M. Segata

Middle cerebral artery peak systolic velocity: Technique and variability

Assessment of the middle cerebral artery (MCA) peak systolic velocity (PSV) can accurately diagnose fetal anemia and has decreased the number of invasive procedures, such as amniocentesis and cordocentesis. The objective of this investigation was to evaluate the intraobserver and interobserver variability as a measure of reproducibility of MCA PSV. The technique of correctly sampling this vessel is described.

Diagnosis of midline anomalies of the fetal brain with the three‐dimensional median view

To investigate the effectiveness of a simplified approach to the evaluation of the midline structures of the fetal brain using three‐dimensional (3D) ultrasound.

A novel technique for visualization of the normal and cleft fetal secondary palate : Angled insonation and three-dimensional ultrasound

To evaluate the effectiveness of a novel approach to the visualization of the fetal secondary palate using three‐dimensional (3D) ultrasound.

Prenatal diagnosis of open and closed spina bifida

To identify criteria useful for differentiating closed from open spina bifida antenatally.

Three‐dimensional ultrasound examination of the fetal central nervous system

The technique used to obtain an ultrasound volume is adequately described by three elements: (1) the section that is used to start the acquisition of the volume (referred to in the following as the ‘start’ scan); (2) the angle of rotation of the mechanical sweep of the motorized probe; and (3) the quality of the acquisition that can be varied by the operator and depends on the number of sections obtained during the acquisition. Both the angle of rotation and the quality of the volume influence the acquisition time and, when this is too long, the probability of movement artifacts increases. Tailoring the size and quality of the volumes to the specific diagnostic requirements is important because it increases the efficiency of the scan. In the following we provide information for each of the applications discussed. The modalities for the analysis of ultrasound volumes have been described in depth previously4,16,17. The multiplanar mode is most frequently used for assessment of the fetal CNS6,10,13,14. With this mode of display, the plane parallel to the acquisition plane or ‘start’ appears in the upper left corner of the screen and is identified with the letter A; the plane perpendicular to A but parallel to the ultrasound beam is identified with the letter B and appears in the upper right corner. The plane that is both perpendicular to the ‘start’ scan and the ultrasound beam is defined as C, and is frequently referred to as the coronal plane17 (Figure 1). The terminology may sound confusing at times. As discussed later, when dealing with the fetal brain, the coronal plane of the volume typically demonstrates a sagittal or axial section of the fetal head13. Although 3D ultrasound imaging can be used in many ways to evaluate the fetal (CNS), we have found that in practice there are mainly two useful applications: the multiplanar analysis of volumes obtained with an axial approach6,13 and the multiplanar analysis of volumes obtained from a sagittal or coronal approach12,14. 3D ultrasound examination can assist in evaluation of the spine18 and is particularly helpful in early neurosonographic studies1–3,5,19. It may also be used to improve the quality of two-dimensional (2D) images. These aspects are described separately below.

Accurate neurosonographic prediction of brain injury in the surviving fetus after the death of a monochorionic cotwin

To assess the feasibility of the prenatal diagnosis using fetal neurosonography of brain injuries in the surviving fetus after the demise of a monochorionic cotwin.

Fetal anemia: new technologies.

Purpose of review The purpose of this review is to summarize recently published studies on noninvasive diagnosis of fetal anemia in order to give recommendations for the use of these new tools. Recent findings Red cell alloimmunization remains one of the most common causes of fetal anemia. Amniocentesis and cordocentesis have been used for many years to diagnose fetal anemia due to red cell aloimmunization. These techniques, however, are invasive and many complications are associated with their use. Noninvasive diagnosis of fetal anemia has been performed with Doppler ultrasonography. Based on robust data, several authors recommend the use of middle cerebral artery peak systolic velocity in the management of fetuses at risk for anemia because of red cell alloimmunization. This Doppler parameter can also diagnose fetal anemia due to other conditions. Summary Middle cerebral artery peak systolic velocity appears to be the best test for the noninvasive diagnosis of fetal anemia. It is important to emphasize that training of sonographers and sonologists is the ‘conditio sine qua non’ for the correct sampling of the middle cerebral artery.

