Conventional magnetic resonance (MR) pulse sequences typically have an echo time (TE) of 1 ms or longer, providing an excellent contrast between different soft tissues. However, some short T2 tissues appear dark in conventional MR images because the signal from these tissues has decayed to nearly zero before the center of k-space is acquired. Because of the ability of directly imaging short T2 tissues, ultrashort echo time technique has been widely studied in recent years. An overwhelming majority of the studies were carried out at high fields, while many low- field scanner systems are still used in developing countries. To investigate the effects of the delay between analog-to-digital converter sampling and the readout gradient, the TE of the second echo used to calculate the R2 * map, and the undersampling ratio on the results of three-dimensional (3D) ultrashort echo time imaging at a low field, we implemented a 3D ultrashort echo time sequence on a 0. 35T scanner. Different parameters were used and the reconstructed images and R2 * maps were compared. Images reconstructed with slightly varying delays appeared quite different. Different contrast between short and long T2 tissues were found in R2 * maps calculated with different echoes. The result of undersampling study indicated that excessive undersampling could cause unwanted blurring, making it difficult to better visualize the short T2 tissues in the R2 * map. The results suggested that cautions should be taken in the choice of these parameters in 3D ultrashort echo time imaging. Short T2 tissues can be visualized with appropriate imaging parameters at this low field.
Humans ; Image Processing, Computer-Assisted ; Imaging, Three-Dimensional ; Magnetic Resonance Imaging ; methods

Objective To assess the wall elasticity of the common carotid artery using echo-tracking in healthy children and children with hyperlipidemia.Methods The study included 68 normal healthy children and 25 children with hyperlipidemia.All the subjects were 3-18 years old.They were divided into three groups according to ages 3-6 years old group,7-13 years old group and 14-18 years old group.Echo-tracking was used to measure the pressure-strain elastic modulus (E?),stiffness parameter(?)and arterial compliance (AC) of the common carotid artery.Results The average values of E? were different among the three age groups in normal healthy children (all P

Objective To compare the effects of health education on fat intake behavior and its psychology in students with different BMI,provide evidence for improving individual healthy education.Methods A experimental epidemiology was used,Twenty-nine secondary school classes were randomly selected by multi-stage cluster sampling from two cities in Zhejiang province.Overweight or obesity group included all students who were judged overweight or obesity,normal group included students who were judged normal and basic matched by age,grade,sex and stage of baseline.Intervention based on transtheoretical mode was conducted on two groups and intervention results were measured by the adolescent fat intake behavior of psychological measurement scales (Chinese version).Chi-square tests,T-tests,non-parameters tests and binary logistic regression were performed for data analyses.Results Stage of students with overweight or obesity and with normal BMI all moved forward after intervention,while the proportion of stage advance for students with overweight or obesity was further than students with normal BMI.Change strategy(2.60±0.79),pros(3.58±0.90) and self-efficacy(3.01±0.72) of students with overweight or obesity better than students with normal BMI in baseline((2.34±0.86),(3.08±0.91),(2.79±0.81)) while difference was not significant after intervention.Logistic regression analysis discovered that the promotion of change strategy moved stage forward for students with normal BMI(OR=2.168,95％ CI:1.560-3.014)and promotion of self-efficiency moved stage forward for students with overweight or obesity (OR=1.801,95％ CI:1.026-3.159).Conclusion The intensity and duration of psychological intervention is essential to be reinforced for students with normal BMI,while for students with overweight and obesity,psychological intervention should be promoted in combination with social support.

Objectives To explore the relationships between the current physical exercise behaviors and psychological factors of middle school students,so as to provide scientific evidence for improving health education and carrying out targeted health intervention measures.Methods The Multi-stage stratified sampling and cluster sampling method was adopted to choose 3600 students from 12 junior and senior middle schools in Hangzhou,Wuhan and Xi'an.The date was collected using the adolescent physical exercise behavior-psychological measurement scale(Chinese version).The structural equation model was built to explore the relationships between psychological factors(including the change of strategy,decision balance positive effect,decision balance negative effect and self-efficiency)and physical exercise.Results The change of strategy has biggest effect on physical exercise behaviors,with the standardized direct effect value of 0.344.The standardized direct effect value of decision balance negative effect,decision balance positive effect and self-efficiency were 0.071,0.093 and 0.169 respectively.The negative correlation among the four dimensions was significant statistically.Conclusion Psychological factors have direct effects on the change of the behaviors,and the change of the strategy has the largest impact on physical exercise behaviors of middle school students.The four psychological factors are closely correlated with one another,which is important in formulating middle school sports programs to promote the physical quality of middle school students.

