Fetal Intraventricular Hemorrhage in Open Neural Tube Defects: Prenatal Imaging Evaluation and Perinatal Outcomes.

BACKGROUND AND PURPOSE: Fetal imaging is crucial in the evaluation of open neural tube defects. The identification of intraventricular hemorrhage prenatally has unclear clinical implications. We aimed to explore fetal imaging findings in open neural tube defects and evaluate associations between intraventricular hemorrhage with prenatal and postnatal hindbrain herniation, postnatal intraventricular hemorrhage, and ventricular shunt placement. MATERIALS AND METHODS: After institutional review board approval, open neural tube defect cases evaluated by prenatal sonography between January 1, 2013 and April 24, 2018 were enrolled (n = 504). The presence of intraventricular hemorrhage and gray matter heterotopia by both prenatal sonography and MR imaging studies was used for classification. Cases of intraventricular hemorrhage had intraventricular hemorrhage without gray matter heterotopia (n = 33) and controls had neither intraventricular hemorrhage nor gray matter heterotopia (n = 229). A total of 135 subjects with findings of gray matter heterotopia were excluded. Outcomes were compared with regression analyses. RESULTS: Prenatal and postnatal hindbrain herniation and postnatal intraventricular hemorrhage were more frequent in cases of prenatal intraventricular hemorrhage compared with controls (97% versus 79%, 50% versus 25%, and 63% versus 12%, respectively). Increased third ventricular diameter, specifically >1 mm, predicted hindbrain herniation (OR = 3.7 [95% CI, 1.5-11]) independent of lateral ventricular size and prenatal intraventricular hemorrhage. Fetal closure (n = 86) was independently protective against postnatal hindbrain herniation (OR = 0.04 [95% CI, 0.01-0.15]) and postnatal intraventricular hemorrhage (OR = 0.2 [95% CI, 0.02-0.98]). Prenatal intraventricular hemorrhage was not associated with ventricular shunt placement. CONCLUSIONS: Intraventricular hemorrhage is relatively common in the prenatal evaluation of open neural tube defects. Hindbrain herniation is more common in cases of intraventricular hemorrhage, but in association with increased third ventricular size. Fetal closure reverses hindbrain herniation and decreases the rate of intraventricular hemorrhage postnatally, regardless of the presence of prenatal intraventricular hemorrhage.

Correlation of prenatal and postnatal MRI findings in schizencephaly.

BACKGROUND AND PURPOSE: Schizencephaly is a rare malformation of the brain characterized by a gray matter-lined defect extending from the pial surface to the lateral ventricles. The purpose of this study was to correlate imaging findings of schizencephaly and associated anomalies on fetal and postnatal MR imaging and assess possible changes that may occur from the prenatal-to-postnatal state. MATERIALS AND METHODS: A retrospective review of subjects with schizencephaly who had both pre- and postnatal MR imaging was performed. Subject age, cleft type, number, location, and features of the defects and associated anomalies were recorded. Normalized dimensions of the defect and ipsilateral ventricle were measured and correlated to changes in the clefts between pre- and postnatal imaging. RESULTS: Ten subjects with 18 clefts (8 bilateral) were included. Most defects (83%) were open on prenatal MR imaging, but 47% of those were found to have subsequently closed on postnatal imaging. Evidence of prior hemorrhage was seen in 83%. Prenatal MR imaging detected all cases of an absent septum pellucidum but detected a fraction of gross polymicrogyria and missed all cases of optic nerve hypoplasia. The normalized ipsilateral ventricular and inner and middle width dimensions of the defects were significantly decreased at postnatal imaging (P < .05). The widths of the defects, ventricular width, and presence of hemorrhage were not predictors of closure of prenatally diagnosed open defects (P > .05). CONCLUSIONS: In our series, nearly half of prenatally open schizencephaly defects had closed on postnatal imaging. Prenatal MR imaging was only able to demonstrate some of the associated anomalies.

CT and MRI of pediatric skull lesions with fluid-fluid levels.

