Prenatal diagnosis of intestinal nonrotation using magnetic resonance imaging: Is it possible?

BACKGROUND: Malrotation of the bowel refers to any variation in the rotation and fixation of the gastrointestinal tract during the first trimester and is most commonly detected postnatally. Nonrotation of the bowel and incomplete rotation of the bowel are subtypes of malrotation. OBJECTIVE: To determine if the nonrotation subtype of malrotation of the bowel can be detected on prenatal magnetic resonance imaging (MRI). MATERIALS AND METHODS: Cases from 2012 to 2018 with nonrotation of the bowel without obstruction confirmed by imaging, surgery and/or autopsy were compared to prenatal imaging. Prenatal imaging was retrospectively reviewed to determine if prenatal diagnosis of malrotation could be made. Exclusion criteria included diaphragmatic hernia, omphalocele and gastroschisis. RESULTS: Ten cases of nonrotation diagnosed postnatally by upper gastrointestinal series (upper GI)/small bowel follow-through (SBFT) or autopsy had prenatal MRI. Prenatal MR studies were performed for assessment of heterotaxy syndrome with congenital heart disease (6/10), congenital heart disease with additional anomalies (suspected VACTERL [vertebral, anorectal, cardiac, tracheoesophageal, renal, limb] and suspected lung agenesis, ventriculomegaly) (3/10) and skeletal dysplasia (1/10). Eight upper GI/SBFT cases demonstrated nonrotation of the bowel without obstruction with the small bowel completely on one side of the abdomen contralateral to the stomach and the colon ipsilateral to the stomach; four cases were confirmed by surgery. The small bowel in one upper GI/SBFT case was unilateral contralateral to the stomach with a meandering colon. One case had nonrotation diagnosed at autopsy. There were no cases of postnatal midgut volvulus. Retrospective review of the 10 cases had prenatal MRI performed between 23 and 37 weeks of gestation. The coronal plane was the most optimal plane to assess the position of the stomach, small bowel and colon in relationship to each other. The small bowel was best assessed on T2-weighted images while the colon was best assessed on T1-weighted images. A nonrotated position of the small bowel was present in all 10 fetal MRI cases mirroring postnatal findings, with the small bowel contralateral to the stomach in 9/10 cases and ipsilateral to the stomach (in the right abdomen) in 1/10 cases. The colon was visualized by prenatal MRI in 9/10 cases, with 1 case limited due to a lack of T1-weighted imaging. A nonrotated position of the colon contralateral to the small bowel was present in 7/9 cases. In 2/9 cases, the colon was wandering, positioned on both sides of the midline. Colonic position in all nine cases matched postnatal findings. No cases presented with prenatal bowel obstruction. CONCLUSION: Detection of nonrotation of the bowel is possible on prenatal MRI.

A primer for pediatric radiologists on infection control in an era of COVID-19.

Pediatric radiology departments across the globe face unique challenges in the midst of the current COVID-19 pandemic that have not been addressed in professional guidelines. Providing a safe environment for personnel while continuing to deliver optimal care to patients is feasible when abiding by fundamental recommendations. In this article, we review current infection control practices across the multiple pediatric institutions represented on the Society for Pediatric Radiology (SPR) Quality and Safety committee. We discuss the routes of infectious transmission and appropriate transmission-based precautions, in addition to exploring strategies to optimize personal protective equipment (PPE) supplies. This work serves as a summary of current evidence-based recommendations for infection control, and current best practices specific to pediatric radiologists.

Normal size of the fetal adrenal gland on prenatal magnetic resonance imaging.

