Fetal imaging of the chest

Abstract

Ultrasonography (US) is the screening method of choice for the evaluation of the fetal airway and chest. It is safe, inexpensive and easily performed. Advances in US technique including higher resolution transducers, Doppler and 3D/4D imaging have allowed for improved assessment of the congenital thoracic masses. The assessment of the fetal chest by US, however, is operator dependent and evaluation may be limited due to fetal position, maternal obesity, overlying bone and/or oligohydramnios. Ultrasound evaluation is sensitive in the diagnosis of many prenatal lung lesions but has low specificity. Magnetic resonance imaging (MRI) is an alternative modality that uses no ionizing radiation, has excellent tissue contrast, a large field of view, is not limited by obesity or overlying bone and can image the fetus in multiple planes regardless of fetal lie. Faster scanning techniques allow studies to be performed without sedation in the second and third trimester with minimal motion artifact. Fetal MRI helps confirm the presence of masses identified by US, can delineate anatomy such as the trachea not visualized by US and may demonstrate additional subtle anomalies. Advances in US and MRI have improved our ability to accurately diagnose fetal airway and chest anomalies and furthered our understanding of the evolution of fetal lung lesions.