Usha D. Nagaraj

Impaired Global and Regional Cerebral Perfusion in Newborns with Complex Congenital Heart Disease

OBJECTIVE To compare global and regional cerebral perfusion in newborns with congenital heart disease (CHD) and healthy controls using arterial spin labeling (ASL) magnetic resonance imaging (MRI) prior to open heart surgery. STUDY DESIGN We performed brain MRIs in 101 newborns (58 controls, 43 CHD) using 3-dimensional fast spin echo pseudo-continuous ASL. Cerebral blood flow (CBF) ASL images were linearly coregistered to T2-weighted images for anatomic delineation and selection of regions-of-interest. Anatomic regions included frontal white matter (FWM), occipital white matter (OWM), thalami, and basal ganglia (BG). RESULTS Newborns with single ventricle CHD demonstrated significantly lower global (P = .044) and regional BG (P = .025) CBF compared with controls. Mean regional CBF in the thalami in cyanotic newborns with CHD was lower compared with controls (P = .004). Mean regional CBF in thalami (P = .02), BG (P = .01), and OWM (P = .03) among newborns with cyanotic CHD was lower than those with acyanotic CHD. Newborns with CHD ventilated prior to MRI had increased global (P = .016) and OWM (P = .013) CBF compared with those not ventilated. CONCLUSIONS Newborns with uncorrected cyanotic or single ventricle CHD show disturbances in cerebral perfusion compared to healthy controls using ASL. Cardiac physiology and preoperative hemodynamic compromise play an important role in preoperative alterations in global and regional cerebral perfusion. Our data suggest that ASL may be useful for studying cerebral perfusion in newborns at high risk for cerebral ischemia, such as those with complex CHD.

Neuroimaging features of Cornelia de Lange syndrome.

BackgroundCornelia de Lange syndrome is a rare genetic disease characterized by distinctive facial dysmorphia and dwarfism. Multiple organ system involvement is typical. Various central nervous system (CNS) aberrations have been described in the pathology literature; however, the spectrum of neuroimaging manifestations is less well documented.ObjectiveTo present neuroimaging findings from a series of eight patients with Cornelia de Lange syndrome.Materials and methodsThe CT/MR database at a single academic children’s hospital was searched for the terms “Cornelia,” “Brachmann” and “de Lange.” The search yielded 18 exams from 16 patients. Two non-CNS and six exams without available images were excluded. Ten exams from eight patients were evaluated by a board-certified neuroradiologist.ResultsAll patients had skull base dysplasia, most with an unusual coronal basioccipital cleft (7/8). All brain MR exams showed microcephaly, volume loss and gyral simplification (5/5). Six patients had an absent massa intermedia. Four patients had small globe anterior segments; three had optic pathway hypoplasia. Basilar artery fenestration was present in two patients; vertebrobasilar hypoplasia was present in one patient. The inner ear vestibules were dysplastic in two patients. One patient had pachymeningeal thickening. Spinal anomalies included scoliosis, segmentation anomalies, endplate irregularities, basilar invagination, foramen magnum stenosis and tethered spinal cord.ConclusionTypical imaging manifestations of Cornelia de Lange syndrome include skull base dysplasia with coronal clival cleft, cerebral and brainstem volume loss, and gyral simplification. Membranous labyrinth dysplasia, anterior segment and optic pathway hypoplasia, basilar artery fenestration, absent massa intermedia and spinal anomalies may also be present.

Prenatal evaluation of atelencephaly

Atelencephaly is a rare lethal congenital brain malformation characterized by underdevelopment of the prosencephalon and is often accompanied by the facial features seen in some cases of holoprosencephaly, such as cyclopia. We report a case of atelencephaly in the fetus with characteristic ultrasound findings. In addition, we report the findings on fetal MRI, which have not been previously described in the literature.

