Antenatal MR Research Articles

Post-mortem Characterisation of a Case With an ACTG1 Variant, Agenesis of the Corpus Callosum and Neuronal Heterotopia.

Cytoplasmic Actin Gamma 1 (ACTG1) gene variant are autosomal dominant and can cause CNS anomalies (Baraitser Winter Malformation Syndrome; BWMS). ACTG1 anomalies in offspring include agenesis of the corpus callosum (ACC) and neuronal heterotopia which are ectopic nodules of nerve cells that failed to migrate appropriately. Subcortical and periventricular neuronal heterotopia have been described previously in association with ACC. In this case report, we investigated a neonatal brain with an ACTG1 gene variant and a phenotype of ACC, and neuronal heterotopia (ACC-H) which was diagnosed on antenatal MR imaging and was consistent with band heterotopia seen on post-mortem brain images. Histologically clusters of neurons were seen in both the subcortical and periventricular white matter (PVWM) brain region that coincided with impaired abnormalities in glial formation. Immunohistochemistry was performed on paraffin-embedded brain tissue blocks from this case with ACTG1 variant and an age-matched control. Using tissue sections from the frontal lobe, we examined the distribution of neuronal cells (HuC/HuD, calretinin, and parvalbumin), growth cone (drebrin), and synaptic proteins (synaptophysin and SNAP-25). Additionally, we investigated how the ACTG1 variant altered astroglia (nestin, GFAP, vimentin); oligodendroglia (OLIG2) and microglia (Iba-1) in the corpus callosum, cortex, caudal ganglionic eminence, and PVWM. As predicted in the ACTG1 variant case, we found a lack of midline radial glia and glutamatergic fibers. We also found disturbances in the cortical region, in glial cells and a lack of extracellular matrix components in the ACTG1 variant. The caudal ganglionic eminence and the PVWM regions in the ACTG1 variant lacked several cellular components that were identified in a control case. Within the neuronal heterotopia, we found evidence of glutamatergic and GABAergic neurons with apparent synaptic connections. The data presented from this case study with BWMS with variants in the ACTG1 gene provides insight as to the composition of neuronal heterotopia, and how disturbances of important migratory signals may dramatically affect ongoing brain development.

MRI evaluation of the placenta from normal variants to abnormalities of implantation and malignancies.

Even though the placenta has been known for millennia, it is still considered one of the most complex and least understood human organs. Imaging of the placenta is gaining attention due to its impact on fetal and maternal outcomes. MRI plays a vital role in evaluation of inconclusive cases by ultrasonography. It enables precise mapping of placental abnormalities for proper multidisciplinary planning and management. In this article we provide a comprehensive in-depth review of the role of antenatal MR in evaluating "The Placenta." We will describe the protocols and techniques used for MRI of the placenta, review anatomy of the placenta, describe MRI features of major placental abnormalities including those related to position, depth of implantation, hemorrhage, gestational trophoblastic neoplasia, and retained products of conception and discuss the added value of MRI in the management and preoperative planning of such abnormalities. Level of Evidence: 3 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2019;50:1702-1717.

Editorial

In the last decade there have been significant improvements in all the fields of management of patients with spinal dysraphism, which have increased dramatically the quality of life of these children. Prevention of spina bifida with food fortification is becoming increasingly practiced worldwide. As result, in many parts of the world the frequency of myelomeningocele has decreased. Intrauterine closure of myelomeningocele has been attempted in many institutions with variable results. While it is still at the sphere of experimental therapy, it is reasonable to anticipate progress in this field in the next decade. Antenatal MR imaging is already providing very high level of detail even before the child is born. This creates new ethical dilemmas and requires additional care, but has improved significantly the overall management of patients and their families. Further improvements are anticipated in this field. Management of neuropathic bladder has improved significantly in the last decade and is anticipated to play an increasing role in the long term follow up. Surgery for spinal cord tethering in all its forms has improved in the last decade, with far more chances of complete untethering now in comparison to 10-15 years ago, with the use of micro-neurosurgical techniques and intraoperative monitoring. It is reasonable to expect that in the next decade, intraoperative neurophysiological monitoring during spinal cord surgery will become mandatory. In the 2013 Annual Special Issue we have assembled a team of authors distinguished in their fields, who bring us up to date with all the latest developments.

