Fetal ultrasound and magnetic resonance imaging: a primer on how to interpret prenatal lung lesions

Prenatal features of congenital peribronchial myofibroblastic tumor

Here, we report a case of a congenital peribronchial myofibroblastic tumor (CPMT). A 34-year-old primigravida was referred to our hospital at 31 gestation weeks because of suspected congenital pulmonary airway malformation (CPAM). Fetal ultrasonography showed a mass measuring 4.6 × 4.0 × 3.9 cm with mixed high and low echogenicity in the left lung, which was associated with microvascular blood flow in the tumor. Fetal magnetic resonance imaging (MRI) revealed a low-intensity left lobe lung lesion on a T2-weighted image. These findings suggested that the mass was a CPAM with atypical hypointense findings on MRI T2-weighted images or a rare primary pulmonary tumor, such as a CPMT. Unfortunately, the fetus died in utero at 34 gestation weeks due to cardiovascular failure, which could have resulted from direct encasement of the great vessels or cardiac compression due to rapid tumor growth. The autopsy findings confirmed the diagnosis of CPMT. Primary pulmonary tumors, such as CPMT, are extremely rare lung diseases that develop in utero. These tumors often rapidly grow during pregnancy, resulting in intrauterine fetal death. However, if the patient survives surgical mass resection, the prognosis is good. Given the adverse outcomes observed in our case, careful fetal monitoring is required in case of suspected CPMT during the third trimester of pregnancy. Moreover, in case the well-being of the fetus cannot be assured, immediate delivery should be considered, even in the preterm period, followed by surgery.

Congenital bronchogenic cyst: From prenatal diagnosis to postnatal management

OBJECTIVE

Bronchogenic cysts are rare congenital abnormalities, and usually asymptomatic until adulthood. We present a fetus prenatally diagnosed with a bronchogenic cyst, experiencing compression symptoms immediately after birth and underwent thoracoscopic surgery at 14 days old.

CASE REPORT

A 33-year-old primigravida had a suspicion of fetal tracheal cyst. Prenatal ultrasound scan revealed a cyst near the trachea at 23 weeks' gestation. Fetal MRI defined a cystic lesion in the upper mediastinum, displacing surrounding vessels. A 3,940 g girl was delivered vaginally at 38 weeks' gestation. Shortly after birth, she developed respiratory distress, and imaging revealed a mediastinal cyst compressing the trachea and esophagus. The cyst was successfully removed through video-assisted thoracoscopic surgery at 14 days old, and pathology confirmed it as a bronchogenic cyst. Follow-up images demonstrated well-aerated lungs. At present, this 1-year-old girl develops normally without respiratory symptoms.

CONCLUSION

Early detection in utero, accurate diagnosis, and timely management are crucial for bronchogenic cysts in neonates.

Prenatal Measurements of Congenital Lung Malformations: Can They Predict Postnatal Size?

INTRODUCTION

Prenatally diagnosed congenital lung malformations (CLMs) are monitored via ultrasound and measured by congenital pulmonary airway malformation volume ratios (CVRs) which can predict postnatal respiratory symptoms. This study compared CVR to postnatal lesion size to help guide prenatal counseling.

METHODS

A retrospective chart review evaluated the prenatal imaging and postnatal outcomes for patients who were prenatally diagnosed with CLMs and had a postnatal computed tomography (CT) scan at one institution.

RESULTS

Fifty-seven patients were included. Four had symptoms requiring urgent resection. The remaining were discharged and had clinic follow-up with CT scan to determine next steps: five had no identified lesions, eight had lesions whose diagnosis did not warrant an operation, and 40 had lesions whose diagnosis rendered size a factor in operative decision-making. Of these 40, 26/40 patients (65%) underwent elective resection (median maximum CVR 0.97; median lesion size 4 cm) and 14/40 patients (35%) were observed without resection (median maximum CVR 0.5; median lesion size 3 cm). There was a positive correlation between prenatal CVR and postnatal lesion size, with R-squared = 0.46. Maximum CVRs were better than last CVRs when predicting whether postnatal CT size would fall above or below our institution's level of recommended resection, with an area under the curve of 0.85 and a CVR cut-point of 0.61.

