Early cortical folding and the emergence of structural brain asymmetries have been previously analyzed by neuropathology as well as qualitative analysis of magnetic resonance imaging (MRI) of fetuses and preterm neonates. In this study, we present a dedicated image analysis framework and its application for the detection of folding patterns during the critical period for the formation of many primary sulci (20–28 gestational weeks). Using structural information from in utero MRI, we perform morphometric analysis of cortical plate surface development and modeling of early folding in the normal fetal brain. First, we identify regions of the fetal brain surface that undergo significant folding changes during this developmental period and provide precise temporal staging of these changes for each region of interest. Then, we highlight the emergence of interhemispheric structural asymmetries that may be related to future functional specialization of cortical areas. Our findings complement previous descriptions of early sulcogenesis based on neuropathology and qualitative evaluation of 2D in utero MRI by accurate spatial and temporal mapping of the emergence of individual sulci as well as structural brain asymmetries. The study provides the missing starting point for their developmental trajectories and extends our understanding of normal cortical folding.
cortex; development; fetus; folding; lateralization
To describe the association between electrographic seizures and brain injury judged from magnetic resonance imaging (MRI) in newborns treated with hypothermia.
56 newborns treated with hypothermia were monitored using video-EEG through cooling and rewarming, and imaged at a median of 5 days. EEGs were reviewed for seizures and status epilepticus. Moderate-severe injury on MRI was measured using a classification similar to one predicting abnormal outcome in an analogous population.
Seizures were recorded in 17 newborns, five withstatus epilepticus. Moderate-severe injury was more common in newborns with seizures (RR 2.9; 95%CI 1.2-4.5; P=0.02), and present in all with status epilepticus. Children with moderate-severe injury had seizures that were multifocal, later onset, and more likely to have ongoing seizures following 20mg/kg phenobarbital. Newborns with only subclinical seizures were as likely to have injury as compared with those whose seizures had a clinical correlate (57% vs. 60%).
Seizures remain a risk factor for brain injury in the setting of therapeutic hypothermia, especially in neonates with status epilepticus, multifocal onset seizures, and need for multiple medications.However, 40% were spared from brain injury, suggesting that the outcome following seizures is not uniformly poor in children treated with therapeutic hypothermia.
Intensive care; Infant, newborn; Hypothermia, induced; Seizures; Electroencephalography; Magnetic resonance imaging
We examined neonatal predictors of epilepsy in term newborns with neonatal encephalopathy (NE) by studying children enrolled in a longitudinal, single center cohort study. Clinical data were obtained through chart review, and MRI was performed in the neonatal period. We administered a seizure questionnaire to parents of children aged ≥12 months (range 12 months–16.5 years) to determine the outcome of epilepsy. The association between clinical predictors and time to onset of epilepsy was assessed using Cox proportional hazards regression. Thirteen of 129 children developed epilepsy: all had neonatal seizures and brain injury on neonatal MRI. Of the newborns with neonatal seizures, 25% (15.8/1000 person-years) developed epilepsy, with the highest hazard ratios (HR) in the newborns with status epilepticus (HR 35.8, 95% CI 6.5 –196.5). Children with severe or near-total brain injury were more likely to develop epilepsy compared with those with only mild or moderate injury (HR 5.5, 95% CI 1.8–16.8). In a multivariable analysis adjusting for degree of encephalopathy and severe/near total brain injury, status epilepticus was independently associated with epilepsy. These data add to information regarding epilepsy pathogenesis, and further aid clinicians to counsel parents regarding the likelihood that a newborn with NE will develop epilepsy.
Hemimegalencephaly (HMG) is a developmental brain disorder characterized by an enlarged, malformed cerebral hemisphere, typically causing epilepsy that requires surgical resection. We studied resected HMG tissue to test whether the condition might reflect somatic mutations affecting genes critical to brain development. We found that 2/8 HMG samples showed trisomy of chromosome 1q, encompassing many genes, including AKT3, which is known to regulate brain size. A third case showed a known activating mutation in AKT3 (c.49G→A, creating p.E17K) that was not present in the patient’s blood cells. Remarkably, the E17K mutation in AKT3 is exactly paralogous to E17K mutations in AKT1 and AKT2 recently discovered in somatic overgrowth syndromes. We show that AKT3 is the most abundant AKT paralogue in brain during neurogenesis and that phosphorylated AKT is abundant in cortical progenitor cells. Our data suggest that somatic mutations limited to brain could represent an important cause of complex neurogenetic disease.
