Chest, Foetal imaging, Thorax, MR, Diagnostic procedure, Congenital, Foetus, Retrospective, Observational, Not applicable
J. Fávero Prietto dos Santos, M. C. Barreto da Silva Barros, L. Vieira Targa, A. P. V. F. Benites Sperb, F. Fagundes Bassols, J. A. Bianchi Telles; Porto Alegre/BR
Fetal ultrasound scan remains the modality of choice to fetuses’ morphological evaluation in both low-risk and high-risk pregnancies because of its easy accessibility and low cost. This applies especially to the second-trimester scan, considering the late development of many anatomical structures and its anomalies that make early detection inaccessible. However, antenatal ultrasound has some limitations, such as the need for personal experience and training, maternal obesity, severe oligohydramnios, fetal position, limited field-of-view, lower tissue resolution and method-related artifacts.
Unlike ultrasound, fetal MRI is a complementary exam used to confirm or obtain additional information regarding fetal anatomy, mainly with complex cases, multiple malformations or diagnostic uncertainties. MRI allows the radiologist a wide field-of-view and high tissue resolution, providing a panoramic assessment of the fetal chest and an accurate differentiation of its contents. Thereby, fetal MRI may provide additional diagnostic and prognostic information and it is vital in uncertain diagnostic scenarios, modifying patient management.
The spectrum of congenital chest malformations can range from asymptomatic lesions to great masses requiring surgical intervention, therefore it is important to recognize imaging findings of fetal thoracic anomalies, which are divided into three main categories (bronchopulmonary anomalies, vascular anomalies and both combined). Other types of malformations may have a mass effect causing secondary changes in lung development, such as congenital diaphragmatic hernia.
Therefore, it is important to evaluate diaphragm continuity, presence of solid or cystic masses and their arterial supply, mass effect on mediastinal structures and other complications (e.g. hydrops, pleural effusion), also associated anomalies. Fetal MRI indications for evaluation of thoracic malformations, method advantages and limitations are described in figure 2.