Comparison of matching by body volume or gestational age for calculation of observed to expected total lung volume in fetuses with isolated congenital diaphragmatic hernia

Prenatal lung volumes in congenital diaphragmatic hernia and their effect on postnatal outcomes

Lung volume measurement on fetal MRI is a component of the imaging workup for various prenatal conditions, but its use as a prognosticator has been most heavily studied in congenital diaphragmatic hernia (CDH). Pediatric radiologists who perform and interpret fetal MRI must be familiar with the technical aspects of lung volume measurement to guarantee accurate measurement and reporting. Variability in timing and type of measurement at different fetal centers also requires pediatric radiologists to be up-to-date with the literature and aware of their center's internal data. This paper provides both a how-to guide for measuring fetal lung volumes on MRI and a comprehensive review of the CDH outcome literature to serve as a convenient reference for the pediatric radiologist.

The role of magnetic resonance imaging in the diagnosis and prognostic evaluation of fetuses with congenital diaphragmatic hernia

In recent years, magnetic resonance imaging (MRI) has largely increased our knowledge and predictive accuracy of congenital diaphragmatic hernia (CDH) in the fetus. Thanks to its technical advantages, better anatomical definition, and superiority in fetal lung volume estimation, fetal MRI has been demonstrated to be superior to 2D and 3D ultrasound alone in CDH diagnosis and outcome prediction. This is of crucial importance for prenatal counseling, risk stratification, and decision-making approach. Furthermore, several quantitative and qualitative parameters can be evaluated simultaneously, which have been associated with survival, postnatal course severity, and long-term morbidity.

CONCLUSION

Fetal MRI will further strengthen its role in the near future, but it is necessary to reach a consensus on indications, methodology, and data interpretation. In addition, it is required data integration from different imaging modalities and clinical courses, especially for predicting postnatal pulmonary hypertension. This would lead to a comprehensive prognostic assessment.

WHAT IS KNOWN

• MRI plays a key role in evaluating the fetal lung in patients with CDH. • Prognostic assessment of CDH is challenging, and advanced imaging is crucial for a complete prenatal assessment and counseling.

WHAT IS NEW

• Fetal MRI has strengthened its role over ultrasound due to its technical advantages, better anatomical definition, superior fetal lung volume estimation, and outcome prediction. • Imaging and clinical data integration is the most desirable strategy and may provide new MRI applications and future research opportunities.

Congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a potentially severe anomaly that should be referred to a fetal care center with expertise in multidisciplinary evaluation and management. The pediatric radiologist plays an important role in the evaluation of CDH, both in terms of anatomical description of the anomaly and in providing detailed prognostic information for use in caring for the fetus and pregnant mother as well as planning for delivery and postnatal care. This article reviews the types of hernias, including distinguishing features and imaging clues. The most common methods of predicting severity are covered, and current fetal and postnatal therapies are explained. The author of this paper provides a handy reference for pediatric radiologists presented with a case of CDH as part of their daily practice.

Prenatal diagnosis and management of congenital diaphragmatic hernia

Congenital diaphragmatic hernia is characterized by failed closure of the diaphragm, thereby allowing abdominal viscera to herniate into the thoracic cavity and subsequently interfering with normal lung development. At birth, pulmonary hypoplasia leads to respiratory insufficiency and persistent pulmonary hypertension (PHT), that is lethal in up to 32% of patients. In isolated cases, the outcome may be predicted prenatally by medical imaging and advanced genetic testing. In those fetuses with a predicted poor outcome, fetoscopic endoluminal tracheal occlusion may be offered. This procedure is currently being evaluated in a global randomized clinical trial (www.TOTALtrial.eu). We are currently investigating alternative strategies including transplacental sildenafil administration to reduce the occurrence of persistent PHT.

Correlation of observed-to-expected total fetal lung volume with intrathoracic organ herniation on magnetic resonance imaging in fetuses with isolated left-sided congenital diaphragmatic hernia

OBJECTIVES

To assess using fetal magnetic resonance imaging (MRI) the relationship between the position of the stomach as well as the volume of herniation of organs into the thorax, and the observed-to-expected total fetal lung volume (o/e-TFLV), as a measure of pulmonary hypoplasia, in fetuses with isolated left-sided congenital diaphragmatic hernia (LCDH).

METHODS

This was a single-center retrospective study using archived MR images from fetuses > 20 weeks' gestation evaluated for isolated LCDH over an 11-year period between July 2002 and September 2013. We retrieved data on the gestational age at MRI, o/e-TFLV and liver position. Images were also reviewed by a single operator to determine retrospectively the position of the stomach as well as the proportion of the total thorax volume occupied by the herniated fetal liver, stomach and other viscera. Following confirmation of reproducibility, we assessed the correlation of intrathoracic organ volumes and stomach position with o/e-TFLV.

RESULTS

The study included 205 fetuses which underwent a total of 259 MR examinations. The reproducibility of organ volume measurements was excellent (intraclass correlation coefficient range, 0.928-0.997). The average time spent to obtain intrathoracic organ volumes ranged from 2.28 to 5.13 min. Of all herniated organ-to-thoracic volume ratios, the liver-to-thoracic volume ratio had the strongest correlation with o/e-TFLV (ρ = -0.429, P<0.0001). Stomach volume did not correlate, although, when categorized by the position and extent of stomach herniation, there was an inverse relationship to o/e-TFLV. No intrathoracic organ-to-thoracic volume ratio was related to gestational age.

CONCLUSIONS

We observed in fetuses with isolated LCDH an inverse relationship between lung volume and the amount of liver herniated as well as the position of the stomach in the chest.

Prenatal management of the fetus with isolated congenital diaphragmatic hernia in the era of the TOTAL trial

Congenital diaphragmatic hernia (CDH) may be isolated or associated with other structural anomalies, the latter with poor prognosis. The defect allows viscera to herniate through the defect into the chest, competing for space with the developing lungs. At birth, pulmonary hypoplasia leads to respiratory insufficiency and persistent pulmonary hypertension that is lethal in up to 30% of patients. When isolated, survival chances can be predicted by antenatal measurement of lung size and liver herniation. Chromosomal microarrays and exome sequencing contribute to understanding genetic factors underlying isolated CDH. Prenatal intervention aims at stimulating lung development, clinically achieved by percutaneous fetal endoscopic tracheal occlusion (FETO) under local anesthesia. The Tracheal Occlusion To Accelerate Lung growth trial (www.totaltrial.eu) is an international randomized trial investigating the role of fetal therapy for severe and moderate pulmonary hypoplasia. Despite an apparent increase in survival following FETO, the search for lesser invasive and more potent prenatal interventions must continue.