Search

Objectives The fetal thymus gland has been shown to involute in response to intrauterine infection, and therefore could be used as a non-invasive marker of fetal compartment infection. The objective of this study was to evaluate how accurately 2D ultrasound-derived measurements of the fetal thymus reflect the 3D volume of the gland derived from motion corrected MRI images. Study design A retrospective study was performed using paired ultrasound and MRI datasets from the iFIND project ( http://www.ifindproject.com ). To obtain 3D volumetry of the thymus gland, T2-weighted single shot turbo spin echo (ssTSE) sequences of the fetal thorax were acquired. Thymus volumes were manually segmented from deformable slice-to-volume reconstructed images. To obtain 2D ultrasound measurements, previously stored fetal cine loops were used and measurements obtained at the 3-vessel-view (3VV) and 3-vessel-trachea view (3VT): anterior-posterior diameter (APD), intrathoracic diameter (ITD), transverse diameter (TD), perimeter and 3-vessel-edge (3VE). Inter-observer and intra-observer reliability (ICC) was calculated for both MRI and ultrasound measurements. Pearson correlation coefficients (PCC) were used to compare 2D-parameters with acceptable ICC to TV. Results 38 participants were identified. Adequate visualisation was possible on 37 MRI scans and 31 ultrasound scans. Of the 30 datasets where both MRI and ultrasound data were available, MRI had good interobserver reliability (ICC 0.964) and all ultrasound 3VV 2D-parameters and 3VT 3VE had acceptable ICC (>0.75). Four 2D parameters were reflective of the 3D thymus volume: 3VV TD r = 0.540 (P = 0.002); 3VV perimeter r = 0.446 (P = 0.013); 3VV APD r = 0.435 (P = 0.110) and 3VT TD r = 0.544 (P = 0.002). Conclusions MRI appeared superior to ultrasound for visualization of the thymus gland and reproducibility of measurements. Three 2D US parameters, 3VV TD, perimeter and 3VT APD, correlated well with TV. Therefore, these represent a more accurate reflection of the true size of the gland than other 2D measurements, where MRI is not available.

Background To establish the normal reference range of fetal thorax by two-dimensional (2D) and three-dimensional (3D) ultrasound VOCAL technique and evaluate the application in diagnosing fetal thoracic malformations. Methods A prospective cross-sectional study was undertaken involving 1077 women who have a normal singleton pregnancy at 13–40 weeks gestational age (GA). 2D ultrasound and 3D ultrasound VOCAL technique were utilized to assess fetal thoracic transverse diameter, thoracic anteroposterior diameter, thoracic circumference, thoracic area, lung volume, thoracic volume and lung-to-thoracic volume ratio. The nomograms of 2D and 3D fetal thoracic measurements were created to GA. 50 cases were randomly selected to calculate intra- and inter-observer reliability and agreement. In addition, the case groups including congenital skeletal dysplasia (SD) (15), congenital diaphragmatic hernia (CDH) (30), pulmonary sequestration (PS) (25) and congenital cystic adenomatoid malformation (CCAM) (36) were assessed by the nomograms and followed up subsequently. Results Both 2D and 3D fetal thoracic parameters increased with GA using a quadratic regression equation. The intra- and inter-observer reliability and agreement of each thoracic parameter were excellent. 2D fetal thoracic parameters could initially evaluate the fetal thoracic development and diagnose the skeletal thoracic deformity, and lung volume, thoracic volume and lung-to-thorax volume ratio were practical to diagnose and differentiate CDH, PS and CCAM. Conclusion We have established the normal fetal thoracic reference range at 13–40 weeks, which has a high value in diagnosing congenital thoracic malformations.

Although relatively uncommon, congenital abnormalities in the thorax are important because of the potential effect on lung growth as well as the effect of the intrinsic abnormality. How to cite this article Ljubic A, Bozanovic T. The Fetal Thorax. Donald School J Ultrasound Obstet Gynecol 2017;11(3):210-224.

