A novel RYR1 variant in an infant with a unique fetal presentation of central core disease

Ryanodine receptor type 1-related disorder (RYR1-RD) is the most common subgroup of congenital myopathies with a wide phenotypic spectrum ranging from mild hypotonia to lethal fetal akinesia. Genetic testing for myopathies is imperative as the diagnosis informs counseling regarding prognosis and recurrence risk, treatment options, monitoring, and clinical management. However, diagnostic challenges exist as current options are limited to clinical suspicion prompting testing including: single gene sequencing or familial variant testing, multi-gene panels, exome, genome sequencing, and invasive testing including muscle biopsy. The timing of diagnosis is of great importance due to the association of RYR1-RD with malignant hyperthermia (MH). MH is a hypermetabolic crisis that occurs secondary to excessive calcium release in muscles, leading to systemic effects that can progress to shock and death if unrecognized. Given the association of MH with pathogenic variants in RYR1, a diagnosis of RYR1-RD necessitates an awareness of medical team to avoid potentially triggering agents. We describe a case of a unique fetal presentation with bilateral diaphragmatic eventrations who had respiratory failure, dysmorphic facial features, and profound global hypotonia in the neonatal period. The diagnosis was made at several months of age, had direct implications on her clinical care related to anticipated need to long-term ventilator support, and ultimately death secondary an arrhythmia as a result of suspected MH. Our report reinforces the importance of having high suspicion for a genetic syndrome and pursuing early, rapid exome or genome sequencing as first line testing in critically ill neonatal intensive care unit patients and further evaluating the pathogenicity of a variant of uncertain significance in the setting of a myopathic phenotype.

Imaging in the presence of meroanencephaly

Meroanencephaly occurs when there is an incomplete open median calvarial defect. This condition, which is in the spectrum of anencephaly, results in ectopic brain without skin covering and a normal foramen magnum. We present a rare case of a female fetus with meroanencephaly referred to our institution at 24 weeks and imaged with both prenatal ultrasound and MRI, demonstrating an open neural tube defect in the high parietal area and lack of visualization of the supratentorial ventricular system. Postnatal the child survived and went on to require antibiotic therapy and closure of the defect without cerebral spinal fluid diversion but demonstrates severe permanent neurologic deficits.

Fetal and postnatal MRI findings of Blake pouch remnant causing obstructive hydrocephalus

Blake pouch remnant, also known as Blake pouch cyst or persistent Blake pouch, is a posterior fossa embryologic anomaly that is often seen in isolation with most affected patients being asymptomatic. However, even in isolation, Blake pouch remnant can result in obstructive hydrocephalus requiring early neurosurgical intervention making it an important diagnosis for the fetal radiologist to consider. We present a rare case of a patient with prenatally diagnosed "inferior vermian hypoplasia" on fetal MRI that went on to develop progressive obstructive hydrocephalus in infancy secondary to what was determined to be a Blake pouch remnant.

Prenatal diagnosis of Proteus syndrome: Diagnosis of an AKT1 mutation from amniocytes

Proteus syndrome is a mosaic genetic overgrowth disorder caused by a postzygotic, mosaic activating mutation in AKT1. Rare prenatal presentations include segmental tissue overgrowth, and skeletal and CNS anomalies. We present the first report of prenatally diagnosed and molecularly confirmed Proteus syndrome. Prenatal imaging identified megalencephaly, brain and eye malformations, focal soft tissue enlargement, and ambiguous genitalia. Exome sequencing performed on cultured amniocytes demonstrated an AKT1 pathogenic variant consistent with Proteus syndrome, and postnatal examination confirmed the diagnosis. Postnatal Sanger sequencing could not identify the AKT1 pathogenic variant. This case underscores the importance of prenatal exome sequencing on cultured amniocytes for mosaic overgrowth disorders, as well as provides additional information on the prenatal phenotype of Proteus syndrome, and highlights the impact of prenatal diagnosis on postnatal management.

