec/mm 2 ) using q-space analysis and conventional DTI (b ϭ 1000 sec/mm 2 ) were performed on 36 healthy subjects aged 4 months to 23 years. Fractional-anisotropy (FA), apparent-displacement, and apparent-probability values were measured in all slices and in six regions of interest (ROIs) of large fiber tracks. Values were correlated with each other and with age using regression analysis.Results: FA, displacement, and probability indices from all slices were highly correlated with each other (r Ͼ 0.87, P Ͻ 0.0001) and with age (r Ͼ 0.82, P Ͻ 0.0001). All age-related changes in the six pre-determined ROIs were best fitted by mono-exponential functions. Changes in the splenium extended to a later age when compared with the genu of the corpus-callosum, while the centrum semi-ovale demonstrated the latest changes with age. Conclusions:High b-value DWI and DTI showed changes in white matter from infancy through adulthood. However, high b-value detects a signal that is likely to originate mainly from the intra-axonal water population, and thus may represent different aspects of development and different sensitivity to pathology. BRAIN DEVELOPMENT IS a complex process that proceeds in an orderly fashion throughout the postnatal phase and continues into adulthood (1-3). White matter maturation is one element of brain development and is considered essential for normal function and cognitive maturity (4,5). Effective brain function requires integration of information from segregated regions and thus depends on the structural properties of the connecting pathways, including axon diameter and the thickness of the insulating myelin sheet. In vivo volumetric measurements show that white matter volume increases at least up to the third decade of life (6,7). Myelination is one of the main processes of brain development and is a continuous, region-specific process (1,2,6), though its mechanism and exact time course are not fully understood. Indicating the critical time windows of white matter changes throughout development might shed light on the pathogenesis of several white matter and developmental disorders. For example, in a white matter disorder such as leukodystrophy normal brain development is hindered due to malformation of the myelin sheet (2,8). However, the earliest developmental stage that might be critical for therapeutic intervention has yet to be established.At present, magnetic resonance imaging (MRI) provides the most sensitive in vivo method to study white matter maturation (1-3). Developmental changes give rise to changes in T 1 and T 2 relaxation times, spectroscopic metabolite ratios, magnetization transfer ratio, and diffusion anisotropy in the white matter. In routine MR examinations, T 1 and...