Objective To investigate the influence of physiological motions on three-dimensional (3D) CT images and the rules of motion artifacts.Methods A mathematical model of motion artifact was set up based on the principle of spiral scanning, hereby the geometrical distortion of 3D image was analyzed.Experiments were carried out with home-made phantoms on a CT scanner.Results The details of 3D images with trivial distortion were legible under static condition.On the contrary, distinct distortion occured under moving condition, and its degree increased with the pitch and motion period. The 3D images were varied with difference of the motion initial phases.Conclusion The distortion of 3D-CT image depends on the motion characters of scanned objects and scanning parameters such as pitch and slice thickness.

Objective:To investigate the characteristics of renal disease spectrum in children aged 0-3 years old, and to evaluate the clinical value of renal biopsy in children aged 0-3 years old with renal diseases.Methods:It was a retrospective analysis study. The children aged 0-3 years old with kidney diseases receiving renal biopsy and having complete clinical data in Shanghai Children's Hospital from January 1, 2009 to December 31, 2020 were enrolled. The clinical and pathological data of the children were collected. The spectrum of renal diseases, clinical phenotype, renal pathology, and the relationship between renal pathology/genotype and clinical phenotype were analyzed.Results:A total of 117 children aged 0-3 years old with kidney diseases were enrolled in the study, accounting for 6.5% (117/1 790) of all children (0-18 years old) with renal biopsies during the same period. There were 77 males and 40 females. The age was (2.20±0.51) years old (5-35 months). All cases of renal biopsies in children aged 0-3 years old were successful without serious complications. Nephrotic syndrome was the common clinical phenotype of kidney diseases in children aged 0-3 years old (59.0%, 69/117), followed by hematuria and proteinuria (29.1%, 34/117). Primary glomerular disease (69.2%, 81/117) was the major clinical type of renal diseases, followed by hereditary kidney diseases (29.1%, 34/117), in which Alport syndrome was the main hereditary kidney disease (79.4%, 27/34). Renal pathological types of children aged 0-3 years old were mainly distributed in minimal change disease (30.8%, 36/117), followed by glomerular minor lesion (26.5%, 31/117), mesangial proliferative glomerulonephritis (15.4%, 18/117), and focal segmental glomerulosclerosis (10.3%, 12/117). Among 40 children aged 0-3 years old with hematuria with/without proteinuria, 25 cases were diagnosed as Alport syndrome by abnormal immunofluorescence of type IV collagen in renal tissues. Among the 28 children with kidney diseases who underwent genetic testing, 23 cases had gene mutations, mainly in COL4A5 gene (60.9%, 14/23), among which 4 children had gene mutations in 8 children with refractory nephrotic syndrome. Among the children aged 0-3 years old with clinical manifestations of hematuria, the proportion of gross hematuria in children diagnosed with Alport syndrome (59.3%, 16/27) was significantly higher than that in children without Alport syndrome (20.0%, 3/15, χ2=5.999, P=0.014). Conclusions:Primary glomerular disease is the principal type of kidney diseases in children aged 0-3 years old, followed by hereditary kidney disease. Attention should be paid to children aged 0-3 years old with gross hematuria. Renal biopsy in children aged 0-3 years old is safe and reliable, and it is an essential means for the diagnosis of renal diseases. Renal biopsy combined with gene testing can better understand the etiology of kidney diseases and guide treatment in children aged 0-3 years old.

Objective:To explore the characteristics of eye tracking movement on circumscribed interests in preschool children with autism spectrum disorder (ASD), providing some reference for behavior correction and rehabilitation training.Methods:Fifty ASD children and fifty-two age-matched typically developing children(TDC) were investigated by the childhood autism rating scale(CARS), the autism diagnostic observation schedule(ADOS), the autism diagnostic interview-revised (ADI-R) and Gesell Developmental Schedule, (GDS). Eye movement during the visual search task was captured by the Tobii Pro X3-120 eye tracker.All data were analyzed by the IBM SPSS Statistics 20.0.Eye movement patterns were compared between TDC and ASD children using the independent-sample t test, and the correlations were then analyzed between abnormal eye movement characteristics and their core syndrome. Results:The total scores of CARS, ADOS and ADI-R in ASD group were 34.13±4.59, 14.44±2.59 and 39.91±12.11 respectively.During passive viewing of complex non-social picture arrays, ASD and TDC group explored total number of images were 9.28±2.72 and 12.67±2.45.The fixation time per image explored in ASD and TDC group were (0.67±0.37)ms and (0.54±0.15)ms.Moreover, the number of discrete fixations per image explored in ASD and TDC group was 2.80±1.00 and 2.48±0.48.Compared with the TDC group, ASD children demonstrated circumscribed attention ( t=6.610, P<0.01) with more perseveration ( t=-2.363, P=0.021) and detail-orientation ( t=-2.360, P=0.021). Exploration was negatively correlated with the total score of ADOS ( r=-0.480, P<0.01), CARS ( r=-0.487, P<0.01), communication score of ADOS( r=-0.290, P=0.041), social score of ADOS( r=-0.491, P<0.01), game score of ADOS( r=-0.397, P=0.004)and communication score of ADI-R( r=-0.331, P=0.025)in the ASD group. Conclusion:Compared with TDC, the eye movement pattern shows the circumscribed interests of ASD children, who not only explore fewer objects but also demonstrate circumscribed attention with more perseveration and detail-orientation.Moreover, the more severe the symptoms of ASD children, the fewer objects the children explore and the more stereotyped the circumscribed interest.