CONCLUSIONS

For newborns with asymptomatic CLMs, higher maximum CVRs correlated with larger size on postnatal CT. A maximum CVR ≤0.6 was correlated with a smaller postnatal CT size that may be eligible for nonoperative management. While these results are not intended to recommend surgery based on higher CVRs alone, this information could potentially be used to reassure expectant parents whose babies' prenatal imaging demonstrate lower maximum CVRs.

Enhancing Fetal Anomaly Detection in Ultrasonography Images: A Review of Machine Learning-Based Approaches

Fetal development is a critical phase in prenatal care, demanding the timely identification of anomalies in ultrasound images to safeguard the well-being of both the unborn child and the mother. Medical imaging has played a pivotal role in detecting fetal abnormalities and malformations. However, despite significant advances in ultrasound technology, the accurate identification of irregularities in prenatal images continues to pose considerable challenges, often necessitating substantial time and expertise from medical professionals. In this review, we go through recent developments in machine learning (ML) methods applied to fetal ultrasound images. Specifically, we focus on a range of ML algorithms employed in the context of fetal ultrasound, encompassing tasks such as image classification, object recognition, and segmentation. We highlight how these innovative approaches can enhance ultrasound-based fetal anomaly detection and provide insights for future research and clinical implementations. Furthermore, we emphasize the need for further research in this domain where future investigations can contribute to more effective ultrasound-based fetal anomaly detection.

Fetal Lung Interstitial Tumor (FLIT): Review of The Literature

Fetal lung interstitial tumor (FLIT) is an extremely rare pediatric lung tumor that shares radiological features with congenital pulmonary malformations (cPAM) and other lung neoplasms. A review of the literature, together with the first European case, are herein reported. A systematic and manual search of the literature using the keyword "fetal lung interstitial tumor" was conducted on PUBMED, Scopus, and SCIE (Web of Science). Following the PRISMA guidelines, 12 articles were retrieved which describe a total of 21 cases of FLIT, and a new European case is presented. A prenatal diagnosis was reported in only 3 out of 22 (13%) cases. The mean age at surgery was 31 days of life (1-150); a lobectomy was performed in most of the cases. No complications or recurrence of disease were reported at a mean follow-up of 49 months. FLIT is rarely diagnosed during pregnancy, may present at birth with different levels of respiratory distress, and requires prompt surgical resection. Histology and immunohistochemistry allow for the differentiation of FLIT from cPAM and other lung tumors with poor prognosis, such as pleuropulmonary blastoma, congenital peri-bronchial myofibroblastic tumor, inflammatory myofibroblastic tumor, and congenital or infantile fibrosarcoma.

Indications for magnetic resonance imaging of the fetal body (extra-central nervous system): recommendations from the European Society of Paediatric Radiology Fetal Task Force

The indications for fetal body MRI are amplifying because of the expanding possibilities of fetal and perinatal therapy. However, huge heterogeneity regarding the indications for fetal body MRI is seen among different European countries that is mostly related to local use of US, but also to local fetal MRI expertise and legislation on pregnancy termination. The purpose of this article is to summarize the precise indications for fetal MRI, excluding the central nervous system. MRI indications arise from the sonographic findings, based on the operator's experience and the various practices in the countries and institutions represented on the European Society of Paediatric Radiology Fetal Task Force. We also highlight the strengths and weaknesses of fetal US and MRI of the fetal body.

Surgical Management of Congenital Lung Malformations

Congenital lung malformations (CLMs) are commonly diagnosed prenatal lesions with varied natural history. Prenatal diagnosis and monitoring help to guide fetal interventions, delivery planning, and need for urgent perinatal surgical interventions. All prenatally diagnosed CLMs should be evaluated postnatally, typically with cross-sectional imaging, because many lesions persist despite the appearance of complete 'regression' in utero. Management of CLMs in asymptomatic infants weighs the surgical and anesthetic risk of prophylactic resection against the risk of expectant management, including the possibility of infection, malignant degeneration, and more complicated surgical resection later with loss of compensatory lung growth.