More than 60 percent of newborns with severe congenital heart disease develop perioperative brain injuries. Known risk factors include: preoperative hypoxemia, cardiopulmonary bypass characteristics, and postoperative hypotension. Infection is an established risk factor for white matter injury in premature newborns. In this study, we examined term infants with congenital heart disease requiring surgical repair to determine whether infection is associated with white matter injury. Acquired infection was specified by site (bloodstream, pneumonia, or surgical site infection) according to strict definitions. Infection was present in 23/127. Pre and post-operative imaging was evaluated for acquired injury by a pediatric neuroradiologist. Overall, there was no difference in newly acquired postoperative white matter injury in infants with infection (30 percent), compared to those without (31 percent). When stratified by anatomy, infants with transposition of the great arteries and bloodstream infection had an estimated doubling of risk of white matter injury that was not significant, whereas those with single ventricle anatomy had no apparent added risk. When considering only infants without stroke, the estimated association was higher, and became significant after adjusting for duration of inotrope therapy. In this study, nosocomial infection was not associated with white matter injury. Nonetheless, when controlling for risk factors, there was an association between bloodstream infection and white matter injury in selected sub-populations. Infection prevention may have the potential to mitigate long-term neurologic impairment as a consequence of white matter injury, which underscores the importance of attention to infection control for these patients.
Heart defects, congenital; Sepsis; Magnetic resonance imaging; Leukomalacia, periventricular; Pneumonia, ventilator acquired
This study reports a large case series of children with Aicardi syndrome. A new severity scoring system is established to assess sidedness of ocular and brain lesions. Thirty-five children were recruited from Aicardi syndrome family conferences. All children received dilated ophthalmologic exams, and brain MRI’s were reviewed. Ocular and brain MRI Aicardi lesion severity scores were devised. A linear mixed model was used to compare each side for the ocular and brain MRI severity scores of Aicardi associated disease. Twenty-six children met inclusion criteria for the study. All subjects were female, ages 3 months to 19 years. Rates per child of optic nerve coloboma, severe lacunae, and microphthalmos in one or both eyes (among those with complete fundus exams available) were 10/24 (42%), 8/22 (36%), and 7/26 (27%), respectively. Ocular and brain MRI asymmetry was found in 18% (4/22) and 58% (15/26) of subjects, respectively, with more right sided brain lesions than left (V=52, P=0.028). A significant correlation between sidedness of brain disease and microphthalmos was seen (T = 2.54, P = 0.02). This study substantiates the range and severity of Aicardi syndrome associated ophthalmologic and brain MRI lesions from prior smaller case series.
The most common cause of arterial ischemic stroke (AIS) in a previously healthy child is a large vessel cerebral arteriopathy. Varicella zoster virus is an established etiology, and recent data implicate a non-specific effect of additional common viral infections on cerebral vessels. The Vascular effects of Infection in Pediatric Stroke (VIPS) study is a multicenter cohort study that will test the hypotheses that (1) infection can lead to childhood AIS by causing vascular injury, and (2) the resultant arteriopathy, and inflammatory markers, predict recurrent stroke.
We are prospectively enrolling 480 children (aged 1 month through 18 years) with AIS and collecting (1) extensive infectious histories (through parental interview), (2) blood and serum samples (and CSF, when clinically obtained), and (3) clinically obtained but standardized brain and cerebrovascular imaging studies. Imaging studies are being centrally reviewed and adjudicated. Centralized laboratory assays will include serologies (acute and convalescent) and molecular assays for herpes viruses, and levels of inflammatory markers. Subjects are followed prospectively for recurrent ischemic events for the duration of the study (minimum of 1 year). We are banking biological specimens (including DNA) for future studies of specific infectious agents and mediators of inflammation relevant to thrombosis and vascular injury.