Magnetic resonance imaging of the fetal brain in monochorionic diamniotic twin gestation: correlation of cerebral injury with ultrasound staging and survival outcomes

BACKGROUND

The current staging system of twin-twin transfusion syndrome (TTTS) is based on the ultrasound criteria and does not consider the cerebral injury.

OBJECTIVE

To assess the incidence of cerebral damage on fetal MRI and correlate abnormal cerebral diffusion-weighted imaging (DWI) findings with survival outcome and the ultrasound staging of TTTS.

MATERIALS AND METHODS

We conducted a retrospective review of MRI/DWI of fetal brains and the electronic medical records in monochorionic diamniotic twin gestations. Axial DWI of each fetal brain was performed on 1.5-tesla (T) clinical magnet with b values of 0 s/mm² and 700 s/mm². We correlated MRI/DWI abnormalities with the Quintero staging system and survival outcomes of the fetuses.

RESULTS

Thirty-four pregnancies (68 fetuses) with 42 fetal cerebral abnormalities were identified by MRI/DWI alone. Of these 42 fetal cerebral abnormalities, 33 fetal brain lesions were visible only on DWI (n=25 donor, n=8 recipients; n=30 unilateral, n=3 bilateral; n=26 diffuse, n=7 focal). Quintero staging in these 34 pregnancies was as follows: 9 Stage I, 7 Stage II, 13 Stage III, 4 Stage IV, 1 Stage V. There was no significant correlation between the presence of cerebral infarction or hemorrhage using MRI/DWI and ultrasound staging (P=0.138). The overall survival rate was 63.2% (43/68). There was a significant correlation between the presence of cerebral infarction or hemorrhage on MRI/DWI and delivery status (P=0.009).

CONCLUSION

Abnormal cerebral imaging findings on MRI/DWI from hypoxic-ischemic injury or hemorrhage can be seen at the beginning of the second trimester and do not correlate with the current ultrasound staging system; however, they do correlate with decreased survival. Fetal cerebral abnormalities could be incorporated into the TTTS staging system as an independent risk factor.

Fetal magnetic resonance imaging of skeletal dysplasias

BACKGROUND

Fetal magnetic resonance imaging (MRI) is obtained for prenatal diagnosis and prognostication of skeletal dysplasias; however, related literature is limited.

OBJECTIVE

The purpose of this study was to define the utility of fetal MRI for skeletal dysplasias and to report MRI findings associated with specific diagnoses.

MATERIALS AND METHODS

This retrospective study was approved by the institutional review board; informed consent was waived. Women referred for suspected fetal skeletal dysplasia who underwent MRI between January 2003 and December 2018 were included. Definitive diagnoses were determined by genetic testing, autopsy, physical examination and/or postnatal/postmortem imaging. Fetal MRI examinations and reports were reviewed. Descriptive statistics were used to summarize imaging findings.

RESULTS

Eighty-nine women were referred for fetal MRI for possible skeletal dysplasia. Forty-three (48%) were determined to have a diagnosis other than skeletal dysplasia and nine were excluded for lack of specific skeletal dysplasia diagnosis. Thirty-seven cases of skeletal dysplasia with available fetal MRI and specific diagnosis were included for analysis. Diagnoses included achondrogenesis (n=2), achondroplasia (n=5), Boomerang dysplasia (n=1), campomelic dysplasia (n=2), Jeune syndrome (n=1), Kniest dysplasia (n=1), osteogenesis imperfecta (n=15) and thanatophoric dysplasia (n=10). A specific skeletal dysplasia diagnosis was mentioned in 17/37 (46%) of MRI imaging reports and correct for 14/17 (82%). MRI findings were reported for each specific skeletal dysplasia diagnosis.