Fluid-fluid levels can occur whenever different fluid densities are contained within a cystic or compartmentalized lesion, usually related to the evolution of hematoma or necrosis. Review of the literature demonstrated that throughout the skeletal system, the most common etiology for fluid-fluid levels is aneurysmal bone cyst, but there are no dedicated studies of the pediatric calvaria, to our knowledge. In this report, we present clinicopathologic characteristics and CT and MR imaging of 11 patients with pediatric skull mass lesions demonstrating fluid-fluid levels. MR imaging demonstrated more fluid-fluid levels compared with CT in all cases. The etiologies of skull lesions with fluid-fluid levels were Langerhans cell histiocytosis in 4 (36.6%), aneurysmal bone cysts in 3 (27.2%), cephalohematoma in 3 (27.2%), and metastatic neuroblastoma in 1 (9%). Radiologists should be aware of the other etiologies of calvarial lesions with fluid-fluid levels in the pediatric skull.

Non-accidental brain trauma in infants: diffusion imaging, contributions to understanding the injury process.

Analysis of MRI diffusion images from 33 infants suffering from non-accidental trauma reveals five patterns of injury. These are diffuse supratentorial hypoxic ischemic, watershed hypoxic ischemic, venous infarction, diffuse axonal injury and contusion.

3T magnetic resonance arteriography in pediatric cerebrovascular disease.

Based on a series of 20 cases, eight with 1.5T and 3T MRA's, 3T MRA provides improvement over 1.5T MRA in imaging the vessels of the circle of Willis in pediatric patients with vascular disease. Dephasing artifact is reduced and laminal stenosis or occlusions become better depicted.

Acute diffusion abnormalities in the hippocampus of children with new-onset seizures: the development of mesial temporal sclerosis.

We studied the role of early diffusion-weighted imaging DWI in the investigation of children with new-onset prolonged seizures which eventually result in unilateral hippocampal sclerosis (HS). We carried out MRI on five children aged 17 months to 7 years including conventional and diffusion-weighted sequences. We calculated apparent diffusion coefficients (ADC) for the affected and the normal opposite hippocampus. Follow-up examinations were performed, including DWI and ADC measurements in four. We studied four children within 3 days of the onset of prolonged psychomotor seizures and showed increased signal on T2-weighted images, and DWI, indicating restricted diffusion, throughout the affected hippocampus. The ADC were reduced by a mean of 14.4% in the head and by 15% in the body of the hippocampus. In one child examined 15 days after the onset of seizures, the ADC were the same on both sides. All five patients showed hippocampal atrophy on follow-up 2-18 months later. In the four patients in whom ADC were obtained on follow-up, they were increased by 19% in the head and 17% in the body. DWI may represent a useful adjunct to conventional MRI for identifying acute injury to the hippocampus which results in sclerosis.

Magnetic resonance imaging of carotid artery abnormalities in patients with sphenoid sinusitis.

Sphenoid sinusitis is unusual in children, but when it occurs, it can lead to serious intracranial complications. We show the value of MRI in demonstrating intracranial abnormalities due to sphenoid sinus infection, particularly those involving the internal carotid arteries and cavernous sinuses. We reviewed our imaging experience of sphenoid sinusitis and found four patients with ICA narrowing who had undergone MR evaluation including conventional and diffusion imaging. MR angiography was also performed in three patients to determine the extent of ICA narrowing. Narrowing of ICA was found in the cavernous segment in all patients and in the supraclinoid segment in three. Cerebral infarction was found in two patients. In one patient the cavernous sinus showed hyperintensity on diffusion-weighted images and hypointensity on apparent diffusion coefficient map, suggesting reduced diffusion. Although infrequent in children, sphenoid sinus infection should be considered as a possible cause of intracranial infection, particularly in teenagers. Early recognition of cavernous sinus involvement and ICA narrowing may lead to prompt treatment and hence a more favorable outcome.

Diffusion-weighted imaging in acute bacterial meningitis in infancy.

Bacterial meningitis is frequently fatal or leads to severe neurological impairment. Complications such as vasculitis, resulting in infarcts, should be anticipated and dealt with promptly. Our aim was to demonstrate the complications of meningitis by diffusion weighted imaging (DWI) in patients who deteriorated despite therapy. We studied 13 infants between the ages of 1 day and 32 months who presented with symptoms ranging from fever and vomiting to seizures, encephalopathy and coma due to bacterial meningitis, performing MRI, including DWI, 2-5 days after presentation. Multiple infarcts were found on DWI in 12 of the 13, most commonly in the frontal lobes (in 10). Global involvement was seen in four children, three of whom died; the fourth had a very poor outcome. In one case abnormalities on DWI were due to subdural empyemas. We diagnosed vasculitis in three of five patients studied with MRA. We think DWI an important part of an MRI study in infants with meningitis. Small cortical or deep white-matter infarcts due to septic vasculitis can lead to tissue damage not easily recognized on routine imaging and DWI can be used to confirm that extra-axial collections represent empyemas.

