nal abnormalities of pediatric heart diseases.

Objective To study the application CT scans in Nuss procedure for pectus excavatum. Metlhods 648 children with pectus excavatum underwent Nuss procedure from July 2002 to September 2008 The preoperative CT scan was carried out for evaluation of the deformity degree and morphology classification of chest wall malformation, the deformity in relation with adjacent tissue and associated different disorder. Results Nuss procedure was successfully performed in all 648 patients. The preoperative CT scan showed medium deformity of the pectus excavatum in 73 cases ( 11.27% ) and severe deformity in 575 cases (88.73%). Morphologic classification of the pectus excavatum were symmetric type in 407cases (62.81% ) , eccentric type in 83( 12.81% ) ,and unbalanced type in 158( 24.38% ). 116 cases with pectus excavatum were associated with other different disorders, among them 55 cases ( 17.9% )were diagnosed by CT scan. 28 cases received stimultanously operation for their abnormalities. Conclusion CT scan is a useful tool for evaluation the deformity degree and morphology classification, direct the operation, reduce the complications and find other different disorders. It should be a routine examination before Nuss procedure.

Objective To investigate the feasibility to reduce radiation doses on pediatric mutidetector abdominal CT using the adaptive statistical iterative reconstruction technique (ASIR) associated with automated tube current modulation technique(ATCM).Methods Thirty patients underwent abdominal CT with ATCM and the follow-up scan with ATCM cooperated with 40％ ASIR.ATCM was used with agedependent noise index (NI) settings: NI =9 for 0-5 year old and NI =11 for ＞ 5 years old for simple ATCM group,NI =11 for 0-5 year old and NI =15 for ＞5 years old for ATCM cooperated with 40％ ASIR group(AISR group).Two radiologists independently evaluated images for diagnostic quality and image noise with subjectively image quality score and image noise score using a 5-point scale.Interobserver agreement was assessed by Kappa test.The volume CT dose indexes (CTDIvol) for the two groups were recorded.Statistical significance for the CTDIvol value was analyzed by pair-sample t test.Results The average CTDIvol for the ASIR group was (1.38 ± 0.64) mGy,about 60％ lower than (3.56 ± 1.23) mGy for the simple ATCM group,and the CTDIvol of two groups had statistically significant differences.(t =33.483,P ＜ 0.05).The subjective image quality scores for the simple ATCM group were 4.43 ± 0.57 and 4.37 ±0.61,Kappa =0.878,P ＜ 0.01 (ASIR group: 4.70 ± 0.47 and 4.60 ± 0.50,Kappa =0.783,P ＜ 0.01),by two observers.The image noise score for the simple ATCM group were 4.03 ±0.56 and 3.83 ±0.53,Kappa =0.572,P ＜ 0.01 (ASIR group: 4.20 ± 0.48 and 4.10 ± 0.48,Kappa =0.748,P ＜ 0.01),by two observers.All images had acceptable diagnostic image quality.Conclusion Lower radiation dose can be achieved by elevating NI with ASIR in pediatric CT abdominal studies,while maintaining diagnostically acceptable images.

Objective To explore the mechanism of the role of mitomycin C(MMC)in regulating miR-200b expression and inducing fibroblasts apoptosis. Methods Fibroblasts cultured in vitro were treated with different concentrations of MMC for 5 min and continue culture for 24 h. The expression of miR-200b were analyzed by Real-time PCR. Cell apoptosis were observed using TUNEL staining. The expression of cleaved-PARP,Bax and Bcl-2 were detected by Western blot. The methylation level of miR-200b promoter were measured by BSP. Results After treated with MMC,The expression of miR-200b significantly downregulated.TUNEL Staining analysis demonstrated MMC could significantly induce human fibroblasts apoptosis. Western blot results showed cleaved-PARP,Bax increased and Bcl-2 decreased.The methylation ratio of miR-200b promotor increased and has a significant dose dependent. Conclusion MMC induced human fibroblasts apoptosis by promoting miR-200b promoter methylation.