CONCLUSION

Fetal MRI is a useful diagnostic tool for skeletal dyplasias and excluded the diagnosis in nearly half of referred pregnancies. In addition to providing fetal lung volumes, fetal MRI demonstrates findings of the brain in achondroplasia and thanatophoric dysplasia, of the spine in achondroplasia and achondrogenesis, of the calvarium in osteogenesis imperfecta and thanatophoric dysplasia, and of the cartilage in Kniest dysplasia.

Prenatal aqueduct stenosis: Association with rhombencephalosynapsis and neonatal outcome

BACKGROUND AND PURPOSE

To examine prenatal MRI and postnatal imaging in fetuses with congenital aqueductal stenosis (CAS) to determine the frequency of association of rhombencephalosynapsis (RES) and how it may affect neonatal intensive care unit (NICU) course.

MATERIALS AND METHODS

A single center IRB-approved retrospective study of children with CAS was performed. Prenatal MRI, postnatal images, and clinical data were reviewed. Statistical analysis was performed with SAS statistical software package version 9.3.

RESULTS

Aqueduct obstruction was confirmed for all 30 participants. Hydrocephalus required shunting in all but one (97%). Fifteen neonates had CAS with rhomboencephalosynapsis (RES) (50%). Although neonatal course between the two groups was comparable, 53% of CAS with RES neonates required feeding assistance versus 20% in CAS only (P = 0.128). Shunting in the CAS with RES group occurred at average of 6 days of life versus CAS group at 55 days (P = 0.196). Biometry measurements showed a statistically significant decrease in pons antero-posterior diameter in both groups (CAS only P = 0.0049 and CAS with RES P = 0.0003) when compared with norms for gestational age.

CONCLUSION

CAS has a high association with RES. Feeding assistance in the NICU and earlier neurosurgical intervention may be required in patients with CAS who also have RES.

Decreased rectal meconium signal on MRI in fetuses with open spinal dysraphism

OBJECTIVE

To evaluate rectal meconium signal in fetuses with open spinal dysraphism and correlate findings with postnatal exam.

METHODS

This is a single-institution Institutional Review Board-approved Health Insurance Portability and Accountability Act (HIPAA) compliant retrospective analysis of fetal MRIs of open spinal dysraphism from 2004 to 2016. Fetuses with diagnostic T1-weighted images and postnatal follow-up at our institution were included.

RESULTS

A total of 115 fetuses (average gestational age 23.9 ± 3.6 weeks) met inclusion criteria. Of these, 80% (92/115) had T1 hyperintense rectal meconium signal. Average height of the meconium column, measured from the base of the bladder to its most inferior extent, was 9.2 ± 4.3 mm in fetuses ≥20-week gestational age and 11.1 ± 4.4 mm in fetuses ≥23-week gestational age (n = 110) . None had bowel dilation. One of 115 fetuses had a simple form of anorectal malformation allowing complete repair in the neonatal period, but this fetus had a normal meconium column height on fetal MRI of 22 mm. The remaining 23/115 fetuses with lack of normal rectal meconium signal were born without evidence of anorectal malformation.

CONCLUSION

Decreased or absent T1-hyperintense rectal meconium signal in fetuses with open spinal dysraphism does not correlate with imperforate anus postnatal and may be a reflection of neurogenic bowel in this patient population.

Congenital aqueduct stenosis: Progressive brain findings in utero to birth in the presence of severe hydrocephalus

PURPOSE

To evaluate the effects of progressive hydrocephalus on the developing brain in a cohort of fetuses diagnosed with congenital aqueduct stenosis by comparing prenatal magnetic resonance imaging and postnatal imaging.

METHODS

This IRB approved single center retrospective review of prenatally diagnosed children with congenital aqueduct stenosis interrogated changes in the brain between prenatal and postnatal imaging and analyzed statistics using SAS software package version 9.3.