Diffusion-weighted imaging in the evaluation of watershed hypoxic-ischemic brain injury in pediatric patients.

The purpose of our study was to determine the usefulness of echo-planar diffusion-weighted imaging (EPDI) in the evaluation of watershed hypoxic-ischemic brain injury in pediatric patients. Eighteen patients ranging in age from 3 weeks to 12 years were evaluated for evidence of ischemic/infarction changes on conventional MR and EPDI. Included in the study group were five patients with sickle cell disease, four with congenital heart disease, four with hypotensive episodes with various etiologies, three with sepsis, and two with encephalitis or meningitis. Patients were examined 2 h to 6 days after the initial insult, with follow-up studies in four patients at 1 to 62 days after the initial examination. After conventional MR imaging (T1, FSE T2, and FLAIR), diffusion-weighted MR imaging was performed using high-speed, single-shot EP techniques with TR 6000, TE 144, matrix 96 x 128, FOV 23.3 x 31 and five b values of 0, 160, 360, 640, and 1,000 s/mm2. EPDI demonstrated abnormally increased signal in watershed ischemic/infarction zones in all initial cases. Apparent diffusion coefficients (ADC) were obtained in 59 lesions. When compared with radiographically normal (on EPDI) contralateral brain parenchyma, 45 demonstrated a relatively decreased ADC, while eight had normal ( +/- 10%) and six had increased ADC. In four cases, signal abnormalities on EPDI were not seen or exceeded that seen with conventional MR imaging. In the remaining cases, signal abnormalities were obvious on EPDI and more subtle on conventional MR imaging. Follow-up studies demonstrated resolution of abnormal EPDI signal with persistent abnormalities on conventional imaging in some cases, while others revealed an increase in size or number of EPDI signal abnormalities, suggesting ongoing acute ischemic/infarctive changes. EPDI is a rapid, sensitive technique for detecting watershed ischemic/infarction changes in pediatric patients with hypoperfusion episodes, at times before such changes are apparent on conventional MR images and/or are clinically apparent.

Diffusion-weighted imaging and fluid attenuated inversion recovery imaging in the evaluation of primitive neuroectodermal tumors.

The aim of our study was to determine whether fluid-attenuated inversion recovery (FLAIR) imaging and diffusion-weighted imaging (DWI) would be helpful in characterizing primitive neuroectodermal tumors (PNET) from other pediatric brain tumors. We expected that the compact cellular nature and the relatively small extracellular space of this tumor would affect the signal intensity on both pulse sequences relative to the more sparsely cellular glial tumors that have larger extracellular spaces. Eighteen pediatric patients with PNET were examined on a 1.5 T MRI with routine imaging plus FLAIR and compared with 28 patients with nonPNET. DWI was also performed in 7 PNET and 18 non-PNET. Seventyeight percent of PNET were isointense to gray matter on FLAIR while 82% of non-PNET were hyperintense and only one was isointense (3%). Diffusion was abnormally restricted in all 7 PNET examined (100%) but was restricted in non-PNET in only 1 out of 18 (6%) patients who had DWI. The differences in the histologic architecture between PNET and non-PNET are reflected in both FLAIR imaging and in DWI.

Diffusion imaging in pediatric central nervous system infections.

Our purpose was to investigate the role of diffusion imaging (DI) in central nervous system (CNS) infections in pediatric patients. It was anticipated that DI would be more sensitive than conventional MRI in the detection of the infarctive complications of infection, and possibly, in the detection of the infectious process as well. Seventeen pediatric patients, eight having meningitis,, five with herpes encephalitis, three with brain abscess or cerebritis and one with sepsis, were evaluated at 1.5-T with DI. All herpes patients had positive DI at the site of herpetic involvement, and two had the addition of watershed infarctions. DI demonstrated more lesions in three of the four cases of herpetic encephalitis. Half the meningitis cases had watershed infarction where DI was better and half had vasculitic infarctions in which DI was equal to or better than conventional MRI. Diffusion imaging was more sensitive than conventional MRI alone in detection of changes due to infections and ischemic lesions, but did not differentiate between them by DI or apparent diffusion coefficient (ADC), although anatomic distribution of lesions proved useful.