Objective To investigate the lens and pituitary dose impacted by additional filtration and collection field in head and neck DSA examinations. Methods All images were acquired by a Philips ALLura Xper FD 20 DSA machine. The combination of the different collection fields (48 cm, 42 cm, 31 cm, 22 cm) and additional filtrations (0.9 mmCu+1.0 mmAl, 0.4 mmCu+1.0 mmAl, 0.1 mmCu+1.0 mmAl) were adjusted when the anthropomorphic phantom filled with dosimeter was scanned in anterioposterior and lateral positions with 2D?DSA and 3D?DSA. The dose area product (DAP), air kerma (AK) and the radiation dose values of bilateral lens and pituitary were measured and recorded. The 2D and 3D?DSA regional absorption dose on lens and pituitary were analyzed using t' test, the correlations between DAP and AK parameters and different regional absorption doses were evaluated by Pearson rank correlation coefficient. Results Absorption doses of left lens, right lens and pituitary with 2D?DSA (n=12) were as following:(2.77 ± 0.68), (6.23 ± 3.54), (8.65 ± 2.62) mGy, while the parameters with 3D?DSA (n=12) were (1.78 ± 0.82), (2.18±1.15), (3.32±0.64) mGy, respectively;the results revealed a significant difference (t'=3.20, 3.76 and 6.85, P<0.01). DAP [(8 739±5 731) mGy·cm2] had a relationship with absorption dose of pituitary, left lens and right lens [(5.988 ± 3.299),( 2.258 ± 0.872),( 4.207 ± 3.303) mGy, r values were 0.766, 0.684, 0.727; P<0.01]. AK values was (31 ± 23) mGy and it had a relationship with pituitary absorption dose (r value was 0.894, P<0.01). The lens dose was reduced when the additional filtration was increased and the collection field was decreased, the radiation dose of the pituitary was reduced when both the additional filtration and the collection field were increased. Conclusions In the head and neck DSA examinations, the radiation dose of the lens and the pituitary had different changes with the different additional filters and collecting fields. The organ dose with 3D?DSA was significantly less than that with 2D?DSA.

Objective To compare the therapeutic effect of Midodrine hydrochloride plus oral rehydration salts,Metoprolol plus oral rehydration salts and simple oral rehydration salts on children with postural tachycardia syn-drome(POTS). Methods One hundred and ninety - two children with POTS were divided into Midodrine hydrochlo-ride plus oral rehydration salts group(84 cases),Metoprolol plus oral rehydration salts group(54 cases)and oral rehy-dration salts group(54 cases). The patients were followed up at the outpatient department after 3 - months treatment. Short - term effect was analyzed by reevaluating the symptom scores,repeating upright test and studying the side effects of the drugs. All the children were followed - up by telephone,mainly investigating on the syndrome recurrence and symptom - free survival by Kaplan - Meier analysis. The follow - up time was 3 to 122(42. 7 ± 24. 3)months. Results Short - term effect showed that the symptom scores were decreased after treatment(t = 21. 536,P ﹤ 0. 001). Head -up test showed that delta heart rate was decreased. The effective rates in the Midodrine hydrochloride plus oral rehydra-tion salts group and the Metoprolol plus oral rehydration salts group were significantly higher than those of the simple oral rehydration salts group(χ2 = 10. 905,P = 0. 004). But no statistical difference was found between the Midodrine hydrochloride plus oral rehydration salts group and the Metoprolol plus oral rehydration salts group(χ2 = 0. 042,P =0. 837). Long - term effect by Kaplan - Meier curve showed that the therapeutic effect of Midodrine hydrochloride plus oral rehydration salts group was significantly higher than any of the other two groups(χ2 = 13. 299,P ﹤ 0. 01),but no statistical difference was found between the Metoprolol plus oral rehydration salts group and the simple oral rehydration salts group(χ2 = 0. 150,P = 0. 699). Conclusions In terms of the short - term result,the effective rates in the Mido-drine hydrochloride plus oral rehydration salts group and the Metoprolol plus oral rehydration salts group were signifi-cantly higher than those of the simple oral rehydration salts group. The therapeutic effect of the Midodrine hydrochloride plus oral rehydration salts was superior to that of the Metoprolol plus oral rehydration salts and the simple oral rehydra-tion salts for POTS children by the long - term follow - up study.