RESULTS

Thirty fetuses imaged at a mean gestational age of 26 weeks had aqueduct obstruction confirmed by postnatal imaging. Progressive hydrocephalus required shunting in all but one patient (97%). Those patients with increasing hydrocephalus showed increase in ventricular rupture (60%), loss of septal leaflets (47%), and reduction in white matter and corpus callosum volume (43%). Cerebellar ectopia developed in 27% with 6% meeting the criteria for Chiari I malformation.

CONCLUSION

Hydrocephalus in the fetus results in enlarging ventricular rupture, loss of the septum pellucidum leaflets, volume reduction of brain parenchyma including corpus callosum, and risk for Chiari I anomaly. Given advances in fetal surgery and imaging in the last 3 decades, there may be cause to revisit the idea of in utero cerebral spinal fluid diversion as a means to potentially ameliorate progressive loss of the developing brain.

Fowler syndrome and fetal MRI findings: a genetic disorder mimicking hydranencephaly/hydrocephalus

Fetal ventriculomegaly is a common referral for prenatal MRI, with possible etiologies being hydrocephalus and hydranencephaly. The underlying cause of hydranencephaly is unknown, but many have suggested that the characteristic supratentorial injury is related to idiopathic bilateral occlusions of the internal carotid arteries from an acquired or destructive event. Fowler syndrome is a rare genetic disorder that causes fetal akinesia and a proliferative vasculopathy that can result in an apparent hydranencephaly-hydrocephaly complex. On prenatal imaging, the presence of significant parenchymal loss in the supratentorial and infratentorial brain is a clue to the diagnosis, which should prompt early genetic testing.

Extrafetal Findings on Fetal Magnetic Resonance Imaging: A Pictorial Essay

Although US is the mainstay of fetal imaging, magnetic resonance imaging (MRI) has become an invaluable adjunct in recent years. MRI offers superb soft tissue contrast that allows for detailed evaluation of fetal organs, particularly the brain, which enhances understanding of disease severity. MRI can yield results that are similar to or even better than those of US, particularly in cases of marked oligohydramnios, maternal obesity, or adverse fetal positioning. Incidentally detected extrafetal MRI findings are not uncommon and may affect clinical care. Physicians interpreting fetal MRI studies should be aware of findings occurring outside the fetus, including those structures important for the pregnancy. A systematic approach is necessary in the reading of such studies. This helps to ensure that important findings are not missed, appropriate clinical management is implemented, and unnecessary follow-up examinations are avoided. In this pictorial essay, the most common extrafetal abnormalities are described and illustrated.

Imaging Evaluation of Fetal Megacystis: How Can Magnetic Resonance Imaging Help?

Evaluation of the kidneys, bladder, and amniotic fluid volume forms part of any standard obstetrical ultrasound. When a fetal genitourinary anomaly is suspected, a more detailed evaluation is necessary. This detailed imaging can be challenging in the setting of decreased or absent amniotic fluid or large maternal body habitus, and in complex malformations. In these situations, magnetic resonance imaging can help to better define the fetal anatomy and provide a more confident and specific prenatal diagnosis.

Congenital salivary gland anlage tumor - in utero and postnatal imaging

We present a case of an infant with congenital salivary gland anlage tumor, with fetal and postnatal imaging. To the best of our knowledge, this is the first case describing the in utero imaging findings of salivary gland anlage tumor. A fetal MRI was performed secondary to the clinical finding of polyhydramnios, which identified a nasopharyngeal mass. Because findings were concerning for airway obstruction, the fetus was delivered by ex utero intrapartum treatment (EXIT) to airway procedure. A postnatal CT confirmed the findings of the fetal MRI. The lesion was resected when the baby was 4 days old and recovery was uneventful.