Ultrafast MR imaging of the normal posterior fossa in fetuses.

OBJECTIVE: The purpose of our study was to determine if a standard imaging protocol using ultrafast MR sequences could adequately reveal normal posterior fossa anatomy in fetuses and, if so, to document a template on MR imaging for normal posterior fossa development. MATERIALS AND METHODS: A retrospective review found 66 MR imaging studies of 63 fetuses, 16-39 weeks' gestation age (mean, 25 weeks' gestation), who were referred between June 1996 and May 1999 for evaluation of non-central nervous system anomalies revealed on prenatal sonography. All fetuses had normal brains and spines on prenatal sonography. The standard MR imaging protocol included axial, sagittal, and coronal half-Fourier acquisition single-shot turbo spin echo (HASTE); sagittal and coronal two-dimensional fast low-angle shot (FLASH); and axial turbo T1-weighted FLASH images through the fetal brain. Structures that we analyzed were the fourth ventricle, the cisterna magna, the vermis, the cerebellar hemispheres, and the brainstem. Using the HASTE sequences, we documented gestational age-specific signal intensity changes in the cerebellar hemispheres and the brainstem. RESULTS: The posterior fossa anatomy was sufficiently well defined to exclude abnormalities of the fourth ventricle and cerebellar vermis in all cases. Because of high T2-weighting, good contrast enhancement, and good signal-to-noise ratios, HASTE images provided the best anatomic definition of the posterior fossa. CONCLUSION: Normal posterior fossa anatomy can be adequately shown on ultrafast MR images, which can be helpful when prenatal sonography is equivocal.

Improvement in hindbrain herniation demonstrated by serial fetal magnetic resonance imaging following fetal surgery for myelomeningocele.

CONTEXT: Hindbrain herniation occurs in a large percentage of children with myelomeningocele and is the leading cause of death in this population. The effect of early fetal closure of myelomeningocele on hindbrain herniation is unknown. OBJECTIVE: To determine whether early fetal closure of myelomeningocele affects hindbrain herniation. DESIGN: Case series of patients undergoing fetal myelomeningocele closure with serial measurements of hindbrain herniation and a mean follow-up of 182 days. SETTING: Tertiary care medical center. PARTICIPANTS: Ten patients undergoing fetal myelomeningocele closure at 22 to 25 weeks' gestation between March 1998 and February 1999. MAIN OUTCOME MEASURES: Need for shunt placement; degree of hindbrain herniation (grades 0-3) found on magnetic resonance imaging (MRI) performed prior to surgery and 3 and 6 weeks after fetal surgery, as well as shortly after birth; gestational age at delivery. RESULTS: All initial fetal MRI scans performed at 19 to 24 weeks' gestation showed significant (grade 3) cerebellar herniation and absence of spinal fluid spaces around the cerebellum. Six fetuses were delivered electively at 36 weeks' gestation after lung maturity was established. The other 4 were delivered prematurely, at 25, 30, 30, and 31 weeks of gestation, and the 25-week gestation neonate died. All 9 surviving neonates showed improvement in the hindbrain hernia at the 3-week postoperative fetal scan (grade 2, n = 4; grade 1, n = 5). On the postnatal scan, all patients showed grade 1 hindbrain herniation. Only 1 patient required placement of a ventriculoperitoneal shunt. CONCLUSION: In this series of patients, fetal myelomeningocele closure resulted in improvement in hindbrain herniation as demonstrated by serial MRI scans.

Development of the paranasal sinuses in children with sinus disease.

In a previous report, the authors defined the normal development of the paranasal sinuses. Landmarks and dimensions relevant to functional endoscopic sinus surgery were measured on the computed-tomography images of 145 children who were free of significant sinusitis. The present study compares those normal values to the same measurements in 235 cases of sinus disease. No significant difference was found between normal and diseased groups in any of the 10 dimensions originally reported or in six derived measures. There appears to be no association between sinus disease and any of these dimensions. The previously reported norms are applicable to cases of pediatric sinus disease.

Orbital vascular lesions. Role of imaging.

Vascular lesions represent an important subgroup of orbital abnormalities; however, there is much controversy regarding their pathophysiology and nomenclature. Attempts at resolution of some of the issues have resulted in changes of names of some of the lesions (e.g., lymphangioma to venolymphatic malformation). Imaging plays an important role in delineation and characterization of these lesions. A radiologist informed about the pathophysiology and attentive to the internal architecture of the lesions shown on images, particularly MR images, often can predict the histologic diagnosis. Imaging information helps clarify some of the controversies surrounding these lesions.