BACKGROUND: The adrenal gland plays a vital role in fetal growth. Many disease states such as congenital adrenal hyperplasia, hemorrhage and tumors can lead to morphological changes in the gland. Ultrasound measurements of normal adrenal sizes in the fetus reported in the literature have shown a trend of increasing size with gestational age. There is no literature available on standard fetal adrenal sizes or detailed appearance by fetal MRI. OBJECTIVE: The purpose of this study was to provide MR data on the size and signal characteristics of the fetal adrenal gland throughout the second and third trimesters. MATERIALS AND METHODS: In this retrospective review, we selected 185 prenatal MRIs obtained from Jan. 1, 2014, to May 31, 2017, with normal abdominal findings for inclusion. The adrenal glands were identified in coronal, sagittal or axial T2-W planes and coronal T1-W plane when available. We measured the length and thickness of the medial and lateral limbs of the right and left adrenal glands and recorded signal intensity on T1-W and T2-W sequences, gender and gestational age in each case. RESULTS: The gestational age (GA) ranged 18-37 weeks. Visibility of the adrenal glands on T2-W images was high (90.3-97.2%) up to 30 weeks of GA but declined afterward (47.5-62.2% at 31-37 weeks). Visibility on T1-W images increased with GA, ranging from 21.4% visibility at 18-22 weeks and increasing to 40% at 35-37 weeks. Mean lengths of the adrenal gland limbs steadily increased from 8.2 mm at 18-22 weeks to 11.0 mm at 35-37 weeks. In the second trimester, adrenal glands were low in signal intensity on T2-W images and were surrounded by hyperintense perirenal fatty tissue. In the third trimester, the glands became less distinct, with increasing signal and obliteration of perirenal tissue. The glands were moderately hyperintense on T1-W images throughout pregnancy, with increasing visibility as pregnancy progressed. CONCLUSION: Normal sizes and signal intensities for adrenal glands are reported. Visibility of adrenal glands on T2-W images was 90.3-97.2% up to 30 weeks but declined thereafter. Visibility on T1-W images increased in the third trimester. Adrenal gland sizes increased with gestational age.

Impact of Transcervical Ultrasound for the Diagnosis of Pediatric Peritonsillar Abscesses on Emergency Department Performance Measures.

OBJECTIVES: To evaluate the impact of transcervical ultrasound (US) as the initial imaging study for suspected peritonsillar abscesses (PTAs) on pediatric emergency department (ED) throughput measures. METHODS: A retrospective cohort study of patients evaluated for suspected PTAs between January 2009 and April 2017 was conducted. We compared the ED length of stay (LOS) before and after implementation of transcervical US to diagnose a PTA. The balancing measure was the rate of return visits within 2 weeks. RESULTS: There were 387 eligible patients over the study period. A total of 101 patients were evaluated for PTAs with computed tomography and 286 with US. The mean LOS was significantly less for patients who had US (347 minutes; 95% confidence interval [CI], 330, 364 minutes) compared to computed tomography (426 minutes; 95% CI, 392, 459 minutes), with an absolute difference of 79 minutes (95% CI, 44, 113 minutes). Patients who were evaluated with US did not have an increased rate of return visits (5.9% versus 8.0%; P = .66). CONCLUSIONS: The introduction of transcervical US was associated with a decrease of greater than 1 hour in the ED LOS for patients with suspected PTAs. Given the better radiation profile of US and no increase in the rate of return visits after its implementation, we propose the adoption of a transcervical US-first approach for the diagnosis of PTAs in pediatrics.

Severe nasomaxillary hypoplasia (Binder phenotype) on prenatal US/MRI: an important marker for the prenatal diagnosis of chondrodysplasia punctata.