In a cross-sectional analysis, we will use logistic regression techniques to measure the association between markers of infection (from the clinical history and laboratory assays) and cerebral arteriopathy. In a prospective cohort analysis, we will use survival analysis techniques to determine whether cerebral arteriopathy and inflammatory markers predict recurrent stroke.
VIPS will shed light on the vascular effects of infection in childhood stroke. Because arteriopathy is likely the major predictor of recurrent stroke in children, a better understanding of the vascular injury pathway is critical for the development of rational strategies for secondary stroke prevention in children.
The corpus callosum is hypothesized to play a fundamental role in integrating information and mediating complex behaviors. Here, we demonstrate that lack of normal callosal development can lead to deficits in functional connectivity that are related to impairments in specific cognitive domains. We examined resting-state functional connectivity in individuals with agenesis of the corpus callosum (AgCC) and matched controls using magnetoencephalographic imaging (MEG-I) of coherence in the alpha (8–12 Hz), beta (12–30 Hz) and gamma (30–55 Hz) bands. Global connectivity (GC) was defined as synchronization between a region and the rest of the brain. In AgCC individuals, alpha band GC was significantly reduced in the dorsolateral pre-frontal (DLPFC), posterior parietal (PPC) and parieto-occipital cortices (PO). No significant differences in GC were seen in either the beta or gamma bands. We also explored the hypothesis that, in AgCC, this regional reduction in functional connectivity is explained primarily by a specific reduction in interhemispheric connectivity. However, our data suggest that reduced connectivity in these regions is driven by faulty coupling in both inter- and intrahemispheric connectivity. We also assessed whether the degree of connectivity correlated with behavioral performance, focusing on cognitive measures known to be impaired in AgCC individuals. Neuropsychological measures of verbal processing speed were significantly correlated with resting-state functional connectivity of the left medial and superior temporal lobe in AgCC participants. Connectivity of DLPFC correlated strongly with performance on the Tower of London in the AgCC cohort. These findings indicate that the abnormal callosal development produces salient but selective (alpha band only) resting-state functional connectivity disruptions that correlate with cognitive impairment. Understanding the relationship between impoverished functional connectivity and cognition is a key step in identifying the neural mechanisms of language and executive dysfunction in common neurodevelopmental and psychiatric disorders where disruptions of callosal development are consistently identified.
In the latter half of gestation (20 to 40 gestational weeks), human brain growth accelerates in conjunction with cortical folding and the deceleration of ventricular zone progenitor cell proliferation. These processes are reflected in changes in the volume of respective fetal tissue zones. Thus far, growth trajectories of the fetal tissue zones have been extracted primarily from 2D measurements on histological sections and magnetic resonance imaging (MRI). In this study, the volumes of major fetal zones—cortical plate (CP), subplate and intermediate zone (SP+IZ), germinal matrix (GMAT), deep gray nuclei (DG), and ventricles (VENT)—are calculated from automatic segmentation of motion-corrected, 3D reconstructed MRI. We analyzed 48 T2-weighted MRI scans from 39 normally developing fetuses in utero between 20.57 and 31.14 gestational weeks (GW). The supratentorial volume (STV) increased linearly at a rate of 15.22% per week. The SP+IZ (14.75% per week) and DG (15.56% per week) volumes increased at similar rates. The CP increased at a greater relative rate (18.00% per week), while the VENT (9.18% per week) changed more slowly. Therefore, CP increased as a fraction of STV and the VENT fraction declined. The total GMAT volume slightly increased then decreased after 25 GW. We did not detect volumetric sexual dimorphisms or total hemispheric volume asymmetries, which may emerge later in gestation. Further application of the automated fetal brain segmentation to later gestational ages will bridge the gap between volumetric studies of premature brain development and normal brain development in utero.
brain development; magnetic resonance imaging; growth rate; prenatal; cortex; probabilistic atlas
To establish normative metabolite ratios throughout the newborn brain using 3D MR Spectroscopic Imaging.