Fetal thorax evaluation through ultrasound is a fundamental step of the morphological examination. The noncardiac thoracic malformations (basically pulmonary and diaphragmatic defects) must always be investigated, owing to high perinatal morbidity and mortality rates of these abnormalities.

Several disorders may present as cystic complex lesions of the fetal thorax, both with benign and malignant behavior. As a consequence, their detection may pose diagnostic, therapeutic, and parental counseling dilemmas. We describe a neonate with a congenital Askin tumor, diagnosed at the 37th week of gestation and treated after birth. Counseling and treatment challenges are discussed.

Objectives. To investigate the detection rate of major fetal heart defects in a low-risk population implementing routine use of color Doppler. Material and Methods. In a prospective observational study, all women undergoing fetal heart scanning (including 6781 routine examinations in the second trimester) during a three-year period were included. First a gray-scale scanning was performed including assessment of the four-chamber view and the great vessels. Thereafter three cross-sectional planes through the fetal thorax were assessed with color Doppler. Results. Thirty-nine fetuses had major heart defects, and 26 (67%) were prenatally detected. In (35%) of cases the main ultrasound finding was related to the use of color Doppler. The survival rate of live born children was 91%. Conclusions. Routine use of color Doppler in fetal heart scanning in a low-risk population may be helpful in the detection of major heart defects; however, still severe malformations were missed prenatally.

There are few 3D well-documented studies about thoraco- abdominal malformations, except for the evaluation of fetal lung volume. Three-dimensional ultrasound provides additional diagnostic information for the evaluation of fetal thorax both for the diagnosis of skeletal anomalies and the biometric measurements of lungs. 3D adds few information about the diagnosis of gastrointestinal malformations, but 3D images are an effective tool to make a careful advice with parents and pediatric surgeons, especially in fetuses with anterior wall defects. Until now its use must be reserved in a research setting and offered to high-risk patients in order to understand which role 3D may play in the study of thoraco-abdominal malformations as a screening or diagnostic tool.

Fetal thoracic anomalies often lead to pulmonary hypoplasia with subsequent fetal or neonatal demise. Therefore, in utero sonographic identification of these anomalies is important. Unlike cardiac anomalies, most noncardiac thoracic abnormalities are easily detected with ultrasound. An unusually small thorax is usually obvious to the experienced sonographer, and thoracic masses are commonly observed on the routinely obtained four-chamber view of the heart. This article reviews the many causes of pulmonary hypoplasia with an emphasis placed on thoracic masses. Many examples of pathological fetal thoracic conditions are provided as well as a listing of differential considerations with regard to sonographic appearances of chest masses.

Prenatal sonography provides a sensitive detection of most fetal thoracic pathologies. However, the specificity and reliability in the diagnosis as well as prediction of postnatal outcome may be further optimized by fetal MR imaging. Due to the excellent tissue contrast of fetal MRI and the ability to provide information on the chemical composition of certain lung lesions using different MR sequences, this imaging modality can add further diagnostic information, which may be even superior to the commonly used postnatal imaging procedures. Thus, fetal MR of thoracic pathologies finally constitutes a valuable preoperative imaging tool. This chapter generally reviews the most frequently encountered thoracic pathologies of the fetus focusing on pulmonary hypoplasia and cystic lung lesions and describes their MR imaging appearance on a variety of MR sequences.

Purpose of review To describe the state of the science of three-dimensional/four-dimensional ultrasound (3D/4DUS) applications to fetal medicine. Recent findings 3D/4DUS applications are many and varied. Their use in fetal medicine varies with the nature of the tissue to be imaged and the challenges each organ system presents, versus the advantages of each ultrasound application. We will here describe the research and clinical use of 3D/4DUS applications in fetal medicine today, as they are applied to greatest benefit to various organ systems. Summary 3D/4DUS has been extensively applied to the study of the fetus. Fetal applications include all types of anatomical assessment, morphometry and volumetry, as well as functional assessment. 3D/4DUS provides many advantages in fetal imaging; however, its contribution to improving the accuracy of fetal scanning over rates achieved with 2DUS, remains to be established.

