Enhanced Topological Network Efficiency in Preschool Autism Spectrum Disorder: A Diffusion Tensor Imaging Study

Background: The functional mechanism behind autism spectrum disorder (ASD) is not clear, but it is related to a brain connectivity disorder. Previous studies have found that functional brain connectivity of ASD is linked to both increased connections and weakened connections, and the inconsistencies in functional brain connectivity may be related to age. The functional connectivity in adolescents and adults with ASD is generally less than in age-matched controls; functional connectivity in younger children with the disorder appears to be higher. As the basis of the functional network, the structural network is less studied. This study intends to further study the pathogenesis of ASD by analyzing the white matter network of ASD preschool children.Materials and Methods: In this study, Diffusion Tensor Imaging (DTI) was used to scan preschool children (aged 2–6 years, 39 children with ASD, 19 children as controls), and graph theory was used for analysis.Result: Enhanced topological network efficiency was found in the preschool children with ASD. A higher nodal efficiency was found in the left precuneus, thalamus, and bilateral superior parietal cortex, and the nodal efficiency of the left precuneus was positively associated with the severity of ASD.Conclusion: Our research shows the white matter network efficiency of preschoolers with ASD. It supports the theory of excessive early brain growth in ASD, and it shows left brain lateralization. It opens the way for new research perspectives of children with ASD

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes with an MT-TL1 m.3243A>G point mutation: Neuroradiological features and their implications for underlying pathogenesis

ObjectiveMitochondrial encephalomyopathy with lactic acidosis and stroke−like episodes (MELAS) is one of the most common inherited mitochondrial disorders. Due to the high clinical and genetic heterogeneity of MELAS, it is still a major challenge for clinicians to accurately diagnose the disease at an early stage. Herein, we evaluated the neuroimaging findings of MELAS with an m.3243A>G mutation in MT−TL1 and analyzed the possible underlying pathogenesis of stroke-like episodes.Materials and methodsFifty-nine imaging studies in 24 patients who had a confirmed genetic diagnosis of m.3243A>G (MT-TL1; tRNALeu) associated with MELAS were reviewed in our case series. The anatomic location, morphological features, signal/intensity characteristics and temporal evolution of lesions were analyzed on magnetic resonance imaging (MRI), and computed tomography (CT) images. The supplying vessels and metabolite content of the lesions were also evaluated by using MR angiography (MRA)/CT angiography (CTA), and MR spectroscopy (MRS), respectively.ResultsThe lesions were most commonly located in the posterior brain, with 37 (37/59, 63%) in the occipital lobe, 32 (32/59, 54%) in the parietal lobe, and 30 (30/59, 51%) in the temporal lobe. The signal characteristics of the lesions varied and evolved over time. Bilateral basal ganglia calcifications were found in 6 of 9 (67%) patients who underwent CT. Cerebral and cerebellar atrophy were found in 38/59 (64%) and 40/59 (68%) patients, respectively. Lesion polymorphism was found in 37/59 (63%) studies. MRS showed elevated lactate doublet peaks in 9/10 (90%) cases. MRA or CTA revealed that the lesion-related arteries were slightly dilated compared with those of the contralateral side in 4 of 6 (67%) cases.ConclusionThe imaging features of MELAS vary depending on the disease stage. Polymorphic lesions in a single imaging examination should be considered a diagnostic clue for MELAS. Stroke-like episodes may be involved in a complex pathogenetic process, including mitochondrial angiopathy, mitochondrial cytopathy, and neuronal excitotoxicity

Diffusion Tensor Imaging for Evaluating Biliary Atresia in Infants and Neonates.

Preliminary studies have shown that diffusion tensor imaging (DTI) is helpful in evaluating liver disorders. However, there is no published literature on the use of DTI in the diagnosis of biliary atresia (BA). This study aimed to investigate the diagnostic value of the liver average apparent diffusion coefficient (ADC) and fractional anisotropy (FA) measured using DTI for BA in neonates and infants.Fifty-nine patients with infant jaundice were included in this study. DTI was performed with b factors of 0 and 1000 s/mm2. Liver fibrosis in the BA group was determined and graded (F0, F1, F2, F3, F4) based on the pathological findings. Statistical analyses were performed to determine the diagnostic accuracy of DTI for BA.The ADC value was significantly lower in the BA group [(1.262±0.127)×10-3 mm2/s] than in the non-BA group [(1.430±0.149)×10-3 mm2/s, (P<0.001)]. The area under the receiver operating characteristic curve was 0.805±0.058 (P<0.001) for ADC. With a cut-off value of 1.317×10-3 mm2/s, ADC achieved a sensitivity of 75% and a specificity of 81.5% for the differential diagnosis of BA and non-BA. In the BA group, the ADC value was significantly correlated with fibrotic stage. Further analysis showed that the ADC value of stage F0 was significantly higher than that of stages F1, F2, F3 and F4, whereas there were no significant differences among stages F1, F2, F3 and F4.Hepatic ADC measured with DTI can be used as an adjunct to other noninvasive imaging methods in the differential diagnosis of BA and non-BA. ADC was helpful in detecting liver fibrosis but not in differentiating the fibrotic grades

Correlation of ADC or FA with fibrotic stages in the BA group (n = 32).

<p>Correlation of ADC or FA with fibrotic stages in the BA group (n = 32).</p

Comparison of ADC or FA values between the BA and non-BA groups (n = 59).

<p>Comparison of ADC or FA values between the BA and non-BA groups (n = 59).</p

Receiver operating characteristic curve of the average apparent diffusion coefficient for the detection of biliary atresia.

<p>The area under the ROC curve was 0.805±0.058 (<i>P</i><0.001) for ADC. With a cut-off value of 1.317×10⁻³ mm²/s, ADC reached a sensitivity of 75% and a specificity of 81.5% for the differential diagnosis of BA and non-BA.</p

Measurement of the apparent diffusion coefficient and fractional anisotropy on diffusion tensor imaging reconstructed images.

<p>A 165-day-old female infant with biliary atresia. Three regions of interest were drawn on each original image (b = 0), and three consecutive images (A1, B1 and C1) above the hepatic porta were included. The mean ADC values were obtained from the nine total ROIs on the ADC map (A2, B2 and C2), and the mean FA values were obtained from the FA maps (A3, B3 and C3).</p

The least significant difference (LSD) of the ADC (×10⁻³ mm²/s) between fibrotic stages in the BA group (n = 32).

<p>The least significant difference (LSD) of the ADC (×10⁻³ mm²/s) between fibrotic stages in the BA group (n = 32).</p