Hindbrain Herniation in Chiari II Malformation on Fetal and Postnatal MRI

The authors examined the neuroimaging findings with a focus on hindbrain herniation and ventricular size in fetuses with open spinal dysraphism and compared them with postnatal imaging features in groups undergoing prenatal-versus-postnatal repair. Thirty-two of 102 (31.3%) fetuses underwent in utero repair of open spinal dysraphism; 68.6% (70/102) underwent postnatal repair. Of those who underwent prenatal repair 81.3% (26/32) had resolved cerebellar ectopia postnatally. Of those who had severe cerebellar ectopia (grade 3) that underwent postnatal repair, 65.5% (36/55) remained grade 3, while 34.5% (19/55) improved to grade 2. They conclude that most fetuses who undergo in utero repair have resolved cerebellar ectopia postnatally. BACKGROUND AND PURPOSE: As the practice of in utero repair of myelomeningoceles becomes more prevalent, knowledge of the expected MR imaging findings has become increasingly important. Our aim was to examine neuroimaging findings with a focus on hindbrain herniation and ventricular size in fetuses with open spinal dysraphism and to compare them with postnatal imaging features in groups undergoing prenatal-versus-postnatal repair. MATERIALS AND METHODS: Single-center retrospective analysis was performed on MRIs of fetuses with open spinal dysraphism from January 2004 through July 2015 with available postnatal imaging. One hundred two fetuses were included. Reports from available fetal ultrasound were also examined. Images were reviewed by 2 board-certified fellowship-trained pediatric neuroradiologists. Descriptive analyses were performed to demonstrate the distribution of the imaging findings. RESULTS: Thirty-two of 102 (31.3%) fetuses underwent in utero repair of open spinal dysraphism; 68.6% (70/102) underwent postnatal repair. Ninety-four of 102 (92.2%) fetuses had cerebellar ectopia. Of those who underwent prenatal repair (26 grade 3, 6 grade 2), 81.3% (26/32) had resolved cerebellar ectopia postnatally. Of those who had severe cerebellar ectopia (grade 3) that underwent postnatal repair, 65.5% (36/55) remained grade 3, while the remaining 34.5% (19/55) improved to grade 2. The degree of postnatal lateral ventriculomegaly in those that underwent prenatal repair (20.3 ± 5.6 mm) was not significantly different from that in those that underwent postnatal repair (21.5 ± 10.2 mm, P = .53). Increased Chiari grade was significantly correlated with decreased head size for gestational age on fetal sonography (P = .0054). CONCLUSIONS: In fetuses with open spinal dysraphism and severe Chiari II malformation that do not undergo prenatal repair, most have no change in the severity of cerebellar ectopia/Chiari grade. However, in fetuses that undergo in utero repair, most have resolved cerebellar ectopia postnatally.

Differentiating Closed Versus Open Spinal Dysraphisms on Fetal MRI

OBJECTIVE The purpose of this study is to identify differences in findings between open and closed spinal dysraphisms seen on fetal MR images. MATERIALS AND METHODS A single-institution retrospective analysis of fetal MR images for spinal dysraphism was performed. Postnatal images and clinical and operative reports were reviewed. RESULTS Sixteen fetuses with postnatally confirmed closed spinal dysraphisms were included. Of these, 25% (4/16) had posterior fossa anomalies, 12.5% (2/16) had ventriculomegaly, and 37.5% (6/16) had OEIS (omphalocele, exstrophy, imperforate anus, and spinal defects) complex. Of 90 fetuses with postnatally confirmed open spinal dysraphism, 95.6% (86/90) had posterior fossa anomalies, 85.6% (77/90) had ventriculomegaly, and none had OEIS complex. Twenty fetuses with open spinal dysraphism were randomly selected to compare with fetuses with closed spinal dysraphisms. Continuity of the epidermal and subcutaneous tissues with the sac wall on fetal MR images was seen in 93.8% (15/16) of patients with closed spinal dysraphisms, as opposed to 5% (1/20) of patients with open spinal dysraphisms. The mean (± SD) sac wall thickness was less in open (0.7 ± 0.6 mm) than closed (2.9 ± 1.3 mm; p < 0.001) spinal dysraphism. None of the fetuses had T1-hyperintense fat within the defect. CONCLUSION On fetal MR images, closed spinal dysraphisms tend to have a sac wall in continuity with the epidermal and subcutaneous tissues, a thicker sac wall, fewer posterior fossa anomalies, and high association with OEIS complex.