Materials and Methods
MRI and MRSI have been valuable tools for assessing normal and abnormal neuronal maturation for newborns. In this study, we performed whole brain 3D MRSI in addition to comprehensive anatomic and other functional imaging methods to examine maturation. 55 newborn subjects (28.4 ± 2.6 weeks post-conceptional age at birth, 34.1 ± 3.1 weeks post-conception age at scan, 32 males and 23 females) had high quality MRSI studies (104 exams) and normal neurodevelopmental outcome (NMS=0, MDI>85) at age 12 months.
The NAA to Cho ratio increased significantly with age for all regions. Lac to NAA ratio decreased significantly with age in the regions of thalamus, basal ganglia, cortical spinal tract, and parietal white matter, and showed a decreasing trend in the other regions.
Brain metabolites can be obtained through in vivo 3D MRSI and used to monitor newborn brain maturation.
newborn; brain; spectroscopy; mrsi
Recently developed techniques for reconstruction of high-resolution 3D images from fetal MR scans allows us to study the morphometry of developing brain tissues in utero. However, existing adult brain analysis methods cannot be directly applied as the anatomy of the fetal brain is significantly different in terms of geometry and tissue morphology. We describe an approach to atlas-based segmentation of the fetal brain with particular focus on the delineation of the germinal matrix, a transient structure related to brain growth. We segment 3D images reconstructed from in utero clinical MR scans and measure volumes of different brain tissue classes for a group of fetal subjects at gestational age 20.5–22.5 weeks. We also include a partial validation of the approach using manual tracing of the germinal matrix at different gestational ages.
Tensor based morphology (TBM) is a powerful approach to analyze local structural changes in brain anatomy. However, conventional scalar TBM methods are unable to present direction-specific analysis of volume changes required to model complex changes such as those during brain growth. In this paper, we describe novel TBM descriptors for studying direction-specific changes in a subject population which can be used in conjunction with scalar TBM to analyze local patterns in directionality of volume change during brain development. We illustrate the use of these methods by studying brain developmental patterns in fetuses. Results show that this approach detects early changes local growth that are related to the early stages of sulcal and gyral formation.
A common solution to clinical MR imaging in the presence of large anatomical motion is to use fast multi-slice 2D studies to reduce slice acquisition time and provide clinically usable slice data. Recently, techniques have been developed which retrospectively correct large scale 3D motion between individual slices allowing the formation of a geometrically correct 3D volume from the multiple slice stacks. One challenge, however, in the final reconstruction process is the possibility of varying intensity bias in the slice data, typically due to the motion of the anatomy relative to imaging coils. As a result, slices which cover the same region of anatomy at different times may exhibit different sensitivity. This bias field inconsistency can induce artifacts in the final 3D reconstruction that can impact both clinical interpretation of key tissue boundaries and the automated analysis of the data. Here we describe a framework to estimate and correct the bias field inconsistency in each slice collectively across all motion corrupted image slices. Experiments using synthetic and clinical data show that the proposed method reduces intensity variability in tissues and improves the distinction between key tissue types.
bias field inhomogeneity; bias field inconsistency; fetal brain; 3D reconstruction; multislice MRI
Modeling and analysis of MR images of the early developing human brain is a challenge because of the transient nature of different tissue classes during brain growth. To address this issue, a statistical model that can capture the spatial variation of structures over time is needed. Here, we present an approach to building a spatio-temporal model of tissue distribution in the developing brain which can incorporate both developed tissues as well as transient tissue classes such as the germinal matrix by using constrained higher order polynomial models. This spatio-temporal model is created from a set of manual segmentations through groupwise registration and voxelwise non-linear modeling of tissue class membership, that allows us to represent the appearance as well as disappearance of the transient brain structures over time. Applying this model to atlas-based segmentation, we generate age-specific tissue probability maps and use them to initialize an EM segmentation of the fetal brain tissues. The approach is evaluated using clinical MR images of young fetuses with gestational ages ranging from 20.57 to 24.71 weeks. Results indicate improvement in performance of atlas-based EM segmentation provided by higher order temporal models that capture the variation of tissue occurrence over time.