The prognostic role of uterine artery Doppler studies in patients with late-onset preeclampsia

OBJECTIVE To evaluate the usefulness of uterine artery Doppler in the prediction of outcome in patients with late-onset preeclampsia. STUDY DESIGN Patients with late-onset preeclampsia underwent Doppler interrogation of the uterine arteries. Patients with abnormal uterine artery Doppler were compared with those who had a normal uterine artery Doppler. RESULTS Ninety-nine patients were included in the study group. Abnormal uterine artery Doppler group presented significantly lower gestational age at admission (36.1 +/- 2.1 weeks vs 37.2 +/- 1.9 weeks; P < .005), lower gestational age at delivery (36.5 +/- 1.9 weeks vs 37.7 +/- 1.7 weeks; P < .005), lower birthweight (2429 +/- 590 g vs 3013 +/- 597 g; P < .0001), and a higher admission rate to neonatal intensive care unit (17/51 vs 6/48; odds ratio, 3.5; 95% confidence interval, 1.2-9.5). No significant difference in the occurrence of maternal complications (10/51 vs 6/48; odds ratio, 1.7; 95% confidence interval, 0.5-4.9) was registered. CONCLUSION Women with late-onset preeclampsia show a higher risk of perinatal complications if uterine resistance is increased although maternal outcome does not seem to be related to Doppler findings.

Inversion mode spatio-temporal image correlation (STIC) echocardiography in three-dimensional rendering of fetal ventricular septal defects

We read with interest the report of Yagel et al.1 addressing the use of four-dimensional (4D) color Doppler ultrasound implemented by spatio-temporal image correlation (STIC) technology in prenatal imaging of a ventricular septal defect (VSD). In their recent paper, an isolated muscular VSD is nicely documented in a 23-week fetus by means of 4D color STIC echocardiography. Diastolic shunting of blood flow through the defect is accurately displayed on a volume-rendered image of ventricular septum, whose reconstruction is carried out alternatively on coronal, axial and sagittal planes. We report here a case of an isolated VSD that was demonstrated in a mid-trimester fetus and confirmed at postnatal follow-up. A 40-year-old nulliparous woman had been referred to our ultrasound unit at 21 weeks of gestation for a detailed anomaly scan, including fetal echocardiography due to her advanced age. Extracardiac anatomy appeared unremarkable. During standard twodimensional echocardiography the suspicion of a VSD was raised by detection of color turbulence across the ventricular septum in the four-chamber view. Based on this finding, detailed imaging of the fetal heart was carried out using 4D STIC color technology. The volume dataset was acquired by a 10-s transverse sweep of 25 degrees through the fetal chest at the level of the fourchamber view. Volume reconstruction of the fetal heart was achieved in color mode focusing on the ventricular septum where a discontinuity was confirmed by diastolic shunting of blood across it (Figure 1). Further confirmation of previous findings was provided by the recently introduced inversion mode algorithm. Through this latter 4D ultrasound rendering option, blood flow shunting across the VSD was depicted as a hyperechogenic flap bridging the two ventricles in the diastolic phase of the cardiac cycle (Figure 2). Furthermore, by measuring in diastole the depth of the bridge between the ventricles (Figure 3), the defective area on the ventricular septum could be derived ((0.27/2)2 × 3.14 = 0.057 mm2). 4D echocardiography implemented by STIC technology has been recently introduced as an adjunctive option in prenatal imaging of congenital heart diseases2. As suggested by the acronym itself, STIC allows multiplanar view and volume rendering of moving structures such as fetal heart. Thanks to this algorithm, following a dynamic acquisition of a volume dataset including fetal heart, a single cardiac cycle is virtually reconstructed according to heart rate with fundamental section planes being displayed Figure 1 Volume reconstruction of four-chamber view by color spatio-temporal image correlation echocardiography: diastolic shunting through the interventricular septum is clearly depicted suggesting a ventricular septal defect (arrow).

Sonographic Diagnosis of Congenital Anomalies During the First Trimester

Current ultrasound technology allows an examination of fetal anatomy and the detection of anomalies at 12-15 weeks. Studies assessing the accuracy of early sonographic diagnosis prior to 15 weeks of pregnancy were reviewed. In expert hands the detection rate is about 40 per cent for major extra-cardiac anomalies and 65 per cent for major cardiac defects. However, due to technical and practical limitations, sonographic assessment of fetal anatomy in the first trimester cannot replace the midtrimester scan and should be restricted to couples whose fetus is at increased risk for malformation.