Nasal-bone length in euploid fetuses at 16-24 weeks' gestation by three-dimensional ultrasound.

OBJECTIVE: To establish a normal range of nasal-bone length at 16-24 weeks' gestation by the use of three-dimensional (3D) ultrasound and to investigate the effect of deviations from the exact mid-sagittal plane on the measurement of nasal-bone length. METHODS: We acquired 3D volumes of the fetal profile from 135 normal fetuses at 16-24 weeks' gestation. The multiplanar mode was used to obtain the exact mid-sagittal plane and to produce parasagittal and oblique views of the fetal face. Nasal-bone length was measured in each plane and the sonographic landmarks of each profile view were examined. RESULTS: Nasal-bone length increased with gestational age from a mean of 4.1 mm at 16 weeks to 7.1 mm at 24 weeks. There was a tendency to underestimate nasal-bone length when the measurements were taken in parasagittal planes and to overestimate the measurements when they were taken in oblique views, compared to the exact mid-sagittal plane. The mean difference in nasal-bone length from the one in the mid-sagittal plane was 0.42 and 0.63 mm for parasagittal measurements at 1 and 2 mm, respectively, from the midline, -0.08 and -0.51 mm for oblique measurements at 10 degrees and 20 degrees rotation along the z-axis and -0.69 mm for rotation of 20 degrees along the z-axis and 10 degrees along the y-axis. The vomeral bone was the only sonographic landmark defining the exact mid-sagittal plane of the face that was not visible in the parasagittal and oblique planes. CONCLUSIONS: Parasagittal and oblique scanning planes may produce different degrees of under- or over-estimation of nasal-bone length compared to measurements systematically taken in the exact mid-sagittal plane. Inclusion of the vomeral bone in the definition of the exact mid-sagittal plane of the face could improve the reproducibility of measurements of nasal-bone length.

Depth of brain fissures in normal fetuses by prenatal ultrasound between 19 and 30 weeks of gestation.

OBJECTIVE: To establish normal reference ranges for the depth of the insula and Sylvian (SF), parieto-occipital (POF) and calcarine (CF) fissures on prenatal ultrasound between 19 and 30 weeks of gestation. METHODS: This was a prospective study of 15 consecutive normal fetuses per gestational week between 19 + 0 and 30 + 6 weeks. We measured the depth of the insula and SF in a standard transventricular axial plane of the fetal head; the depth of the POF in a plane above and parallel to that used for the insula; and the depth of the CF in a coronal view of the posterior fossa. All measurements were done transabdominally during the routine second- or third-trimester examination. Reproducibility for each of the parameters was assessed by two operators using stored images from 30 cases. RESULTS: The depth of the four structures increased with increasing gestational age. The insula and SF could be seen in all cases from 19 weeks onwards, while the POF and CF could be identified in 93.3% and 6.6% of cases, respectively, at 19 weeks. From 20 weeks onwards, the POF could be seen in all examinations, as could the CF from 24 weeks. Intra- and interobserver reproducibility analysis showed good results. CONCLUSIONS: Assessment of the insula, SF, POF and CF is feasible during prenatal ultrasound examination using standard views of the fetal head. Since the normal ranges increase with gestational age, they could be used to estimate brain development. It is possible that this assessment might be incorporated into the neurosonogram to identify fetuses at risk of maturation disorders or as a complement to other standard evaluations.

Marcadores ecográficos para la detección del síndrome de Down en las semanas 11-13 + 6 / Sonographic markers for Down´s Syndrome screening at 11-13 + 6 weeks