BACKGROUND: Chondrodysplasia punctata is a skeletal dysplasia caused by a diverse spectrum of etiologies, with outcomes ranging from antenatal demise to a normal life span. Prenatal detection can be challenging. OBJECTIVE: To review a series of cases of chondrodysplasia punctata associated with nasomaxillary hypoplasia, known as the Binder phenotype, and to highlight prenatal ultrasound and MRI findings, as well as postnatal MRI and radiographic findings. MATERIALS AND METHODS: We retrospectively reviewed ultrasound, MRI and radiographic imaging findings in postnatally confirmed cases of chondrodysplasia punctata from 2001 to 2017. We analyzed prenatal findings and correlated them with maternal history, postnatal imaging, phenotype, genetics and outcome. RESULTS: We identified eight cases, all with prenatal US and six of eight with prenatal MRI between 18 weeks and 32 weeks of gestational age. Reasons for referral included midface hypoplasia in four cases; family history in one case; intrauterine growth restriction in one case; short long-bones, intrauterine growth restriction and multicystic kidney in one case; and multiple anomalies in one case. In six cases, postnatal radiographs were performed. In four cases, postnatal spine MRI imaging was performed. The diagnosis of chondrodysplasia punctata was suggested in prenatal reports in six of eight fetuses. Seven of eight fetuses had Binder phenotype with severe nasomaxillary hypoplasia. Limb length was mildly symmetrically short in four of eight cases and normal in four of eight fetuses. Two of eight fetuses had epiphyseal stippling identified prenatally by US; this was present postnatally in six neonates on radiographs. Hand and foot abnormalities of brachytelephalangy were not detected on the prenatal US or MRI but were present in six of eigth fetuses on postnatal radiographs or physical exam. Four of eight fetuses had prenatal spine irregularity on US from subtle stippling. Six of eight had spine stippling on postnatal radiographs. One fetus had cervicothoracic kyphosis on prenatal US and MRI, and this was postnatally present in one additional neonate. One case had prenatally suspected C1 spinal stenosis with possible cord compression, and this was confirmed postnatally by MRI. There was a maternal history of systemic lupus erythematosus in two and hyperemesis gravidarum in one. Outcomes included one termination and seven survivors. CONCLUSION: Chondrodysplasia punctata can be identified prenatally but findings are often subtle. The diagnosis should be considered when a fetus presents with a hypoplastic midface known as the Binder phenotype. Maternal history of lupus, or other autoimmune diseases or hyperemesis gravidarum can help support the diagnosis.

Team counseling in prenatal evaluation: the partnership of the radiologist and genetic counselor.

Fetal medicine programs within children's hospitals have been developed to ensure access to pediatric specialists across multiple disciplines. The cases that present to these programs are usually complex and require involvement of a multidisciplinary care team. Although some providers on the team limit their focus to their pediatric specialty when counseling patients, the radiologist and genetic counselor have a distinct perspective allowing them to take the larger picture into account in the evaluation of the fetus. As first responders, they come together to review images and identify which consultants are most appropriate to counsel the families, and they can help guide patient discussions. In this paper we demonstrate how the combined expertise of the genetic counselor and pediatric radiologist can facilitate more accurate diagnoses and guide the appropriate management of complex fetal anomalies.

Prenatal congenital vertical talus (rocker bottom foot): a marker for multisystem anomalies.

