Usefulness of prenatal magnetic resonance imaging in differential diagnosis of fetal congenital cystic adenomatoid malformation and bronchopulmonary sequestration.

Background: Congenital cystic adenomatoid malformation (CCAM) and bronchopulmonary sequestration (BPS) are the most common lung diseases in fetuses. There are differences in the prognosis and treatment of CCAM and BPS, and the clinical diagnosis and treatment plan is usually prepared prior to birth. Therefore, it is quite necessary to make a clear diagnosis before delivery. CCAM and BPS have similar imaging features, and the differentiation mainly relies on the difference in supply vessels. However, it is hard to distinguish them due to invisible supplying vessels on some images.

Aim: To explore the application value of magnetic resonance imaging (MRI) in the differential diagnosis of fetal CCAM and BPS.

Methods: Data analysis for 32 fetuses with CCAM and 14 with BPS diagnosed by prenatal MRI at Huzhou Maternal and Child Health Care Hospital and Anhui Provincial Children's Hospital from January 2017 to January 2020 was performed to observe the source blood vessels of lesions and their direction. Pathological confirmation was completed through CT examination and/or operations after birth.

Results: After birth, 31 cases after birth were confirmed to be CCAM, and 15 were confirmed to be BPS. The CCAM group consisted of 21 macrocystic cases and 10 microcystic cases. In 18 cases, blood vessels were visible in lesions. Blood supply of the pulmonary artery could be traced in eight cases, and in 10 cases, only vessels running from the midline to the lateral down direction were observed. No lesions were found in four macrocystic cases and one microcystic case with CCAM through CT after birth; two were misdiagnosed by MRI, and three were misdiagnosed by prenatal ultrasonography. The BPS group consisted of 12 intralobar cases and three extralobar cases. Blood vessels were visible in lesions of nine cases, in four of which, the systemic circulation blood supply could be traced, and in five of which, only vessels running from the midline to the lateral up direction were observed. Three were misdiagnosed by MRI, and four were misdiagnosed by prenatal ultrasonography.

Conclusion: CCAM and BPS can be clearly diagnosed based on the origin of blood vessels, and correct diagnosis can be made according to the difference in the direction of the blood vessels, but it is hard distinguish microcystic CCAM and BPS without supplying vessels. In some CCAM cases, mainly the macrocystic ones, the lesions may disappear after birth.