Evaluation of Subependymal Gray Matter Heterotopias on Fetal MRI

BACKGROUND AND PURPOSE: Subependymal grey matter heterotopias are seen in a high proportion of children with Chiari II malformation and are potentially clinically relevant. However, despite its growing use, there is little in the literature describing its detection on fetal MRI. Our aim was to evaluate the accuracy in diagnosing subependymal gray matter heterotopias in fetuses with spinal dysraphism on fetal MR imaging. MATERIALS AND METHODS: This study is a retrospective analysis of 203 fetal MRIs performed at a single institution for spinal dysraphism during a 10-year period. Corresponding obstetric sonography, postnatal imaging, and clinical/operative reports were reviewed. RESULTS: Of the fetal MRIs reviewed, 95 fetuses were included in our analysis; 23.2% (22/95) were suspected of having subependymal gray matter heterotopias on fetal MR imaging prospectively. However, only 50% (11/22) of these cases were confirmed on postnatal brain MR imaging. On postnatal brain MR imaging, 28.4% (27/95) demonstrated imaging findings consistent with subependymal gray matter heterotopia. Only 40.7% (11/27) of these cases were prospectively diagnosed on fetal MR imaging. CONCLUSIONS: Fetal MR imaging is limited in its ability to identify subependymal gray matter heterotopias in fetuses with spinal dysraphism. It is believed that this limitation relates to a combination of factors, including artifacts from fetal motion, the very small size of fetal neuroanatomy, differences in imaging techniques, and, possibly, irregularity related to denudation of the ependyma/subependyma in the presence of spinal dysraphism and/or stretching of the germinal matrix in ventriculomegaly.

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

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

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.

Outcome of Isolated Absent Septum Pellucidum Diagnosed by Fetal Magnetic Resonance Imaging (MRI) Scan

Improved fetal imaging has resulted in increased diagnosis of isolated absent septum pellucidum without other intracranial abnormalities. There is little literature regarding outcomes for these fetuses. This study hypothesized the majority of infants diagnosed by fetal magnetic resonance imaging (MRI) with isolated absent septum pellucidum would retain this diagnosis postnatally. Specifically, in the absence of postnatal endocrine or ophthalmologic abnormalities, postnatal imaging would find no additional related findings, and fetuses would be at low risk for developmental delay. Two of 8 subjects met postnatal criteria for septo-optic dysplasia; remaining subjects had normal postnatal endocrine and ophthalmologic evaluations and no significant related findings on postnatal MRI. One subject without septo-optic dysplasia had delays on developmental screening; all others had normal screening (range of follow-up 8-72 months). Our study questions the necessity of postnatal imaging for prenatally diagnosed isolated absent septum pellucidum. Majority of fetuses with isolated absent septum pellucidum retained this diagnosis postnatally.

Spinal Imaging Findings of Open Spinal Dysraphisms on Fetal and Postnatal MRI

BACKGROUND AND PURPOSE: Fetal MRI has become a valuable tool in the evaluation of open spinal dysraphisms making studies comparing prenatal and postnatal MRI findings increasingly important. Our aim was to determine the accuracy of predicting the level of the spinal dysraphic defect of open spinal dysraphisms on fetal MR imaging and to report additional findings observed when comparing fetal and postnatal MR imaging of the spine in this population. MATERIALS AND METHODS: A single-center retrospective analysis was performed of fetal MRIs with open spinal dysraphisms from 2004 through 2016 with available diagnostic postnatal spine MR imaging. Images were reviewed by 2 board-certified fellowship-trained pediatric neuroradiologists. Corresponding clinical/operative reports were reviewed. RESULTS: One hundred nineteen fetal MRIs of open spinal dysraphisms were included. The level of the osseous defect between fetal and postnatal MR imaging was concordant in 42.9% (51/119) of cases and was 1 level different in 39% (47/119) of cases. On postnatal MR imaging, type II split cord malformation was seen in 8.4% (10/119) of cases, with only 50% (5/10) of these cases identified prospectively on fetal MR imaging. Syrinx was noted in 3% (4/119) of prenatal studies, all cervical, all confirmed on postnatal MR imaging. CONCLUSIONS: Fetal MR imaging is accurate in detecting the level of the spinal dysraphic defect, which has an impact on prenatal counseling, neurologic outcomes, and eligibility for fetal surgery. In addition, fetal MR imaging is limited in its ability to detect split cord malformations in patients with open spinal dysraphisms. Although rare, fetal MR imaging has a high specificity for detection of cervical spinal cord syrinx.