Changes in brain water diffusion during childhood.

We studied the changes in brain water diffusion in childhood as seen on diffusion-weighted MRI in 30 children from 1 day of life to 17 years to provide a data base and to investigate the correlation of diffusion changes with known patterns of white matter maturation. The apparent diffusion coefficient (ADC) and apparent anisotropy (AA) were calculated in numerous regions of the brain to include major white matter tracts and gray matter. ADC and AA values were directly related to the structural maturity and compactness of the white matter tracts and changed with aging in a way that predated early myelination markers such as signal change on T1- or T2-weighted images. Diffusion of water is sensitive to structural changes in the brain such as white matter maturation and may be useful in investigating white matter disorders.

Advances in pediatric neuroimaging.

Magnetic resonance evaluation of the pediatric central nervous system is rapidly improving in a number of ways: (1) anatomically with higher resolution; (2) with greater sensitivity to pathological processes characterized by increased water content utilizing fluid attenuated inversion recovery imaging (FLAIR); (3) with greater speed of acquisition with ultrafast (1 s/image) and echo planar imaging techniques (50 ms/image); (4) with measurement of cerebral blood flow as perfusion; (5) with measurement of water proton dispersion (e.g. diffusion imaging); (6) with measurement of biochemical components within tissues with proton spectroscopy; and (7) with evaluation of cortical activation with functional magnetic resonance imaging.

MRI in the assessment of the supportive soft tissues of the cervical spine in acute trauma in children.

We carried out a retrospective analysis of imaging and clinical findings in 52 children with a history of cervical spinal trauma. No patient had evidence of a fracture on plain films or CT. All had MRI at 1.5 T because of persistent or delayed symptoms, unexplained findings of injury or instability, or as further assessment of the extent of soft-tissue injury. Clinical follow-up ranged from 6 months to 3.5 years. MRI was evaluated for its influence on therapy and outcome. MRI was positive in 16 (31%) of 52 patients. Posterior soft-tissue or ligamentous injury was the most common finding in the 10 patients with mild to moderate trauma, while acute disc bulges and longitudinal ligament disruption, each seen in one case, were uncommon. MRI was superior to CT for assessment of the extent of soft-tissue injury and for identification of spinal cord injuries and intracanalicular hemorrhage in the six patients with more severe trauma. MRI specifically influenced the management of all four patients requiring surgery by extending the level of posterior stabilization. No patients with normal MRI or any of the 10 with radiographically stable soft-tissue injury on MRI, developed delayed clinical or radiographic evidence of instability or deformity.

1H MR spectroscopy of the basal ganglia in childhood: a semiquantitative analysis.

Proton MR spectra of the basal ganglia were obtained from 28 patients, 24 male and 14 female, median age 16.3 months (5 weeks to 31 years). They included 17 patients with normal MRI of the basal ganglia without metabolic disturbance (control group) and 11 patients with various metabolic diseases: one case each of high serum sodium and high serum osmolarity, cobalamin C deficiency, Leigh disease, Galloway-Mowat syndrome, Pelizaeus-Merzbacher disease, hemolytic-uremic syndrome and Wilson disease and two cases of Alagille syndrome and methylmalonic acidemia with abnormal MRI of the basal ganglia or blood or urine analysis (abnormal group). The MR spectrum was measured by using STEAM. The MR-visible water content of the region of interest was obtained. Levels of myoinositol, choline, creatine and N-acetylaspartate were measured using a semiquantitative approach, with absolute reference calibration. In the control group, there was a gradual drop of water content over the first year of life; N-acetylaspartate, creatine and myoinositol levels showed no significant change with age, in contrast to the occipital, parietal and cerebellar regions. Choline showed a gradual decrease for the first 2 years of life and then remained fairly constant. In the abnormal group the water content was not significantly different. N-Acetylaspartate was decreased in patients with high serum sodium and high serum osmolarity, cobalamin C deficiency, Leigh disease and one case of methylmalonic acidemia. Decreased creatine was also found in Leigh disease, and decreased choline in Galloway-Mowat syndrome and Wilson disease. Myoinositol was elevated in the patient with abnormally high serum sodium, and decreased in the hemolytic-uremic syndrome.