Assessment of the fetal lungs in utero

Abstract

Antenatal diagnosis of abnormal pulmonary development has improved significantly over recent years because of progress in imaging techniques. Two-dimensional ultrasound is the mainstay of investigation of pulmonary pathology during pregnancy, providing good prognostication in conditions such as congenital diaphragmatic hernia; however, it is less validated in other high-risk groups such as those with congenital pulmonary airway malformation or preterm premature rupture of membranes. Three-dimensional assessment of lung volume and size is now possible using ultrasound or magnetic resonance imaging; however, the use of these techniques is still limited because of unpredictable fetal motion, and such tools have also been inadequately validated in high-risk populations other than those with congenital diaphragmatic hernia. The advent of advanced, functional magnetic resonance imaging techniques such as diffusion and T2* imaging, and the development of postprocessing pipelines that facilitate motion correction, have enabled not only more accurate evaluation of pulmonary size, but also assessment of tissue microstructure and perfusion. In the future, fetal magnetic resonance imaging may have an increasing role in the prognostication of pulmonary abnormalities and in monitoring current and future antenatal therapies to enhance lung development. This review aims to examine the current imaging methods available for assessment of antenatal lung development and to outline possible future directions.

Keywords: fetal; magnetic resonance imaging; pulmonary development; ultrasound.

Figure 1

3T images of low-risk fetus at 30 weeks before and after applying DSVR DSVR: Deformabale slice-to-volume registration.

Figure 2

T2 (top) and T2* (bottom) aligned maps of a healthy fetus at 35 weeks’ gestation scanned on a 3T MRI scanner 3T MRI, 3 Tesla magnetic resonance imaging.

Figure 3

Ultrasound and MR images comparison with measurement diagrams of CDH, CPAM, and pleural effusion cases CDH, congenital diaphragmatic hernia; CPAM, congenital pulmonary airway malformation; CVR, congenital pulmonary airway malformation volume ratio; FETO, fetoscopic endoluminal tracheal occlusion; MRI, magnetic resonance imaging.