Whether in fetal or postnatal life, echocardiographic diagnosis is based on moving images. With recent advances in ultrasound systems, storing multiple digital frames and clips with superb image quality has become a reality. These advances have brought innovative applications into the clinical field and can be integrated into powerful multimedia presentations for teaching purposes. Sections of cardiac specimens are usually compared with corresponding sections in echocardiography textbooks. These sections are mainly obtained from isolated hearts, due to ease and speed of acquisition. Nevertheless, sections of the whole body are a better tool with which to understand the relationship between cardiac and extracardiac structures. This understanding is particularly important in fetal echocardiography, where the number of visible structures around the heart is much greater and the approaches to the fetal thorax are more variable. The DVD accompanying the book presents morphological images from tomographic sections of the whole fetal body, as well as high-quality dynamic echocardiographic images of normal fetuses and of some of the most common congenital heart defects. The extraordinary amount of information provided in this work makes this publication a highly useful resource for obstetricians, sonographers, and pediatric cardiologists. © Springer-Verlag Italia 2008. All rights are reserved.

High resolution ultrasound has allowed increased definition and detailed study of the fetal thorax. From the second trimester, congenital anomalies arising from or involving the fetal chest can be visualized. Early detection and diagnosis of fetal intrathoracic abnormalities are rapidly becoming an integral part of modern obstetrical care and neonatal management. The potential exists to diagnose most intrathoracic anomalies before the 20th week of pregnancy.

Congenital chylothorax is an uncommon condition, resulting from lymphatic accumulation in the fetal thorax; affected siblings are extremely rare. We report a woman who delivered 3 children with congenital chylothorax; each case was managed differently, including the use of ex utero intrapartum treatment (EXIT) with the third pregnancy.

We observed two cases of anatomic and functional abnormalities of the lower esophagus associated with congenital diaphragmatic hernia (Bochdalek's hernia). In the first case, severe dilation and gastroesophageal reflux were noted during postoperative treatment. In the second, atresia at the anal end of the dilated lower esophagus was found and esophagogastrostomy was later performed. These cases suggest that kinking of the esophagocardial (EC) junction that occurred during intestinal herniation into the fetal thorax might have caused lower esophageal ectasia and/or atresia of the EC junction.

Increasingly, paediatric cardiologists are called upon to diagnose cardiac malformations prenatally. In the main, the types of malformation seen during fetal life will be similar to those documented postnatally, but the frequency with which they are encountered, as well as the views that can be used for diagnosis, will be different. This review aims to describe the anatomic spectrum of malformations seen in 917 fetal hearts examined consecutively following prenatal diagnosis. The distribution of anomalies is illustrated in terms of a simple sweep through the fetal thorax passing from the four-chamber plane to the outflow tracts, and then to more cranial views of the mediastinum. Two-thirds of the anomalies described would have been detectable in the four-chamber plane. Some, such as tricuspid valvar abnormalities, will alter the normal appearances of the four-chambers dramatically. In terms of the overall spectrum, however, such obvious abnormalities only form a minor part of the total number. Others, such as atrioventricular septal defect, will often require closer inspection of intracardiac anatomy, but will make up a large proportion of the entire cohort. Up to one third of the anomalies in the series would have required views more cranial to the four-chamber plane of section. In these, it would have been necessary to examine the nature of the left ventricular outflow tract, the crossing of the two outflows, or else the arterial arches in order to secure detection. In the fetus, these and other planes must be considered by the echocardiographer in order completely to detect and document the entire spectrum of cardiac abnormalities likely to be encountered.