Prenatal Diagnosis of Infantile Myofibroma with Postnatal Imaging Correlation

Infantile myofibroma is the most common fibrous tumor in infancy. A majority of these lesions are solitary and occur in the head and neck region. Unless visceral sites are involved, the clinical course is typically benign. However, the difficulty in these cases is the differentiation of a benign myofibroma from a solitary malignant neoplasm and determination of visceral involvement. Prenatal diagnosis of this condition is rarely described in the literature, but it does indeed have a role in perinatal management. Our patient was initially identified by prenatal ultrasound with fetal MRI for further characterization of the mass. We present the case of a prenatally diagnosed solitary infantile myofibroma of the lower extremity and highlight the role of prenatal imaging in the diagnosis and treatment of this condition.

Congenital peribronchial myofibroblastic tumor: prenatal imaging clues to differentiate from other fetal chest lesions

We present a prenatal case of congenital peribronchial myofibroblastic tumor referred as a congenital pulmonary airway malformation (CPAM) with hydrops and polyhydramnios at 30 weeks' gestational age. US and fetal MRI findings did not fit with the referral diagnosis, raising the possibility of intrinsic lung tumor. Fetal hydrops worsened and the baby was successfully delivered by ex utero intrapartum treatment (EXIT) to resection at 31 weeks' gestational age. To the best of our knowledge, this is a unique case of congenital peribronchial myofibroblastic tumor that underwent comprehensive prenatal evaluation and EXIT procedure with good outcome.

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.

Fetal MRI clues to diagnose cloacal malformations

BACKGROUND

Prenatal US detection of cloacal malformations is challenging and rarely confirms this diagnosis.

OBJECTIVE

To define the prenatal MRI findings in cloacal malformations.

MATERIALS AND METHODS

We performed a retrospective study of patients with cloacal malformations who had pre- and post-natal assessment at our institution. Fetal MRI was obtained in six singleton pregnancies between 26 and 32 weeks of gestation. Imaging analysis was focused on the distal bowel, the urinary system and the genital tract and compared with postnatal clinical, radiological and surgical diagnoses.

RESULTS

The distal bowel was dilated and did not extend below the bladder in five fetuses. They had a long common cloacal channel (3.5-6 cm) and a rectum located over the bladder base. Only one fetus with a posterior cloacal variant had a normal rectum. Three fetuses had increased T2 signal in the bowel and two increased T1/decreased T2 signal bladder content. All had renal anomalies, four had abnormal bladders and two had hydrocolpos.

CONCLUSION

Assessment of the anorectal signal and pelvic anatomy during the third trimester helps to detect cloacal malformations in the fetus. The specificity for this diagnosis was highly increased when bowel fluid or bladder meconium content was identified.

Contribution of magnetic resonance imaging to prenatal differential diagnosis of renal tumors: report of two cases and review of the literature

Enlargement of a kidney on prenatal imaging is usually due to hydronephrosis or cystic renal disease, and much less often results from solid tumors such as mesoblastic nephroma, Wilms' tumor, nephroblastomatosis, renal sarcoma, and angiomyolipoma. All can be diagnosed by ultrasound. Magnetic resonance imaging is useful not only in confirming the presence of a renal mass, but also in the evaluation of the contralateral kidney for subtle abnormalities. We present one case each of Wilms' tumor and mesoblastic nephroma, both detected on antenatal ultrasound and further studied with fetal magnetic resonance imaging.

Brain malformations associated with epignathus: a clue for the correct prenatal diagnosis

We present a case of epignathus (oral teratoma) with midline intracranial associated malformations. This is a rare report of epignathus diagnosed in utero with fetal MRI description of these midline brain malformations, including duplication of the pituitary gland. This case is an example of how these intracranial findings led to the correct diagnosis of a small fetal oral mass.

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.