Objective: To explore the relationship between venous blood routine test parameters and syncopal recurrence of children with vasovagal syncope (VVS). Method: Sixty-three children (male 32, female 31) diagnosed as VVS in Department of Pediatrics, Peking University First Hospital from November 2010 to October 2015 were included in a case observational study.Their mean age was (11.2±2.7) years and basic treatment such as predisposing causes avoiding, standing training, autonomic nervous function exercise and oral rehydration salts were advised to them.The clinical data were obtained by out-patient visit and over telephone from December 2015 to January 2016, with a median follow-up period of 10 (4, 26) months. The effects of baseline venous blood routine test parameters, gender, age, and body mass index (BMI) on syncopal recurrence were studied via univariate and multivariate Cox regression analysis.Kaplan-Meier curve was used to evaluate the long-term prognosis. Result: Among the 63 VVS children in this study, 31 cases were diagnosed as VVS vasodepressor type, 4 cases as VVS cardioinhibitory type and 28 cases as VVS mixed type, 16 cases (25%) had experienced recurrence of syncope while 47 cases (75%) had not.The result of univariate analysis of Cox regression showed that baseline platelet count (PLT) (HR=1.012, 95%CI: 1.003-1.022) had a marked impact on the survival rate.And the result of multivariate analysis of Cox regression showed that baseline hemoglobin concentration (HGB) (HR=1.055, 95%CI: 1.007-1.105), mean corpuscular hemoglobin (MCH) (HR=0.612, 95%CI: 0.423-0.884) and PLT(HR=1.015, 95%CI: 1.006-1.024) had significant effects on survival rate of VVS children.In this study, the one-year, two-year, and three-year survival rate were 83% (52/63), 79% (50/63) and 75% (47/63), respectively. Conclusion The baseline venous blood routine test parameters HGB, MCH and PLT might be the influencing factors of the syncopal recurrence of VVS children.

OBJECTIVETo explore possible mechanisms of postural tachycardia syndrome (POTS) by comparing plasma intermedin (IMD) during head-up tilt test (HUTT) in children with POTS.

METHODThe study subjects were divided into two groups: POTS group and control group. The POTS group consisted of twenty-nine children (male 14, female 15) with POTS, the mean age (12.4 ±3.1) years old, admitted into Peking University First Hospital from November 2013 to June 2014. The control group consisted of 32 healthy children (male 17, female 15). Their mean age was (11.6±2.2) years old, who were confirmed as healthy by physical examination and HUTT. Finapres Medical System was used to continuously monitor heart rate and blood pressure during HUTT, and electrocadiogram was performed. Supine systolic and diastolic blood pressure, mean arterial pressure (MAP), ΔMAP (standing mean arterial pressure-supine MAP), supine heart rate and ΔHR (standing HR-supine HR) were compared between POTS group and control group. Sandwich immunoluminescence assay was used to test plasma IMD. The plasma IMD level was compared in supine between POTS and control group. The plasma IMD level in supine was compared with HUTT in POTS group.

RESULTNo significant differences were found in age, height, weight, supine systolic and diastolic blood pressure, MAP, ΔMAP and supine heart rate between POTS group and control group (P>0.05). ΔHR in POTS group was significantly higher than that of control group ((48±10) vs. (22±7) beats /min, t=9.797, P<0.05). The plasma IMD level in POTS group was lower than that of control group in supine position ((497±61)×10(-6) vs. (529±58)×10(-6) mg/L, t=2.117, P<0.05). But, it was higher during HUTT than supine IMD in POTS group ((537±57) ×10(-6) vs. (497±61)×10(-6) mg/L, t=-2.464, P<0.05). The plasma delta IMD level (HUTT vs. supine) was positively correlated with delta HR in POTS group (r=0.435, P<0.05).

CONCLUSIONThe excessively high heart rate during HUTT have a positive correlation with plasma IMD, which may play a role in the pathogenesis of POTS in children.

OBJECTIVETo predict the therapeutic efficacy of oral rehydration salts (ORS) by quantifying changes in heart rate during the head-up test (HUT) in children with postural tachycardia syndrome (POTS).

