The right lung is affected by the CPAM and has increased in echogenicity relative to the left. There has also been the development of a small cystic space in the lung. Mass effect from the malformation displaces the left atrium.
The fetal MRI matches the ultrasound exam closely in appearance, with an enlarged and T2 hyperintense right lung. The cystic space is seen on the sagittal view.
Case Discussion
Congenital pulmonary airway malformation (CPAM) can be detected in utero with both ultrasound and MRI.
An important ratio when assessing a fetal CPAM is the ratio between the volume of the CPAM and the fetal head circumference (HC). The HC is essentially a surrogate for the fetal age.
A CVR >1.6 or a CPAM with a dominant cyst increases the fetal risk of fetal hydrops. In this case, the CVR <1.0.
Thanks to Steve Horii MD for this case.