Objective To compare the curative effect and biomechanical performance of cannulated compression screw (CCS) and dynamic hip screw-blade (DHS-B) in the treatment of patients with femoral neck fracture.Methods Between February 2010 and February 2014,102 patients with femoral neck fracture were treated with CCS or DHS-B at our department.They were 54 males and 48 females,aged from 15 to 86 years.There were 30 subcapital fractures,51 transcervical ones and 21 base ones.CCS was used in 60 patients and DHS-B in 42.In-hospital data were collected retrospectively to compare the curative effects in 2 groups.Furthermore,femoral neck fracture models were established using 12 adult cadaveric femoral specimens.The 12 models were randomized into 2 equal groups (n =6).Group A was subjected to fixation by 3 CCSs and group B to fixation by DHS-B.The 2 groups were compared in terms of axial loading test,rotation test and destructive axial loading test.Results The operation time (59.4 ± 20.2 min),incision size (4.1 ±0.6 cm) and intraoperative blood loss (25.9 ±9.9 mL) in the CCS group were significantly less than those in the DHS-B group (88.6±22.9 min,12.1 ±1.2cmand 156.7±107.1 mL) (P ＜0.05).The Harris hip score for the DHS-B group (91.9±9.8) was significantly higher than that for the CCS group (87.2 ± 9.2) (P ＜ 0.05).There were no significant differences between the 2 groups in hospital stay,partial weight-bearing time,or postoperative complications (P ＞ 0.05).At 500 N vertical loading,the stress values at both medial and lateral sides of the femur in group A were significantly smaller than those in group B (P ＜ 0.05).There were no significant differences between groups A and B in the average sinking displacement of femoral head or the torque at a torsion angle of 6° (P ＞ 0.05).The maximum load in group A (2,135 ±120 N) was significantly smaller than that in group B (2,986 ± 98 N) (P ＜ 0.05).Conclusion In treatment of femoral neck fracture,DHS-B fixation is obviously superior to CCS fixation,because the former is in better agreement with the femoral biomechanical property,and performs better in anti-rotation and anti-compression,leading to better functional recovery of the affected hip.

Objective To access the development of thoracic volume of pectus excavatum use of Nuss operation used CT-basedpulmonary volumetric evaluation.Methods 98 patients with pectus excavatum in Beijing Children's Hospital under Nuss operation were documented.All patients had CT scan pre-and postopration.The CT-scan's data were calculated as lung's volume by handdraw-layers summation method.The lung's volume result was compared,and enquiry the position in CT lung volume developmental scale.Results The lung's volume was elevated 28.3％ after operation.The development of thoracic volume was keep with age,70％ was maintained and 15％ was elevated.Conclusion Nuss operation can prevent the decrease of thoracic volume in pectus excavatum.

Objective To evaluate the feasibility of model-based iterative reconstruction (MBIR) in low-dose chest CT (80 kV) examination in children.Methods Forty-four children who had post-operation scoliosis and received low dose chest CT scans were included.The fix tube voltage was 80 kV,fix current was 50 mA.Images were reconstructed with MBIR (observation group).The pre-operation scan were used 120 kV and 50 mA for acquisition,and images were reconstructed with filtered back-projection (FBP) mehed (control group).The subjective quality of the images was independently evaluated by two radiologists.Objective noises in the muscle and lung field were measured,the SNR,CNR were calculated,and the CTDIvol was record.Results The subjective noise score in the observation group was significantly higher than that in the control group (P＜0.05).Objective noise reduced about 40.36％,SNR increased 72.37％,CNR increased 78.69％,CTDIvol decreased by 66.52％,all of which had statistical difference between both groups (all P＜0.001).Conclusion Low-dose chest CT (80 kV) examination in children can meet the requirements of diagnosis for children.

Objective To explore the value of adaptive statistical iterative reconstruction (ASIR) and a sharp recon kernel to obtain high resolution pulmonary images in low-dose pediatric chest CT scans.Methods Totally 42 children underwent low-dose chest CT scans with ASIR were included.Age dependent noise index (NI) was used for dose optimization:NI=12 for 0-12 months old,NI=15 for ＞1 2 years old,NI=17 for 3-6 years old and NI=20 for ≥7 years old.Images were reconstructed to 0.625 mm using different recon kernels:Soft,Standard,Lung,and Chest kernel.ASIR blending was varied from 0 100％ to provide balanced image noise and spatial resolution.Two radiologists independently evaluated images for normal lung structures,abnormal CT findings and image noise on a 5 point scale with 3 being clinically acceptable.The best kernel,as well as the match with the best ASIR weight were analyzed statistically.Results CT images with lung kernel and ASIR 60％ were rated substantially better than those kernel.Conclusion ASIR 60％ with a sharp lung kernel can significantly improve image quality in low dose pediatric chest CT scans.