Objetivo. Presentar nuestra experiencia en la valoraciónde todos los marcadores ecográficos validados para el cribadodel síndrome de Down en la semana 11-13 + 6.Métodos. Capacitamos seis médicos para evaluar elhueso nasal (HN), flujo tricuspídeo (FT) y flujo en el ductusvenoso (DV) durante una exploración de 20 min en las semanas11-13 + 6. Comparamos los resultados con los obtenidospor el médico capacitador, en dos mitades. En un subgrupode tres médicos valoramos además la realización delángulo facial. Utilizamos como guía los parámetros de la FetalMedicine Foundation, Londres.Resultados. El número total de exploraciones fue de939. El grupo de seis médicos realizó 356 exploraciones enla primera mitad, y 355 en la segunda mitad; las valoracionessatisfactorias fueron para traslucencia nucal (TN) 85,4 y89 %, HN 82,7 y 82,7 %, FT 82,7 y 86,8 %, DV 89 y 86,6%respectivamente. El capacitador obtuvo en 228 exploracionesresultados satisfactorios en 100% TN, 94,7 % HN,99,6 % FT, 97,3 % DV y 73,5 % ángulo facial (AF). El AF fuevalorado satisfactoriamente por el subgrupo de tres médicosen el 69 % de los casos.Conclusiones. Es posible valorar todos los marcadoresecográficos de aneuploidía en la mayoría de los casos en semanaslas 11-13 + 6. La TN fue el marcador con resultadosmás satisfactorios. El entrenamiento continuo y la auditoriason indispensables para mejorar el estándar del cribado parael síndrome de Down en las semanas 11-13 + 6 (AU)

Objective. To report our experience in the assessmentof all the available ultrasound markers for Down´sSyndrome screening at 11-13 + 6 weeks of gestation.Methods. We trained six doctors to evaluate the nasalbone (NB), tricuspid regurgitation (TR), and a-wave inthe ductus venosus (DV), during a routine 20 minutescan. We compared the results in two halves, with thoseobtained by the trainer. In a subgroup of three doctors,we assessed the facial angle (FA) with the same methodology.The audit of the stored images was performed bya doctor with experience in first trimester markers. Wefollowed guidelines from the Fetal Medicine Foundation,London for the assessment of the markers.Results. We examined 939 patients. The group of sixdoctors performed 356 and 355 scans in each half of thestudy respectively. The assessment was satisfactory foreach marker: nuchal translucency thickness (NT) 85.4%and 89%, NB 82.7% and 82.7%, TR 82.7% and 86.8%,DV 89% and 86.6% respectively. The trainer performed228 scans and the results were satisfactory in 100% TN,94.7% NB, 99.6% TR, 97.3% DV and 73.5% facial angle.In the subgroup with 3 doctors, the facial angle was satisfactorymeasured in 69% of the cases.Conclusions. It is feasible to assess all the ultrasoundmarkers for chromosomal abnormality in a 20 minutescan in a high proportion of cases. NT assessmentwas the most successful. The continuous training andaudit process are critically important to rise the standardof the 11-13 + 6 weeks Down’s Syndrome screening (AU)

Prenasal thickness in trisomy-21 fetuses at 16-24 weeks of gestation.

OBJECTIVE: To construct a reference range for fetal prenasal thickness between 16 and 24 weeks of gestation and to evaluate the thickness in fetuses with trisomy 21. METHODS: We acquired three-dimensional (3D) volumes of the fetal profile from 135 normal fetuses and 26 fetuses with trisomy 21 at 16-24 weeks' gestation. We used the multiplanar mode to obtain the exact mid-sagittal plane and measured the prenasal thickness as the shortest distance between the anterior edge of the lowest part of the frontal bone (at the junction with the nasal bone when present) and the skin anteriorly. RESULTS: In the normal group prenasal thickness increased with gestation from a mean of 2.4 mm at 16 weeks to 4.6 mm at 24 weeks. Repeatability studies demonstrated that in 95% of the cases the difference between two measurements of prenasal thickness by the same operator and by different operators was less than 1 mm. In the trisomy-21 fetuses the mean prenasal thickness was significantly larger than in normal fetuses and in 19 (73.1%) cases it was above the 95(th) centile of the normal range. There was no significant difference in prenasal thickness between the trisomic fetuses with and without ventriculomegaly, nuchal edema, absent nasal bone or a cardiac defect. CONCLUSIONS: The fetal profile is routinely examined during the second-trimester scan and therefore the skill needed to obtain the view necessary for the measurement of prenasal thickness is widely available. If the finding of our study--that in more than 70% of fetuses with trisomy 21 prenasal thickness is above the 95(th) centile--is confirmed in prospective screening studies this measurement alone could prove a highly sensitive method of second-trimester screening for trisomy 21.