Prenatal diagnosis of OEIS (omphalocele, bladder exstrophy, imperforate anus, clubfeet) variant associated with increased nuchal translucency and OEIS complex with ambiguous genitalia associated with corrected transposition of the great arteries: case series and review of the literature

The OEIS complex refers to a combination of defects consisting in omphalocele, bladder exstrophy, imperforate anus and spinal defects and represents a rare nosologic entity (from 1:200,000 to 1:400,000 pregnancies). The defect probably occurs in early blastogenesis or in mesodermal migration during the primitive streak period. Two cases of OEIS complex diagnosed prenatally by ultrasound are reported. The medical record regarding differential diagnosis, associated anomalies, treatment and prognosis has also been sought and reported. Differential diagnosis with exstrophy-epispadias complex and/or cloacalexstrophy complex may be difficult antenatally by means of ultrasound. However, color Doppler has been proved to aid the diagnosis of bladder exstrophy by depicting the urine flow in direct communication with the abdominal cavity and has been useful in showing the course of the perivesical umbilical arteries. Prenatal 3D ultrasound with tomographic ultrasound imaging (TUI) and antenatal MR imaging might be useful adjuncts to conventional 2D scan in aiding the prenatal diagnosis of such malformation.

Antenatal ultrasound and MRI findings of Pena–Shokeir syndrome

Pena-Shokeir syndrome is an autosomal recessive disorder characterized by arthrogryposis, facial anomalies (micrognathia), camptodactyly, polyhydramnios and lung hypoplasia. We report prenatal ultrasonographic, antenatal MR and postnatal examination findings of a fetus with Pena-Shokeir syndrome. Pena-Shokeir syndrome is a potentially lethal condition and most cases are diagnosed prenatally by ultrasound. Fetal MR can be performed to look associated neurological malformation.

Alteration of Human Fetal Subplate Layer and Intermediate Zone During Normal Development on MR and Diffusion Tensor Imaging

The subplate layer and intermediate zone are the precursors for neonatal white matter. The aims of this study were to evaluate 1) T1 and T2 signal intensity, and 2) FA of subplate and intermediate zone in postmortem fetuses and correlate with histology, and 3) T2 signal intensity of subplate and intermediate zone on antenatal MR imaging. Fourteen immersion-fixed normal brains from 18 to 25 gestational weeks underwent 1.5T MR imaging, including DTI and histologic examination. The subplate and intermediate zone were graded on a scale of 1-5 on T1 and T2, and FAs were evaluated and then correlated with age. Seventeen antenatal MR images from 20 to 26 gestational weeks with normal brain were evaluated by using the same grading. On T1 postmortem MR imaging, subplate has lower signal intensity compared with intermediate zone; subplate signal intensity correlated positively (r = 0.66, P = .012) with age, and intermediate zone signal intensity correlated negatively (r = -0.78, P = .001) with age. On T2 postmortem MR imaging, subplate has higher signal intensity compared with intermediate zone and remained persistently high in signal intensity; intermediate zone signal intensity showed moderate correlation (r = 0.48, P = .086) with age. FA of subplate correlated positively (r = 0.55, P < .001) with age; FA of intermediate zone correlated negatively (r = -0.64, P < .0001) with age. On histology, extracellular matrix decreased and cellularity increased in subplate layer, tangentially organized cellularity decreased, and projecting fibers became thicker in intermediate zone with increasing gestation. The findings on T2-weighted antenatal MR imaging were similar to T2-weighted postmortem MR imaging. The changes in signal intensity and FA of subplate and intermediate zone in the second trimester reflect microstructural changes on histology.

Antenatal MR imaging of pulmonary lymphangiectasia secondary to hypoplastic left heart syndrome

We report a case of pulmonary lymphangiectasia detected antenatally with MRI in a fetus with hypoplastic left heart syndrome and a restrictive atrial septum.