BACKGROUND:The pathogenesis of knee intraarticular adhesion is yet unknown. Excessive proliferation of fibroblasts is considered to cause knee intraarticular adhesion. OBJECTIVE:To study the preventive effects of methotrexate on knee intraarticular adhesion through fibroblast apoptosis induced by endoplasmic reticulum stress. METHODS:The viability of the cultured fibroblasts treated with methotrexate(10-5-10-9mol/L)or PBSwas determined after 24 hours. Fibroblast apoptosis was detected by Hoechst33342 staining. Endoplasmic reticulum stress-and apoptosis-related proteins, including cleaved-PARP, CHOP, Bax and Bcl-2, were determined by western blotassay. Eighteen healthy male New Zealand white rabbits were used to establish the knee intraarticular adhesion models, and equaly randomized into three groups, and received topical application of 2 or 1 g/L methotrexate, or normal saline (control). The preventive effects of methotrexate on knee intraarticular adhesion and CHOP expression in scar tissue were observed. RESULTS AND CONCLUSION:Methotrexate inhibited the proliferation and viability of fibroblasts in a dose-dependent manner. The number of apoptotic fibroblasts was significantly increased compared with control group. Protein expression of cleaved-PARP, CHOP, and bax was increased, while protein expression of bcl-2 was decreased with time. The animal experiment showed that preventive effects of 2 g/L methotrexate on knee intraarticular adhesion were superior to 1 g/L methotrexate treatment. CHOP expression in the scar tissue in the methotrexate groups was higher than the control group and that was higher in high-dose methotrexate group. Our results suggest that methotrexate prevents knee intraarticular adhesionviaendoplasmic reticulum stress-induced fibroblast apoptosis.

Objective:To investigate the clinical efficacy of TiRobot-assisted minimally invasive percutaneous screw fixation for pelvic fractures.Methods:The clinical data of 44 patients with pelvic fracture were retrospectively analyzed who had undergone TiRobot-assisted minimally invasive percutaneous screw fixation from May 2018 to April 2021 at Department of Orthopedic Traumatology, The First Hospital of Jilin University. There were 30 males and 14 females, aged from 11 to 78 years (average, 40.6 years). According to the Tile classification, there were 20 type C1 fractures, 23 type C2 fractures and one type C3 fracture. The time from injury to operation averaged 8.2 days (from 1 to 41 days). The minimally invasive percutaneous screw fixation was assisted by the orthopaedic TiRobot in all patients. Operation time, fluoroscopy time, reduction quality, complications and functional recovery at the final follow-up were recorded and analyzed.Results:A total of 96 screws were implanted in this cohort. The total fluoroscopy time ranged from 17 to 66 s, with an average of 17.8 s for each single screw. The operation time ranged from 50 to 355 min, averaging 179.7 min. According to the Matta criteria, the reduction quality was rated as excellent in 36 cases, as good in 5 and as fair in 3, yielding an excellent and good rate of 93.2%(41/44). All the 44 patients were followed up for 6 to 42 months (average, 20.4 months). The fracture healing time ranged from 2 to 6 months, averaging 3.3 months. The Majeed scores at the final follow-up ranged from 51 to 100 points (average, 83.7 points); there were 28 excellent, 8 good, 7 fair and one poor cases, giving an excellent to good rate of 81.8% (36/44). Follow-up found no such complications as iatrogenic neurovascular injury, incision infection, malunion, implant loosening or fracture re-displacement in all the 44 patients.Conclusion:TiRobot-assisted minimally invasive internal fixation can result in fine clinical efficacy for pelvic fractures, showing advantages of accuracy, minimal invasion and safety.