Imaging of the human fetus using magnetic resonance (MR) is an essential tool for quantitative studies of normal as well as abnormal brain development in utero. However, because of fundamental differences in tissue types, tissue properties and tissue distribution between the fetal and adult brain, automated tissue segmentation techniques developed for adult brain anatomy are unsuitable for this data. In this paper, we describe methodology for automatic atlas-based segmentation of individual tissue types in motion-corrected 3D volumes reconstructed from clinical MR scans of the fetal brain. To generate anatomically correct automatic segmentations, we create a set of accurate manual delineations and build an in utero 3D statistical atlas of tissue distribution incorporating developing grey and white matter as well as transient tissue types such as the germinal matrix. The probabilistic atlas is associated with an unbiased average shape and intensity template for registration of new subject images to the space of the atlas. Quantitative whole brain 3D validation of tissue labeling performed on a set of 14 fetal MR scans (20.57–22.86 weeks gestational age) demonstrates that this atlas-based EM segmentation approach achieves consistently high DSC performance for the main tissue types in the fetal brain. This work indicates that reliable measures of brain development can be automatically derived from clinical MR imaging and opens up possibility of further 3D volumetric and morphometric studies with multiple fetal subjects.
Malformations of cerebral cortical development include a wide range of developmental disorders that are common causes of neurodevelopmental delay and epilepsy. In addition, study of these disorders contributes greatly to the understanding of normal brain development and its perturbations. The rapid recent evolution of molecular biology, genetics and imaging has resulted in an explosive increase in our knowledge of cerebral cortex development and in the number and types of malformations of cortical development that have been reported. These advances continue to modify our perception of these malformations. This review addresses recent changes in our perception of these disorders and proposes a modified classification based upon updates in our knowledge of cerebral cortical development.
cerebral cortex; malformation of cortical development; microcephaly; cortical dysplasia; polymicrogyria
To hypothesize that detailed examination of early cerebellar volumes over time would distinguish differences in cerebellar growth associated with intraventricular hemorrhage (IVH) and white matter injury (WMI) in preterm infants.
Preterm newborns at the University of California San Francisco (n=57) and the University of British Columbia (n=115) were studied using serial MRI scans near birth and again at near term-equivalent age. Interactive semi-automated tools were used to determine volumes of the cerebellar hemispheres.
Adjusting for supratentorial brain injury, cerebellar hemorrhage, and study site, cerebellar volume increased 1.7cm3/week postmenstrual age (95% CI 1.6–1.7, P<0.001). More severe supratentorial IVH was associated with slower growth of cerebellar volumes (P<0.001). Volumes by 40 weeks were 1.4 cm3 lower in premature infants with grade 1–2 IVH and 5.4 cm3 lower with grade 3–4 IVH. The same magnitude of decrease was found between ipsilateral and contralateral IVH. No association was found with severity of WMI (P=0.3).
Early effects of decreased cerebellar volume associated with supratentorial IVH in either hemisphere may be a result of concurrent cerebellar injury or direct effects of subarachnoid blood on cerebellar development.
preterm; neuroimaging; cerebellum; intraventricular hemorrhage
To compare the association between perinatal events and the pattern and extent of brain injury on early MRI in newborns with and without therapeutic hypothermia for hypoxic-ischemic encephalopathy (HIE).
We performed a cohort study of 35 treated and 25 non-treated neonates who underwent MRI. The injury patterns were defined a priori as: normal (N), watershed (WS) or basal ganglia/thalamus (BG/T) predominant, as well as a dichotomous outcome of moderate-to-severe versus mild-no injury.
Neonates with hypothermia had less extensive WS and BG/T injuries, and a greater proportion had normal imaging. Therapeutic hypothermia was associated with a decreased risk of both BG/T injury (RR 0.29, 95% CI 0.10-0.81, p = 0.01) and moderate-severe injury. Neonates with sentinel events showed a decrease in BG/T predominant injury and increase in normal imaging. All neonates with decreased fetal movements had injury, predominantly WS, regardless of therapeutic hypothermia.