Comparison of prenatal and postnatal MRI findings in the evaluation of intrauterine CNS anomalies requiring postnatal neurosurgical treatment

To assess the diagnostic capability of fetal magnetic resonance imaging (MRI) in children suspected antenatally to harbor central nervous system (CNS) defects that require immediate postnatal neurosurgical treatment. Between 2003 and 2005, 13 fetal MRI scans were performed in mothers suspected to have fetuses with congenital CNS defects that would require surgery soon after birth. Comparisons between antenatal and postnatal scans were made with emphasis on diagnostic accuracy of antenatal examinations. All mothers were scanned using heavily T2-weighted fat-saturated sequences, allowing rapid acquisitions to avoid movement artefacts. Imaging quality was satisfactory in all patients. Diagnoses made antenatally were: myelomeningocele in seven, meningocele in one, diastematomyelia in one, occipital meningocele in one, and isolated hydrocephalus in three children. Of the seven children with antenatal diagnosis of myelomeningocele, one proved to have spinal lipoma postnatally. The patient who antenatally was diagnosed with meningocele proved to have spinal lipoma postnatally. These two were early antenatal MR scans. Antenatal diagnosis of hydrocephalus was made in five of the six confirmed myelomeningocele patients, which was verified postnatally. Antenatal diagnosis of Chiari II malformation was made in all six confirmed myelomeningocele patients. The antenatal diagnoses of occipital meningo-encephalocele and isolated hydrocephalus were verified postnatally. Antenatal diagnosis of diastematomyelia was not verified postnatally. Fetal MRI scanning is an effective, noninvasive method of assessing in-utero CNS abnormalities. The diagnostic accuracy has improved to allow prediction of clinical outcome and counseling for possible treatment, but is not perfect yet to allow counseling for termination of pregnancy.

Meconium pseudocyst secondary to ileal atresia complicated by volvulus: antenatal MR demonstration

We report a case of meconium pseudocyst evaluated by prenatal MR imaging. The unusual features were its huge size, the absence of meconium peritonitis, and its development late in fetal life. The case also demonstrates a possible diagnostic pitfall since it suggests that rapid deterioration of a mechanically compensated bowel obstruction may occur, potentially occurring only after an MRI study has been performed.

Antenatal MR diagnosis of urinary hydrometrocolpos due to urogenital sinus

Hydrometrocolpos is cystic dilatation of the vagina and uterus due to congenital vaginal obstruction. It may be secretory or urinary in character and manifests in the neonatal period with abdominal distension. Urinary hydrometrocolpos occurs in patients with urogenital sinus or cloacal anomaly. A rare case of antenatal MR diagnosis of urinary hydrometrocolpos due to urogenital sinus is presented.

OC166: Imaging and histopathological features of fetal cortical malformations

(7 cleft lip or cleft lip and palate, 2 cyst of oral cavity), chest (3 right diaphragmatic hernia, 1 sequestration, 3 displaced heart, 1 thymic hyperplasia, 1 axillary lymphangioma), urinary system (1 duplex kidney), abdomen (4 bowel dilatation, an intra-hepatic artero-venous fistula, a pelvic cyst, 1 ascites and bowel calcifications), were represented. Results: In 27 of 32 cases with CNS anomalies, US and MR provided diagnostic images of similar and adequate quality. In the 5 remaining cases US performed better. The antenatal diagnosis was however confirmed after birth in all cases. Among the fetuses with extraCNS anomalies, either antenatal MR or postnatal findings were consistent with sonographic diagnosis in 22 out of 26 cases. A discordance between MR and US was noted in 3 cases. In two fetuses with sonographic diagnosis of cleft lip an unsuspected cleft palate was revealed at MR and confirmed after birth. In a fetus with right deviation of the heart and normally placed stomach, intrathoracic bowel loops were detected at MR and diaphragmatic hernia was documented after birth. The antenatal diagnosis was not confirmed after birth in one case of meconium peritonitis, an abdominal teratoma was diagnosed postnatally. Conclusions: In our own experience, ultrasound and MR performed similarly in CNS anomalies, and ultrasound provided in general better results in early gestation. It is of note that MR was superior in the specific diagnosis and surgical staging of cranial clefts.