Ecografía obstétrica tridimensional y 4D: factores condicionantes de la imagen y curva de aprendizaje / Three and four-dimensional ultrasound: when and how to obtain the best images? The 3D learning curve

Objetivos. Analizar los factores condicionantes en laobtención de imágenes en ecografía obstétrica 3/4D, enparticular la edad gestacional, la experiencia del ecografista, las condiciones fetales y el índice de masa corporal. Analizar la curva de aprendizaje en ecografía obstétrica 3/4D para expertos en ecografía 2D convencional. Material y métodos. Se incluye un total de 1.017 ecografías obstétricas en gestaciones únicas, seleccionadas de forma aleatoria, excluyéndose la sospecha o evidencia de malformación fetal. El estudio ha sido realizado en un centro privado, entre agosto del 2005 y marzo del 2006, con un Voluson 730 Expert (GE Medical System), con la participación de nueve expertos en ecografía obstétrica 2D. La experiencia en ecografía 3/4D se ha clasificado en nivel I (sin experienciaprevia en esta técnica), nivel II (experiencia entre6 y 12 meses) y nivel IIII (experiencia superior a 1 año). Se efectúa una ecografía 2D detallada y sistemática de la anatomía fetal, seguida de la obtención de imágenes 3/4D de las partes fetales más reconocibles del feto, mediante el modo de renderización de superficie, con una duración máxima de la exploración de 25-30 min. Después del examen ecográfico se rellenan tres cuestionarios dirigidos a la paciente, al médico ecografista y a un observador independiente no médico. Analizamos el impacto de diferentes factores en el éxito de la obtención de imágenes 3/4D mediante el coeficiente de contingencia.Resultados. En relación a la edad gestacional, la mejorcalidad de imagen se obtiene en el tercer trimestre incipiente, aunque sin observar diferencias estadísticamente significativas. Respecto a las condiciones fetales, se observan diferenciasestadísticamente significativas en relación a laposición fetal, dorso fetal y volumen de líquido amniótico. La máxima puntuación se obtiene en situación longitudinal y presentación cefálica, en dorso fetal posterior y en condiciones de polihidramnios. No se demuestra una correlación estadísticamente significativa entre la calidad de imagen obtenida y el índice de masa corporal (IMC). En relación a la experiencia en 3/4D del ecografista: a) la máxima calidad de imagen se correlaciona con el nivel de experiencia del operador;b) se observa una correlación significativa e inversaentre le nivel de experiencia y el grado de dificultad de la exploración ecográfica, y c) no se observa correlación entre el nivel de experiencia y el grado de satisfacción materna tras la exploración 3/4D. En tecnología 3/4D y para un experto en ecografía 2D puede conseguirse una óptima calidad de imagen tras una curva de aprendizaje de 53 exploraciones ecográficas (rango: 34-70). Conclusiones. En relación a la ecografía obstétrica3/4D, la mejor calidad de imagen se obtiene en el tercer trimestre incipiente, en situación longitudinal y presentación cefálica, en dorso posterior y poli o normoamnios. El IMC no influye en la calidad de la imagen. Se demuestra una significativa correlación positiva entre la experiencia del operador y la calidad de imagen obtenida, y negativa entre aquélla y el grado de dificultad de la exploración. No se observacorrelación entre el nivel de experiencia y el grado de satisfacción materna tras la exploración 3/4D. El mínimo número de ecografías 3/4D necesarias para que un experto en ecografía 2D pueda considerarse competente se sitúa en 53 exploraciones, con un rango entre 34 y 70, aunque existen limitaciones en el uso de dicha tecnología pesar de la experiencia del operador