These results validate reports of reduced brain injury following therapeutic hypothermia, and suggest that perinatal factors are important indicators of response to treatment.
Neonatal; MRI; Hypoxia-ischemia; Hypothermia therapy
Defining the structural and functional connectivity of the human brain (the human “connectome”) is a basic challenge in neuroscience. Recently, techniques for noninvasively characterizing structural connectivity networks in the adult brain have been developed using diffusion and high-resolution anatomic MRI. The purpose of this study was to establish a framework for assessing structural connectivity in the newborn brain at any stage of development and to show how network properties can be derived in a clinical cohort of six-month old infants sustaining perinatal hypoxic ischemic encephalopathy (HIE). Two different anatomically unconstrained parcellation schemes were proposed and the resulting network metrics were correlated with neurological outcome at 6 months. Elimination and correction of unreliable data, automated parcellation of the cortical surface, and assembling the large-scale baby connectome allowed an unbiased study of the network properties of the newborn brain using graph theoretic analysis. In the application to infants with HIE, a trend to declining brain network integration and segregation was observed with increasing neuromotor deficit scores.
To investigate the relationship between cerebellar hemorrhage in preterm infants seen on MRI but not ultrasound and neurodevelopmental outcome.
MR images from a cohort study of MRI in preterm newborns were reviewed for cerebellar hemorrhage. Children were assessed at mean 4.8 years with neurological examination and developmental testing using the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-III).
Of 131 preterm newborns, cerebellar hemorrhage was seen on both ultrasound and MRI in 3 newborns; smaller hemorrhages seen only on MRI in 10 (total of incidence of 10%). Adjusting for gestational age at birth, intraventricular hemorrhage, and white matter injury, cerebellar hemorrhage detectable only by MRI was associated with 5.0-fold increased odds of abnormal neurological examination compared with those without hemorrhage (outcome data in 74%). No association was found with scores on WPPSI-III testing.
Cerebellar hemorrhage is not uncommon in preterm newborns. Although associated with neurologic abnormalities, hemorrhage seen only on MRI is associated with much more optimistic outcomes than that visible by ultrasound.
preterm; neuroimaging; neurological outcome; developmental outcomes
Focal cortical dysplasias (FCDs) are localized regions of malformed cerebral cortex and are very frequently associated with epilepsy in both children and adults. A broad spectrum of histopathology has been included in the diagnosis of FCD. Characteristic findings include aberrant radial or tangential lamination of the neocortex (FCD Type I) and cytological abnormalities (FCD Type II). An ILAE task force has re-evaluated available data and proposes a clinico-pathologic classification system of FCDs. The major change since a prior classification represents the introduction of FCD Type III, which occurs in combination with Hippocampal Sclerosis (FCD Type IIIa), or with epilepsy-associated tumors (FCD Type IIIb). FCD Type IIIc is found adjacent to vascular malformations, whereas FCD Type IIId can be diagnosed in association with epileptogenic lesions acquired in early life (i.e., traumatic injury, ischemic injury or encephalitis). Hence, FCD Type I will now refer to isolated lesions, which present either as radial (FCD Type Ia) or tangential (FCD Type Ib) dyslamination of the neocortex, microscopically identified in one or multiple lobes. FCD Type II is an isolated lesion characterized by cortical dyslamination and dysmorphic neurons without (Type IIa) or with balloon cells (Type IIb). Architectural abnormalities adjacent to or within gross malformations of cortical development are frequently observed and not distinguished as a specific FCD variant. This three-tiered classification system will help to better characterize specific clinico-pathological entities and is an important basis to further explore imaging, electro-clinical features, and postsurgical seizure control as well as underlying molecular pathomechanisms.