BACKGROUND: Congenital vertical talus is a rare foot anomaly characterized by a prominent calcaneus and rigid forefoot dorsiflexion. While congenital vertical talus has been associated with anomalies such as trisomy 18, myelomeningocele and arthrogryposis, postnatal series have reported cases of isolated congenital vertical talus. OBJECTIVE: The purpose of our study was to determine the incidence of isolated congenital vertical talus prenatally and identify the most common anomalies associated with this finding. MATERIALS AND METHODS: A retrospective review was performed of congenital vertical talus cases identified in our fetal center from 2006 to 2015. The prenatal US and MR imaging appearance of congenital vertical talus was evaluated and differentiation from congenital talipes equinovarus was assessed. Studies were evaluated for additional abnormalities affecting the central nervous system, face, limbs, viscera, growth and amniotic fluid. Imaging findings were recorded and correlated with outcomes when available. RESULTS: Twenty-four cases of congenital vertical talus were identified prenatally (gestational age: 19-36 weeks). All 24 had prenatal US and 21 also underwent fetal MRI on the same day. There were no isolated cases of congenital vertical talus in this series; all 24 had additional anomalies identified prenatally. Sixteen cases had bilateral congenital vertical talus (67%). Additional anomalies were identified in the brain (15), spine (11), face (6), abdominal wall (3), heart (8) and other limbs (12). Chromosomal abnormalities were identified in 6 of 20 patients who underwent genetic testing. Overall, US held some advantage in detecting the abnormality: in 10 cases, US depicted congenital vertical talus more clearly than MRI; in 8 cases, US and MRI were equal in detection and in 3 cases, MRI was superior. In 9/15 cases with intracranial abnormalities, MRI was superior to US in demonstrating structural anomalies. Outcomes included termination (11), intrauterine fetal demise (1), stillbirth or immediate neonatal demise (5), lost to follow-up (1), and 6 survivors with postnatal follow-up. CONCLUSION: In our series, there were no cases of isolated congenital vertical talus, with additional anomalies variably affecting multiple systems including the brain, spine, face, viscera and limbs. When congenital vertical talus is identified prenatally, a thorough search for additional anomalies is indicated. Fetal MRI can be a useful adjunct in confirming the diagnosis and further delineating additional anomalies, particularly in the brain and spine.

Achondroplasia in the Premature Infant: An Elusive Diagnosis in the Neonatal Intensive Care Unit.

Achondroplasia is a difficult prenatal diagnosis to make before the late second and third trimester. We describe two cases where an infant was born prematurely with no overt signs of achondroplasia. Despite multiple chest and abdominal radiographs during the neonatal course, the diagnosis was not made until term equivalent age was reached. We retrospectively reviewed these two cases to highlight the elusive findings of achondroplasia in the premature infant.

Prenatal magnetic resonance and ultrasonographic findings in small-bowel obstruction: imaging clues and postnatal outcomes.

BACKGROUND: Prenatal small-bowel obstruction can result from single or multiple atresias, and it can be an isolated abnormality or part of a syndrome. It is sometimes the first manifestation of cystic fibrosis. Accurate prediction of the level of obstruction and length of bowel affected can be difficult, presenting a challenge for counseling families and planning perinatal management. OBJECTIVE: To review the prenatal US and MRI findings of small-bowel obstruction and to assess whether fetal MRI adds information that could improve prenatal counseling and perinatal management. MATERIALS AND METHODS: We retrospectively reviewed 12 prenatally diagnosed cases of small-bowel obstruction evaluated by both US and MRI from 2005 to 2015. We analyzed gestational age at evaluation, US and MRI findings, gestational age at delivery and postnatal outcomes. RESULTS: The final diagnoses were jejunal atresia (7), ileal atresia (1), cystic fibrosis (3) and combined jejunal and anal atresia (1). Four of the eight with jejunal atresia were found to have multiple small-bowel atresias. Prenatal perforation was noted in three. We identified a trend of increasing complexity of bowel contents corresponding to progressively distal level of obstruction, as indicated by increasing US echogenicity and high T1 signal on MRI. Seven cases of jejunal atresia and one case of ileal atresia demonstrated small ascending, transverse and descending colon (microcolon) with filling of a normal-diameter rectum. In contrast, all three fetuses with cystic fibrosis and the fetus with jejunal-anal atresia demonstrated microcolon as well as abnormal paucity or absence of rectal meconium. Polyhydramnios was present in nine. Eight were delivered prematurely, of whom seven had polyhydramnios. The fetus with jejunal and anal atresia died in utero. Postnatally, three had short gut syndrome, all resulting from multiple jejunal atresias; these three were among a subset of four fetuses whose bowel diameter measured more than 3 cm. Eight infants had no further gastrointestinal complications. The presence of multiple atresias was not predicted by prenatal US or MRI. CONCLUSION: MR provides useful additional information regarding meconium distribution in the small bowel, which helps to clarify the level of obstruction. MR was additionally useful in the assessment of colon and rectal contents, serving as a fetal enema. Abnormally diminished meconium in the rectum suggests cystic fibrosis or combined small-bowel and colonic obstruction, information that is useful in counseling and preparing for postnatal care.