Objective. To explore several factors impact, particularlythe gestational age (GA), previous sonographer’sexperience, fetal conditions and body mass index (BMI),on the 3/4D US success. To explore the learning curve of 3/4DUS for experts in conventional two-dimensional ultrasound (2DUS). Methods. An overall of 1,000 routine prenatal scans were included, randomized selected, considering any gestational age or indication for referral except fetal malfromation. Scans were performed in our private Unit with Voluson 730 Expert by nine experts in 2DUS. The 3/4DUS expertise is categorized in level I (no experience), level II (short/medium experience) and level III (long experience). After a 2D detailed examination of the fetal anatomy, 3/4DUS was obtained in all cases consent about the objectives of the 2DUS and 3D images were obtained prior to scan. After the sonographic examination, the physician performing the scan completed a form with the clinical and technical details and the subjective qualification of the images. An independent observer was considered as a gold standard, completing in each case another blind form assessing the qualification of the 3D images. We consider the impact of several factors on the 3/4DUS success, particularlygestational age, previous sonographer’s experience,fetal conditions and BMI, by using the contingency coefficient. Obesity is considered when BMI is higher than 30. Results. Considering the impact of GA, the highest quality image scores were obtained at early third trimester. According to fetal conditions during the exploration, the highest quality scores were obtained in cephalic presentation, posterior spine and normo or polyhydramnios, all of them with statistical significance results. No statistically significant correlation between body mass index and quality images was observed. Considering physician’s experience impact: a) the highest image quality scores were obtained by the most experienced group. There is a statistical significant improvement in quality images when the highest level of expertise is reached; b) there is a statistical significant negative correlation between expertise and level of difficulty, and c) there is no correlation between level of expertise and maternal satisfaction. We analyze how long it takes to improve the 3/4D level and we create a learning curve of 3/4D technique:from a mean of 53 scans onwards (CI 95%: 34-70)we can start to get an acceptable 3/4DUS quality image.Any conditioning factor has a low impact on image quality,taking into account that 3D expertise level is the mostrelevant parameter (contingency coefficient of 0.2) and the BMI the least one (contingency coefficient of 0.09).Conclusions. The highest 3/4D quality scores wereobtained at early third trimester, cephalic presentation,posterior spine and poly or normoamnios. Statisticallysignificant positive correlation between level of expertise and quality images was observed. No statistically significant correlation between BMI and quality images was observed. Considering the impact of physician’s experience in 3/4DUS, the highest quality scores were obtained by the most experienced group, with no differences observed in maternal satisfaction. The learning curve of 3/4D US shows a mean of 53 scans to start getting acceptable images

The antenatal development of fetal behavioral patterns assessed by four-dimensional sonography.

The investigation of fetal intrauterine activities has been enabled by the development of two-dimensional ultrasound. It has been shown that the earliest signs of fetal motor activity can be in the late embryonic period, and that the characteristics of fetal motor patterns change constantly throughout gestation. During the first trimester of pregnancy, the repertoire and frequency fetal movement patterns constantly expand, whereas the second and third trimesters are characterized by the progressive organization of fetal activities into complex and clearly distinct behavioral patterns. The comparison of real time ultrasonic studies of fetal behavior with the morphological studies of fetal brains has revealed that the appearance of new behavioral patterns or the transition of existing patterns directly reflect the complex neurodevelopment processes. It has been suggested that the assessment of fetal behavioral patterns could give us insight into the integrity of fetal central nervous system and enable the early detection of cerebral dysfunctions. The development of a new ultrasonic technique, four dimensional sonography, could represent a significant improvement in the assessment of fetal behavior. According to the preliminary results, this new technique could open a new perspective for the investigations of fetal behavioral patterns and contribute significantly to our better understanding of complex neurodevelopmental events. The most important neurodevelopmental events, the basic technology of 4D ultrasound and its application in the assessment of functional development of fetal central nervous system will be the subject of this review.