A series of 25 fetuses in which ARSA was diagnosedusing transverse views was found in a group of pregnant women(between 16–36 weeks of pregnancy) attending our Fetal MedicineUnit for ultrasound examination (Figure 1A). After its detection ina transverse view, fetal ARSA was visualized in the coronal view bysweeping the probe at the level of the fetal thorax in a coronal planeanterior to the spine (Figure 1B). In this plane we were able to seethe thoracic descending aorta and the origin of the aberrant vesselin a distal position. Color and Pulsed Doppler was used to definethe course of the ARSA and distinguish it from other vessels.

The antenatal diagnoses of three cystic fetal thoracic abnormalities are described. The ultrasound findings led to early postnatal surgical attention and prompt therapeutic intervention. This report will discuss the differential diagnoses of cystic lesions of the fetal chest and stress the importance of antenatal identification.

Fetal thoracic circumference and thoracic length measurements were obtained by ultrasonographic examination on 576 women between 16 and 40 weeks gestation. Nomograms for thoracic circumference and thoracic length with respect to gestational age were developed. Growth of both thoracic parameters was observed to be linear throughout gestation. In normal pregnancy the ratios of thoracic circumference to abdominal circumference and thoracic length to humerus length remained virtually constant at 0.89 and 0.93, respectively.

Measurements of minimum thicknesses, in a four-layer, overlying tissue model, on 22 pregnancies between 15 and 20 weeks gestation, yielded a global minimum and a mean of the minimum total thickness per patient of 1.7 and 2.9 cm, respectively, and a minimum and mean subcutaneous fat thickness of 0.7 and 1.4 cm. Conservative calculations of the minimum attenuation per patient, at 3.5 MHz indicated that less than 2.5% of 15 to 20 week pregnancies should fall below the lower 95% prediction line of: Attenuation (dB) = 0.10 X Maternal Weight (kg) - 3.0. The smallest calculated attenuation for any of the 21 subjects was 0.8 dB MHz-1 indicating just under a factor of two protection at 3.5 MHz of proximal fetal tissues compared with ultrasound intensities measured in water. This value is lower than those generally used in the past. The knowledge of distributions of transducer-to-fetal distances and thicknesses of overlying tissues is also important for improvement of image quality. Measurement of minimum depth of the anterior fetal thorax in 57 examinations of 25 to 40 week fetuses yielded minimum and mean values of 2.5 and 4.1 cm, respectively.

Summary The biparietal diameter and area of the fetal skull, and the area of the fetal thorax, were measured by ultrasonic scanning in 68 patients in the seven days prior to delivery. These parameters and various expressions based on the skull and thoracic areas were related to birth weight. It was concluded that the skull and thoracic areas multiple (STAM) index was a more efficient predictor of birth weight than the biparietal diameter.

Anencephaly can be diagnosed using real-time ultrasonography. This enables visualization of the fetal movements and facilitates identification of the fetal parts, making certain the exact orientation of the fetus. Thus, the negative finding of the lack of fetal calvarium, as well as the positive finding of insufficient space for a calvarium to exist between the fetal thorax and the uterine wall, can be confidently ascertained. One can then be certain that a fetal head is not being missed by the ultrasound beam, as is possible with a rapidly moving fetus using B-mode ultrasound.

In the fortnight following birth, the form and dimensions of the thorax undergo a series of peculiar changes which are dependent on a number of different factors. One of these changes, the increase in the horizontal circumference of the chest accompanying the first inspiration, is well known, but others, which are less marked and more variable, have apparently passed unnoticed. The following account of the changes in the form of the thorax of the new-born is based on measurements of the thoraces of late fetuses and full term still-born children, on observations of living infants on the first, third, fifth, seventh, tenth and twelfth days after birth, and on a number of observations on the horizontal chest circumference immediately before and after the first inspiration. The observations on the dimensions of the fetal thorax were made by Dr. L. A. Calkins as a part of an extensive study on the