Ultrasound and MR imaging findings in prenatal diagnosis of craniosynostosis syndromes.

BACKGROUND: Craniosynostosis syndromes are uncommonly encountered in the prenatal period. Identification is challenging but important for family counseling and perinatal management. OBJECTIVE: This series examines prenatal findings in craniosynostosis syndromes, comparing the complementary roles of US and MRI and emphasizing clues easily missed in the second trimester. MATERIALS AND METHODS: Six prenatal cases evaluated from 2002 through 2011 were retrospectively reviewed. Referral history, gestational age, and sonographic and MRI findings were reviewed by three pediatric radiologists. Abnormalities of the calvarium, hands, feet, face, airway and central nervous system were compared between modalities. RESULTS: The diagnosis was Apert syndrome in three, Pfeiffer syndrome in two and Carpenter syndrome in one. The gestational age at evaluation ranged from 21 to 33 weeks. All six were evaluated by MRI and US, with two undergoing repeat evaluation in the third trimester, yielding a total of eight MRIs and US exams. The referral history suggested cloverleaf skull in two cases but did not suggest craniosynostosis syndrome in any case. In four, the referral suggested central nervous system (CNS) findings that were not confirmed by MRI; additional CNS findings were discovered in the remaining two. In four cases, developing turricephaly resulted in a characteristic "lampshade" contour of the fetal head. Hypertelorism and proptosis were present in five, with proptosis better appreciated by MRI. Digit abnormalities were present in all, seen equally well by MRI and US. Lung abnormalities in the second trimester in one fetus resolved by the third trimester. CONCLUSION: Prenatal diagnosis of craniosynostosis syndromes is difficult prior to the third trimester. MRI and US have complementary roles in evaluation of these patients.

Congenital lung lesions: prenatal MRI and postnatal findings.

BACKGROUND: Congenital lung lesions refer to a spectrum of malformations and developmental abnormalities of the foregut, pulmonary airways and vasculature. These lesions range from small, asymptomatic to large space-occupying masses that can increase risk of fetal death and respiratory compromise after birth. Prenatal sonography has been used for routine screening in pregnancy. The advent of prenatal magnetic resonance imaging leads to complementary use in the diagnosis of fetal anomalies, including in fetuses with congenital lung lesions. OBJECTIVE: To determine whether fetal MRI can differentiate congenital lung lesions by comparing prenatal diagnosis with postnatal imaging and pathology. MATERIALS AND METHODS: In a 4-year period, 76 fetuses with suspected lung lesions were referred for fetal MRI. We retrospectively reviewed the MR exams and assigned a specific diagnosis based on predetermined criteria. We then compared the prenatal diagnosis to postnatal imaging and pathology. RESULTS: Of 76 cases, 7 were excluded because of an alternative diagnosis. Of the 69 remaining patients, 3 died and 13 were lost to follow-up. Among the 53 patients, there were 56 lung lesions. Four of these lesions were difficult to diagnose because of size and location. Based on imaging records we gave the remaining 52 lesions a specific prenatal diagnosis: 28 congenital pulmonary airway malformations (CPAM), 4 bronchopulmonary sequestrations (BPS), 9 cases of overinflation, 9 hybrid lesions and 2 bronchogenic cysts. The prenatal diagnosis was concordant with postnatal evaluation in 51 of the 52 lung lesions. One fetus given the diagnosis of CPAM prenatally was diagnosed with a hybrid lesion postnatally. CONCLUSION: Prenatal MRI is highly accurate in defining congenital lung anomalies. When fetal MRI findings suggest a specific diagnosis, postnatal findings confirmed the prenatal MRI diagnosis in 98% of cases.