Acquired renal cysts after pediatric liver transplantation: association with cyclosporine and renal dysfunction

ACKD has been observed in children on dialysis and with chronic renal insufficiency. In one report, ACKD was observed in 30% of pediatric liver transplant recipients after 10 yr. We retrospectively reviewed all renal imaging and measurements of GFR of 235 childhood liver transplant recipients with no known risk for renal cyst formation, no evidence of renal cyst(s) at the time of transplantation and renal imaging at least one yr post-transplant. Twenty-six patients (11%) developed one or more cyst(s). Mean GFR was significantly lower in patients with renal cyst(s). Two (1.4%) of the 146 patients treated with tacrolimus and 24 (27%) of the 89 patients treated with CsA acquired renal cyst(s) (p < 0.001). CsA-treated patients had significantly lower GFR. Multivariate analysis identified CsA as the only independent variable associated with ACKD. These results confirm that ACKD can be a late complication of pediatric liver transplantation. Those at most risk are at least 10-yr post-liver transplantation, have been treated with CsA and have impaired renal function. We speculate that ACKD in these patients is the result of calcineurin inhibitor nephrotoxicity. Whether patients with ACKD will be prone to develop solid renal tumors is unknown.

Water imaging (hydrography) in the fetus: the value of a heavily T2-weighted sequence

BACKGROUND

Since the development of fast imaging sequences, MR has proved to be a helpful tool in the evaluation of fetal pathology. Because of the high water content of fetal tissues and pathology, hydrography imaging (MR fetography) can provide additional diagnostic information.

OBJECTIVE

To demonstrate the benefit of MR fetography in fetal imaging.

MATERIALS AND METHODS

From 2004 to 2005, 126 fetal MR examinations were performed for evaluation of an abnormality depicted on an antenatal sonogram. Single-shot fast spin-echo MR imaging and MR fetography were performed through the area of fetal pathology. The two studies were retrospectively compared.

RESULTS

The primary diagnosis was not changed with the addition of MR fetography. New findings, particularly in the kidneys and spine, were identified in 9% of the patients. When fetal pathology was of high water content (80% patients), the MR fetography imaging increased diagnostic confidence. In 11% of the patients, those with cardiovascular or low water pathology, the MR fetography was not beneficial.

CONCLUSION

The mainstay of fetal imaging is currently the HASTE and SSFSE sequences. However, MR fetography is an excellent adjunct that highlights fetal pathology by reinforcing the diagnosis, identifying additional findings, and providing high-contrast high-resolution images that are helpful when counseling clinicians and patients.

Twin-twin transfusion syndrome: cerebral ischemia is not the only fetal MR imaging finding

BACKGROUND

Twin-twin transfusion syndrome (TTTS) is a complication of monochorionic/diamniotic twin pregnancies. An imbalance of blood flow occurs through placental anastomoses, causing potentially significant morbidity and mortality in both twins. Although the sonographic findings of TTTS are well documented, we believe that MR imaging is a valuable adjunct.

OBJECTIVE

We describe the fetal MR imaging findings associated with TTTS.

MATERIALS AND METHODS

From 2003 to 2005, 37 consecutive MR imaging studies were performed on multiple-gestation pregnancies. Of the 37, 25 were consistent with TTTS, correlated and confirmed by sonographic criteria. MR fetal abnormalities were documented.

RESULTS

Cerebral ischemia, which could not be demonstrated by sonography, was delineated well by MR imaging. New findings noted on fetal MR imaging were enlargement of cerebral venous sinuses in both twins, dilatation of the renal collecting system in the recipient, lung lesions in the recipient and cerebral malformations in the donor.

CONCLUSION

MR imaging is an important adjunct in TTTS imaging. Its benefit over sonography is its clear definition of cerebral pathology, which is important for intervention and counseling. The new findings, particularly in the urinary tract and cerebral venous sinuses, also help support the diagnosis of TTTS and might reveal additional consequences of the altered hemodynamics that occur in TTTS.

Allantoic cyst: a prenatal clue to patent urachus

A patent urachus, which is typically diagnosed as leakage from the umbilicus postnatally, can present as an allantoic cyst in the umbilical cord antenatally. We report a case of a patent urachus with an allantoic cyst diagnosed via fetal MR imaging at 24 weeks' gestation. Early detection allowed for appropriate counseling and prompt corrective surgery after birth.