RESUMO
Our aim was to determine whether rotating the fetus over its largest axis and reducing the rotational step angle can improve reliability/agreement of fetal volume measurements obtained with three-dimensional ultrasonography (3-DUS). Two observers acquired three 3-DUS data sets for a fetus with a crown-rump length between 45 and 84 mm. These observers determined the fetal volume using virtual organ computer-aided analysis (VOCAL), by three different methods, with a rotational step angle of 30°: (1) minimal manipulation of the 3-DUS data set, fetus rotated over any axis; (2) manipulation of the 3-DUS data set until the fetus could be seen in a standardized manner, fetus rotated over its anteroposterior axis; (3) same 3-DUS data set manipulation, fetus rotated over its longitudinal axis. Intra- and inter-observer reliability/agreement was determined with intra-class correlation coefficients and limits of agreement. In addition, we tested the method that provided the best reliability/agreement results using 15° and 9° of rotational step angles. The time taken to manipulate 3-DUS and determine fetal volume was recorded. The best intra- and inter-observer reliability/agreement results were observed when the fetus was rotated over its longitudinal axis. Reducing rotational step angle to 15° or 9° did not further improve reliability/agreement. The observer took approximately 1 min to determine fetal volume using this method. Our findings indicate that fetal volume should be determined by rotating the fetus over its longitudinal axis, at a rotational step angle of 30°, which is relatively fast and allows analysis of fetal volume with good reliability and agreement.
Assuntos
Tamanho Corporal , Feto/anatomia & histologia , Interpretação de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Primeiro Trimestre da Gravidez , Ultrassonografia Pré-Natal/métodos , Interface Usuário-Computador , Algoritmos , Feminino , Humanos , Aumento da Imagem/métodos , Gravidez , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
PURPOSE: The objective of this study was to describe multiple Doppler ultrasound parameters of ductus venosus and inferior vena cava in fetuses at gestational ages ranging from 22 to 38 weeks. STUDY DESIGN: In this prospective observational study, Doppler ultrasound exams were performed in 45 healthy fetuses at 22, 26, 34, and 38 weeks. Maximum venous velocity, minimum venous velocity, venous pulsatility index, and venous acceleration time (VAT) (defined as the time between minimum and maximum venous velocity) were evaluated at those gestational periods. RESULTS: Increase in the velocities and decrease in the pulsatility index were observed in these vessels throughout gestational age. The VAT increased with gestational age. CONCLUSIONS: The VAT, a Doppler parameter still not described elsewhere, increased during pregnancy could be related to a longer period of time needed to fill the atrium in bigger hearts. In this study, we provide reference values for VAT in healthy fetuses.
Assuntos
Feto/irrigação sanguínea , Veia Cava Inferior/diagnóstico por imagem , Adolescente , Adulto , Feminino , Feto/fisiologia , Humanos , Gravidez , Segundo Trimestre da Gravidez , Terceiro Trimestre da Gravidez , Estudos Prospectivos , Valores de Referência , Ultrassonografia Doppler , Ultrassonografia Pré-Natal , Veia Cava Inferior/fisiologia , Adulto JovemRESUMO
OBJECTIVE(S): We intend to verify if fetal volume and crown-rump length were different between singletons and twins in pregnancies aged from 7 to 10 weeks and to evaluate if fetal volume is more accurate to determine the gestational age than crown-rump length at this gestational age. STUDY DESIGN: From 52 days (7 weeks and 3 days) to 73 days (10 weeks and 3 days) weekly three-dimensional ultrasonography was performed in 20 twin fetuses and 20 singletons. Crown-rump length and fetal volume using VOCAL were assessed in all examinations. The 'true' gestational age was based on oocyte retrieval. RESULTS: At the age of 52 days, the crown-rump length was 11.74+/-0.27 mm (mean+/-S.D.) and 11.48+/-0.22 mm (singletons and twins, respectively), while the fetal volume was 0.354+/-0.015 cm(3) and 0.324+/-0.012 cm(3). At the gestational age of 73 days, the crown-rump length was 36.19+/-0.90 mm and 35.87+/-0.54 mm and the fetal volume was 6.204+/-0.090 cm(3) and 6.083+/-0.081 cm(3). The total relative increase observed was much higher for fetal volume than for CRL: 1705+/-301% vs. 210+/-33% in singletons and 1827+/-305% vs. 214+/-25% in twins. The 95% limits of agreement (+/-2.3 days vs.+/-3.2 days, fetal volume vs. crown-rump length) and the intraclass correlation coefficients (0.989 vs. 0.978) between the "true" gestational age and that predicted by fetal volume were better than those predicted by crown-rump length. No significant difference was identified between singletons and twins for both fetal volume and crown-rump length. CONCLUSION(S): Twins and singletons had similar fetal volume and crown-rump length between the 7th and 10th week of gestational age. Additionally, fetal volume assessed by VOCAL was better than crown-rump length to estimate the gestational age at the evaluated period. However, the improvement was small and probably without clinical significance. CONDENSATION: Fetal volume and crown-rump length were similar between singletons and twins. Fetal volume relative increase was higher and the predicted gestational age was better.