Fetal MRI of cloacal exstrophy.

BACKGROUND: Prenatal ultrasonographic (US) diagnosis of cloacal exstrophy (CE) is challenging. OBJECTIVE: To define the fetal MRI findings in CE. MATERIALS AND METHODS: We performed a retrospective review of eight patients with CE. Imaging was performed between 22 weeks and 36 weeks of gestation with US in four and MRI in eight fetuses. Abdominal wall, gastrointestinal/genitourinary, and spine and limb abnormalities detected were compared with postnatal evaluation. RESULTS: US failed to display CE in one of the four fetuses. Fetal MRI confirmed CE in all eight fetuses by demonstrating absence of a normal bladder and lack of meconium-filled rectum/colon, associated with protuberant pelvic contour and omphalocele. These findings correlated postnatally with CE, atretic hindgut and omphalocele. One fetus had imaging before rupture of the cloacal membrane, showing a protruding pelvic cyst. Absent bladder was noted in the remaining seven fetuses. Confirmed skin-covered spinal defects were noted in seven fetuses, low conus/tethered cord in one and clubfoot in three. Six fetuses had renal anomalies, two had hydrocolpos and one had ambiguous genitalia. CONCLUSION: Fetal MRI provides a confident diagnosis of CE when a normal bladder is not identified, there is a protuberant abdominopelvic contour and there is absence of meconium-filled rectum and colon. Genitourinary and spinal malformations are common associations.

Late gestation fetal magnetic resonance imaging-derived total lung volume predicts postnatal survival and need for extracorporeal membrane oxygenation support in isolated congenital diaphragmatic hernia.

PURPOSE: Magnetic resonance imaging (MRI) has been used as an imaging modality to assess pulmonary hypoplasia in congenital diaphragmatic hernias (CDHs). The objective of this study was to determine if there is a correlation between late gestational fetal MRI-derived total lung volumes (TLVs) and CDH outcomes. METHODS: From 2006 to 2009, 44 patients met criteria of an isolated CDH with a late gestational MRI evaluation. The prenatal TLV (in milliliters) was obtained between 32 and 34 weeks gestation. The measured study outcomes included survival, need for extracorporeal membrane oxygenation (ECMO), and length of stay. RESULTS: There were 39 left and 5 right CDH patients. The average TLV was significantly lower for nonsurvivors (P = .01), and there was a significant association between lower TLV and the need for ECMO (P = .0001). When stratified by TLV, patients with a TLV of greater than 40 mL had a 90% survival vs 35% survival for a TLV of less than 20 mL. Furthermore, patients with a TLV greater than 40 mL had a lower rate of ECMO use (10%) than patients with a TLV of less than 20 mL (86%). Shorter length of stay was found to correlate with increasing TLV (P = .022). CONCLUSION: Late gestation fetal MRI-derived TLV significantly correlates with postnatal survival and need for ECMO. Fetal MRI may be useful for the evaluation of patients who present late in gestation with a CDH.

MRI findings in multifetal pregnancies complicated by twin reversed arterial perfusion sequence (TRAP).

BACKGROUND: Twin reversed arterial perfusion sequence (TRAP) is a rare complication in multifetal monochorionic pregnancies in which a normal "pump" twin provides circulation to an abnormal acardiac co-twin, resulting in high-output cardiac dysfunction in the pump twin. OBJECTIVE: To define fetal MRI findings of TRAP sequence. MATERIALS AND METHODS: Fetal MR images were retrospectively reviewed in 35 pregnancies complicated by TRAP sequence. Abnormalities of the pump twin, acardiac twin, umbilical cord, placenta and amniotic fluid were reviewed. RESULTS: Acardiac twins were classified as: acephalus (51%), anceps (40%), amorphus (9%), acormus (0%). Common findings in acardiac twins include subcutaneous edema (77%), absent cardiac structures (86%), absent or abnormal thoracic cavity (100%), abnormal abdominal organs (100%), superior limbs absent (46%) or abnormal (51%), and inferior limbs present but abnormal (83%). There were pump twin findings of cardiac dysfunction in 43% and intracranial ischemic changes in 3%. Umbilical cord anomalies were present in 97%. CONCLUSION: Acardiac twins present with a predictable pattern of malformation with poorly developed superior structures, more normally formed inferior structures and absent or rudimentary heart. Although usually absent, abnormal heart structures can be seen and do not exclude TRAP sequence. Pump twins are commonly normal with exception of findings of cardiac dysfunction and possible brain ischemia.