Epilepsy; Seizures; Hippocampal Sclerosis; Cortical Dysplasia; Neuropathology
Malformations of the midbrain (MB) and hindbrain (HB) have become topics of considerable interest in the neurology and neuroscience literature in recent years. The combined advances of imaging and molecular biology have improved analyses of structures in these areas of the central nervous system, while advances in genetics have made it clear that malformations of these structures are often associated with dysfunction or malformation of other organ systems. This review focuses upon the importance of communication between clinical researchers and basic scientists in the advancement of knowledge of this group of disorders. Disorders of anteroposterior (AP) patterning, cerebellar hypoplasias, disorders associated with defects of the pial limiting membrane (cobblestone cortex), disorders of the Reelin pathway, and disorders of the primary cilium/basal body organelle (molar tooth malformations) are the main focus of the review.
midbrain; hindbrain; cerebellum; malformations
Modeling and analysis of MR images of the developing human brain is a challenge due to rapid changes in brain morphology and morphometry. We present an approach to the construction of a spatiotemporal atlas of the fetal brain with temporal models of MR intensity, tissue probability and shape changes. This spatiotemporal model is created from a set of reconstructed MR images of fetal subjects with different gestational ages. Groupwise registration of manual segmentations and voxelwise nonlinear modeling allow us to capture the appearance, disappearance and spatial variation of brain structures over time. Applying this model to atlas-based segmentation, we generate age-specific MR templates and tissue probability maps and use them to initialize automatic tissue delineation in new MR images. The choice of model parameters and the final performance are evaluated using clinical MR scans of young fetuses with gestational ages ranging from 20.57 to 24.71 weeks. Experimental results indicate that quadratic temporal models can correctly capture growth-related changes in the fetal brain anatomy and provide improvement in accuracy of atlas-based tissue segmentation.
Structural MRI; Fetal imaging; Atlas building; Tissue segmentation
To assess if birth at less than 26 weeks gestation is an important predictor of brain microstructure maturation as determined by using diffusion tensor imaging.
We performed serial MRI and diffusion tensor imaging in 176 infants born at < 33 weeks gestation. Diffusion parameters were calculated for white and gray matter regions. Linear regression for repeated measures was used to assess the effect of extremely premature birth on brain maturation.
In white matter, fractional anisotropy increased by 0.008 per week (95% CI 0.007-0.009, p=<0.0001) and mean diffusivity decreased by 0.021 mm2/sec per week, (95% CI -0.24 to -0.018, p=<0.0001). Birth at < 26 weeks was associated with lower white matter fractional anisotropy (-0.01, 95% CI -0.018 to -0.003, p=0.008) but this effect was eliminated when co-morbid conditions were added to the model. Moderate-severe brain injury was associated with decreased mean white matter fractional anisotropy (-0.012, 95% CI -0.02 to -0.004, p=0.002).
Brain microstructure maturation as measured serially in premature infants is independent of extremely premature birth. Brain injury and co-morbid conditions may be the important determinants of microstructure maturation.
Infant, premature; Magnetic resonance imaging; Diffusion tensor imaging
The natural history of Chiari I malformation in children remains unclear.
In this population-based retrospective cohort study, we searched radiology reports from all head and spine MRI scans (n=5248) performed among 741, 815 children under age 20 within Kaiser Northern California, 1997–1998, for Chiari I. We reviewed medical records and imaging studies to determine clinical and radiographic predictors of significant neurologic symptoms defined as moderate to severe headache, neck pain, vertigo or ataxia.
The 51 patients identified with Chiari I represented 1% of children who had head or spine MRI scans performed during the study period. Headache (55%) and neck pain (12%) were the most common symptoms. Syringomyelia was present in 6 patients (12%) at time of initial diagnosis; no new syrinxes developed during follow-up. Older age at time of diagnosis was associated with increased risk of headache (OR 1.3, 95% CI 1.1–1.5) and significant neurologic symptoms (OR 1.2, 95% CI 1.04–1.4).
Chiari I, an under-recognized cause of headaches in children, is also frequently discovered incidentally in children without symptoms. Larger and longer-term studies are needed to determine the prognosis and optimal treatment of pediatric Chiari I.