Fetal imaging of congenital lung lesions with postnatal correlation

Congenital lung lesions are a rare group of developmental pulmonary abnormalities that are often first identified prenatally on routine second-trimester US. Congenital pulmonary airway malformation (CPAM) is the most common anomaly while others include bronchopulmonary sequestration, congenital lobar overinflation, bronchogenic cyst and bronchial atresia. Clinical presentation is highly variable, ranging from apparent in utero resolution to severe mass effect with resultant hydrops fetalis and fetal demise. Differentiation among these lesions can be challenging because overlapping imaging features are often present. The roles of the radiologist are to identify key imaging findings that help in diagnosing congenital lung lesions and to recognize any ominous features that might require prenatal or perinatal intervention. High-resolution US and complementary rapid-acquisition fetal MRI provide valuable information necessary for lesion characterization. Postnatal US and CT angiography are helpful for lesion evaluation and for possible surgical planning. This article reviews the embryology of the lungs, the normal prenatal imaging appearance of the thorax and its contents, and the prenatal and neonatal imaging characteristics, prognosis and management of various congenital lung lesions.

Characterization of the Hyperintense Bronchus Sign as a Fetal MRI Marker of Airway Obstruction

Background Fetal MRI-based differential diagnosis of congenital lung malformations is difficult because of the paucity of well-described imaging markers. Purpose To characterize the hyperintense bronchus sign (HBS) in in vivo fetal MRI of congenital lung malformation cases. Materials and Methods In this retrospective two-center study, fetal MRI scans obtained in fetuses with congenital lung malformations at US (January 2002 to September 2018) were reviewed for the HBS, a tubular or branching hyperintense structure within a lung lesion on T2-weighted images. The frequency of the HBS and respective gestational ages in weeks and days were analyzed. Areas under the curve (AUCs), 95% CIs, and P values of the HBS regarding airway obstruction, as found in histopathologic and postnatal CT findings as the reference standards, were calculated for different gestational ages. Results A total of 177 fetuses with congenital lung malformations (95 male fetuses) and 248 fetal MRI scans obtained at a median gestational age of 25.6 weeks (interquartile range, 8.9 weeks) were included. The HBS was found in 79% (53 of 67) of fetuses with bronchial atresia, 71% (39 of 55) with bronchopulmonary sequestration (BPS), 43% (three of seven) with hybrid lesion, 15% (six of 40) with congenital cystic adenomatoid malformation, and 13% (one of eight) with bronchogenic cyst at a median gestational age of 24.9 weeks (interquartile range, 9.7 weeks). HBS on MRI scans at any gestational age had an AUC of 0.76 (95% CI: 0.70, 0.83; P = .04) for the presence of isolated or BPS-associated airway obstruction at histopathologic analysis and postnatal CT. The AUC of HBS on fetal MRI scans obtained until gestational age of 26 weeks (AUC, 0.83; 95% CI: 0.75, 0.91; P < .001) was significantly higher (P = .045) than that for fetal MRI scans obtained after gestational age 26 weeks (AUC, 0.69; 95% CI: 0.57, 0.80; P = .004). Conclusion The hyperintense bronchus sign is a frequently detectable feature at fetal MRI and is associated with airway obstruction particularly before gestational age 26 weeks. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Dubinsky in this issue.

Case Report: Prenatal and Postnatal Management for Fetal Bronchogenic Cysts During the COVID-19 Pandemic

Background: A fetal bronchogenic cyst (BC) is a rare congenital anomaly with an incidence of 0.147-0.238‰. The coronavirus disease 2019 (COVID-19) pandemic, as a particular situation, hindered pregnant women from receiving periodic prenatal checkups. Case Description: Until 34⁺⁶ weeks of gestation, a fetal case of the intrathoracic cyst was found by ultrasound examination. Further, MRI examination confirmed the diagnosis of the congenital mediastinal cystic lesion, probably a BC. Genetic testing was not conducted due to the COVID-19 pandemic. At 38⁺⁵ weeks of gestation with maternal COVID-19 testing negative, a live girl was delivered by cesarean section. Five months later, the child underwent bronchocystectomy, and the postoperative pathological lesions confirmed a (right upper mediastinum) BC. Conclusion: Herein, we reported the prenatal and postnatal management for a rare case of the congenital BC by multidisciplinary approaches during the COVID-19 pandemic. Fetal MRI and screening for fetal chromosomal abnormalities are especially recommended. This case contributes to the awareness that the COVID-19 pandemic interferes with regular follow-up schedules during pregnancy and may interfere with timely performed additional tests; which leads to more accurate genetic counseling. A combination of multidisciplinary approaches, including radiology, infection control, genetic counseling, obstetrics, and pediatric surgery, is pivotal for managing fetal BC during the COVID-19 pandemic.