Congenital dacryocystocele: prenatal MRI findings.

BACKGROUND: Congenital dacryocystocele can be diagnosed prenatally by imaging. Prenatal MRI is increasingly utilized for fetal diagnosis. OBJECTIVE: To present the radiological and clinical features of seven fetuses with congenital dacryocystocele diagnosed with prenatal MRI. MATERIALS AND METHODS: The institutional database of 1,028 consecutive prenatal MR examinations performed during a period of 4 years was reviewed retrospectively. The cases of congenital dacryocystocele were identified by reading the report of each MRI study. RESULTS: The incidence of dacryocystocele diagnosed with prenatal MRI was 0.7% (n = 7/1,028). The dacryocystocele was bilateral in three fetuses. Mean gestational age at the time of diagnosis was 31 weeks. The indication for prenatal MRI was the presence or the suspicion of central nervous system abnormality in six fetuses and diaphragmatic hernia in one. Dacryocystocele was associated with an intranasal cyst in six of ten eyes. Prenatal sonography revealed dacryocystocele in only two of seven fetuses. Of eight eyes with postnatal follow-up, four did not have any lacrimal symptoms. CONCLUSION: Prenatal MRI can delineate congenital dacryocystocele more clearly and in a more detailed fashion than ultrasonography. Presence of dacryocystocele was symptomatic in only 50% of our patients, supporting that prenatal diagnosis of dacryocystocele might follow a benign course.

Prenatal MRI findings of fetuses with congenital high airway obstruction sequence.

OBJECTIVE: To define the MRI findings of congenital high airway obstruction sequence (CHAOS) in a series of fetuses. MATERIALS AND METHODS: Prenatal fetal MR images were reviewed in seven fetuses with CHAOS at 21 to 27 weeks of gestation. The MRI findings were reviewed. The MRI parameters evaluated included the appearance of the lungs and diaphragm, presence or absence of hydrops, amount of amniotic fluid, airway appearance, predicted level of airway obstruction, and any additional findings or suspected genetic syndromes. RESULTS: All the fetuses viewed (7 of 7) demonstrated the following MRI findings: dilated airway below the level of obstruction, increased lung signal, markedly increased lung volumes with flattened or inverted hemidiaphragms, massive ascites, centrally positioned and compressed heart, as well as placentomegaly. Other frequent findings were anasarca (6 of 7) and polyhydramnios (3 of 7). MRI identified the level of obstruction as laryngeal in five cases and tracheal in two cases. In four of the patients, surgery or autopsy confirmed the MRI predicted level of obstruction. Associated abnormalities were found in 4 of 7 (genetic syndromes in 2). Postnatal radiography (n = 3) showed markedly hyperinflated lungs with inverted or flattened hemidiaphragms, strandy perihilar opacities, pneumothoraces and tracheotomy. Two fetuses were terminated and one fetus demised in utero. Four fetuses were delivered via ex utero intrapartum treatment procedure. CONCLUSION: MRI shows a consistent pattern of abnormalities in fetuses with CHAOS, accurately identifies the level of airway obstruction, and helps differentiate from other lung abnormalities such as bilateral congenital pulmonary airway malformation by demonstrating an abnormally dilated airway distal to the obstruction.