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Based on the reason that the growth of discrete grey model is constant, the paper structured quadratic time-varying parameters discrete grey model (referred to as QDGM(1,1)) by introducing quadratic time-varying terms. And then the paper researched properties of the new model, and reached the conclusion that QDGM(1,1) possessed white exponential law coincidence, linear law coincidence, quadratic law coincidence and consistency of stretching transformation. What's more, the paper applied optimization method to optimizing the iterative starting value of the new model, and introduced the steps of using QDGM(1,1) to predict. Finally, the new model was compared with another three discrete grey models through an instance. It was proved that the new model greatly improves the simulation and prediction precision. [ABSTRACT FROM AUTHOR]

Background: Double aortic arch is the most common form of complete vascular ring. The trachea and/or esophagus could be compressed by the complete vascular ring, which may lead to early respiratory and/or esophageal symptoms in children with double aortic arch. Accurate prenatal assessment of tracheal compression could provide relevant information for perinatal clinical management of double aortic arch and emergency treatment of infants with double aortic arch. The fetal trachea is filled with amniotic fluid and can be clearly visualized with prenatal ultrasound. Previous studies reported the use of prenatal ultrasound to measure the tracheal internal diameters in normal fetuses and showed a linear correlation between the fetal tracheal internal diameters and gestational age. However, to the best of our knowledge, few studies have quantitatively evaluated tracheal compression in fetuses with double aortic arch using ultrasound., Objective: This study aimed to evaluate the tracheal compression caused by the vascular ring in fetuses with double aortic arch using prenatal ultrasound and to analyze the relationship between tracheal compression and postnatal clinical symptoms., Study Design: The data of fetuses with double aortic arch diagnosed with prenatal ultrasound at 2 institutions from January 2011 to April 2021 were retrospectively analyzed. Singleton pregnancies with normal fetuses as the control group were prospectively recruited. The tracheal compression-evaluated by comparing the tracheal internal diameter z scores against the gestational age-was assessed in fetuses with double aortic arch and in normal fetuses. The live-born infants with double aortic arch were divided into symptomatic and asymptomatic groups for the comparison of z scores. The receiver operating characteristic curve for the tracheal internal diameter z score cutoffs and prediction of symptomatic infants with double aortic arch was plotted. Intraobserver and interobserver agreements were investigated., Results: A total of 26 fetuses with double aortic arch were diagnosed, and 14 fetuses (53.8%) with double aortic arch were delivered alive. Among the 14 live-born infants, 7 (50.0%) were symptomatic, whereas 7 (50.0%) were asymptomatic. The tracheal internal diameter z scores were significantly lower in the double aortic arch group than in the normal groups (-0.62±1.36 vs 0.00±0.78; P<.001). The tracheal internal diameter z scores were significantly lower in the symptomatic group than in the asymptomatic group (-1.42±0.92 vs -0.49±0.96; P=.018). The area under the curve was 0.878 (95% confidence interval, 0.689-1.000). Using a tracheal internal diameter z scores cutoff of -1.21, the sensitivity was 71%, and the specificity was close to 100%. The intraclass correlation coefficients of interobserver and intraobserver agreements were 0.987 (95% confidence interval, 0.980-0.992) and 0.975 (95% confidence interval, 0.955-0.987), respectively., Conclusion: The clinical symptoms in infants with double aortic arch were associated with prenatal tracheal compression, which can be prenatally evaluated using ultrasound. If fetuses are diagnosed with double aortic arch, prenatal surveillance of the tracheal internal diameters and comparison with z score reference ranges could provide pertinent information that would aid perinatal clinical management., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)