Measurement of retropubic tissue thickness using intrapartum transperineal ultrasound to assess cephalopelvic disproportion

PURPOSE: First, to describe a new method of assessing cephalopelvic disproportion by measuring the retropubic tissue thickness (RTT), and second, to determine whether RTT was associated with an eventual delivery by cesarean section. METHODS: Three-dimensional transperineal ultrasound scans were performed on 129 laboring nulliparous women to obtain 3-dimensional volume datasets for assessing RTT. RTT was measured off-line by three operators (A, B, and C) as the shortest distance between the capsule of the pubic symphysis and the outer border of the fetal skull. The intraoperator repeatability of operator A and the interoperator reproducibility among A, B, and C were determined. The RTT in women who were delivered by cesarean section due to failure to progress was compared to that of women who had a vaginal delivery. RESULTS: The intraoperator repeatability for RTT was 1.2 mm. The overall RTT interoperator interclass correlation was 0.97 (0.95-0.98). The RTT in women who had a spontaneous, instrumental, or cesarean delivery was 1.16±0.32 cm, 1.12±0.25 cm, and 0.94±0.25 cm, respectively. Women who were delivered by cesarean section had a significantly smaller RTT than women who had a spontaneous delivery (P=0.008). There was no statistically significant difference in RTT between patients who had a normal vaginal delivery and patients who had an instrumental delivery (P=0.990), or between those who had an instrumental delivery and those who had a cesarean delivery after the Bonferroni correction (P=0.120). CONCLUSION: RTT can be measured with satisfactory intraoperator repeatability and interoperator reproducibility. RTT was significantly smaller in women who eventually had a cesarean delivery than in those who had a vaginal delivery.

Measurement of Key Elements in Rare Earth Alloy by Pulsed Glow Discharge Mass Spectrometry / 分析化学

Pulsed glow discharge mass spectrometric(Pulsed-GDMS) method for the measurement of 7 kinds of key elements(Mg,Fe,Cu,La,Ce,Pr and Nd) in rare earth alloys was established. The influence factors of measurement repeatability, such as pulse time, sample homogeneity, anode cap, flow tube, corn, and sample tablet density were systematically studied. The results showed that,for elements with mass fraction of more than mg/g, the parts (anode cap, flow tube and corn) had the largest influence on measurement repeatability. When the new graphitic parts were used and no parts were changed during the whole measurement,the relative standard deviation (RSD) was less than 3%. However, the RSD were 2%-11%and 3%-21% when the new graphitic parts and the reusable parts were used and changed,respectively. The second influence factor of measurement repeatability was the tablet density. The results showed that,the lower the density,the worse the measurement repeatability, and for the dense tablet, the RSD was less than 3%. Key elements in 1# rare earth alloy were measured by high resolution inductively coupled plasma-mass spectrometry (HR-ICP-MS), and the analytical results were used as reference values for the calibration of Pulsed-GDMS. The relative sensitivity factors (RSF) were obtained, and the key elements in 2# rare earth alloy were measured by Pulsed-GDMS after calibration. The analytical results of key elements in 2#sample by Pulsed-GDMS and HR-ICP-MS were compared, and the results showed that for the dense sample, the analytical results showed good agreement. Under the optimal conditions, the expanded uncertainty of measurement by Pulsed-GDMS reduced to 3%-10%.

Repeatability and accuracy of corneal parameters measured by RTVue Fourier-domain optical coherence topography / 中华实验眼科杂志

Background Corneal parameters (such as curvature,thickness,etc) are essential to the diagnosis of corneal related diseases,contact lenses fitting and corneal refractive surgery.Objective The aim of this study was to assess the repeatability and accuracy of corneal parameters obtained by RTVue Fourier-domain optical coherence topography (FD-OCT).Methods In this prospective study,77 eyes of 43 subjects with the refraction from-1.25 D to-10.00 D and astigmatism ＜2 D were enrolled in keratorefractive surgery center,Eye Hospital of Wenzhou Medical College.The anterior and posterior corneal curvature in 3 mm central zone (Ranterior and Rposterior),the ratio of posterior and anterior curvature (Rposterior/Ranterior),corneal central thickness (CCT),total corneal power(Knet),the simulated corneal power (Sim K),the anterior and posterior corneal power (Kanterior,Kposterior)were measured by FD-OCT.Corneal power (Km) was obtained by Topolyzer topography based on Placido ring.Three consecutive scans were acquired in every tested eye.Repeatability of FD-OCT measurement was assessed using the coefficient of variation CV),Cronbach Alpha and intra-class correlation coefficient (ICC).Repeated measure ANOVA was used to analyze the differences among SimK,Knet and Km.Pearson correlation analysis was used to analysis the correlation between SimK and K Knet and Km,SimK and Km.The agreement between Sim K and K Knet and Km,SimK and Km was assessed by Bland-Altman plots analysis.All the subjects understood the purpose of this investigation and written informed consent was obtained prior to the medical examination.Results The Ranterior,Rposterior,Rposterior/Ranterior,Kanterior,Kposterior,Sim K,Knet and CCT were (7.691 ±0.302) mm,(6.532±0.276) mm,0.849±0.014,(48.97±1.92)D,(-6.13±0.26)D,(43.95±1.72) D,(42.95±1.68) D and (545.20± 35.04) μm,respectively.The CV of all parameters was less than 1％.The Cronbach Alpha and ICC were both more than 0.9 except 0.802(ICC)of the Rposterior/Ranterior.SimK was (0.27±0.34) D higher than Km,and Knet was (0.73±0.37) D lower than Km.SimK was (1.01 ±0.11) D higher than K and all the differences showed a statistical significance (P＜0.001).There were close positive correlations between SimK and Km,Knet and Km,SimK and Knet(all r ≥ 0.976,P＜0.001).The Bland-Altman analysis showed a poor agreement between SimK and Km,Knet and Km,SimK and Knet.Conclusions The RTVue FD-OCT measuring corneal curvature and CCT performes good repeatability.The Sim K obtained by RTVue FD-OCT is slightly greater than that obtained by corneal topography,and the Rposterior/Ranterior obtained by RTVue FD-OCT is slightly lower than that from Gullstrand model eye.These results offer a basis for establishing a more accurate standardized model eye.