METHODFifty-four children from Peking University First Hospital during July 2005 to September 2013 were enrolled into POTS group. Twenty healthy children were enrolled in this study as the control group. Children with POTS were treated with ORS and successfully followed up. HUT test was done before and at the end of the treatment. POTS children were further divided into responding group and the non-responding group depending on if the symptom scores were reduced by 50% or greater after the treatment. The heart rate, systolic blood pressure (SBP) and diastolic blood pressure (DBP) changes during the HUT test were analyzed between the control group and the POTS patients. A receiver operating characteristic (ROC) curve was used to analyze the predictive value of the increase in heart rates (from the supine to upright) and the maximum upright heart rate in 10 minutes after ORS treatment.

RESULTPOTS children were 6-17 (11.3 ± 3.0) years old and the control group children were 10-12 (11.0 ± 0.8) years old. The changes of the heart rate during the HUT was different between the POTS patients and the controls ((41 ± 10) vs. (20 ± 7) beats/min, t = -10.441, P = 0.000) . There was no significant difference between the two groups in the maximum upright heart rate in 10 minutes during the HUT ( (117 ± 12) vs. (114 ± 8) beats/min, t = -1.322, P = 0.192) . The symptom scores were reduced compared with those before treatment ((3.2 ± 1.8) vs. (5.7 ± 2.0), t = 10.958, P < 0.001) and the heart rate changes from supine to upright were decreased in 30 patients ((33 ± 11) vs. (41 ± 11) beats/min, t = 2.956, P = 0.006). Compared with the non-responding group (28 cases), the heart rate change during the HUT test was great in the responding group (26 cases) before treatment ((46 ± 10) vs. (37 ± 9) beats/min, t = -3.582, P = 0.001), and the maximum upright heart rate in 10 minutes was also high in the responding group ( (122 ± 12) vs. (113 ± 10) beats/min, t = -2.693, P = 0.010). The ROC curve showed that ORS for children with POTS would be predicted to be effective when the pre-treatment increase of heart rate was 41 beats/min (sensitivity 72% and specificity 70%), or when the maximum upright heart rate in 10 minutes was 123 beats/min before treatment (sensitivity 48% specificity 56%). When the two indices were used together, sensitivity was 84% and specificity was 56%.

CONCLUSIONThe changes in heart rate during the HUT was useful in predicting the response to ORS in children with POTS.

Blood Pressure ; Child ; Fluid Therapy ; Heart Rate ; Humans ; Postural Orthostatic Tachycardia Syndrome ; physiopathology ; therapy ; Predictive Value of Tests ; ROC Curve ; Salts ; Sensitivity and Specificity ; Treatment Outcome

OBJECTIVETo explore the predictive value of baseline plasma midregional fragment of pro-adrenomedullin level (MR-proADM) on long-term survival of postural tachycardia syndrome (POTS) children treated with midodrine hydrochloride.

METHODSFifty-three children (male 26, mean age (14.5 ± 4.5) years old) with POTS were included in this study, and all of them were diagnosed as POTS in our department from December 2007 to January 2010. Fifty-three children with POTS were divided into two groups according to the baseline plasma content of MR-proADM. Group I consisted of 35 POTS children with plasma content of MR-proADM > 61.5 ng/L, and the group II consisted of 18 POTS children with plasma content of MR-proADM ≤ 61.5 ng/L. The mean follow-up time was (67 ± 7) months. The orthostatic intolerance symptom score and the symptom free survival were compared between the 2 groups.

RESULTSAt the 60 months follow-up, the symptom score of children in group I was significantly lower than that in group II (χ(2) = 4.985, P < 0.05). At 72 months follow up, the symptom score was similar between the 2 groups (χ(2) = 0.004, P > 0.05) while the symptom free survival of group I was significantly higher than that in group II (χ(2) = 4.566, P < 0.05).

CONCLUSIONThe baseline plasma MR-proADM level is value in predicting the long-term survival of POTS children treated with midodrine hydrochloride.

Adolescent ; Adrenomedullin ; Child ; Humans ; Male ; Midodrine ; therapeutic use ; Postural Orthostatic Tachycardia Syndrome ; diagnosis ; drug therapy ; ROC Curve ; Vasoconstrictor Agents ; therapeutic use