After obtaining familial informed consent, between January 1996 and July 1997, 173 children (5 to 15 years old) with sickle cell disease were enrolled in a prospective multicenter study using blood screening, transcranial Doppler ultrasonography (n = 143), cerebral magnetic resonance imaging (n = 144), and neuropsychologic performance evaluation (n = 156) (Wechsler Intelligence tests WISC-III, WIPPSI-R), which were also performed in 76 sibling controls (5 to 15 years old). Among the 173 patients with sickle cell disease (155 homozygous for hemoglobin SS, 8 sickle cell beta0 thalassemia, 3 sickle cell beta+ thalassemia, 7 sickle cell hemoglobin C disease SC), 12 (6.9%) had a history of overt stroke, and the incidence of abnormal transcranial Doppler ultrasonography (defined as mean middle cerebral artery velocity > 200 cm/sec or absent) was 8.4% in the overall study population and 9.6% in patients with homozygous sickle cell anemia The silent stroke rate was 15%. Significantly impaired cognitive functioning was observed in sickle cell disease patients with a history of stroke (Performance IQ and Full Scale IQ), but also in patients with silent strokes (Similarities, Vocabulary, and Verbal Comprehension). However, infarcts on magnetic resonance imaging were not the only factors of cognitive deficit: Verbal IQ, Performance IQ, and Full Scale IQ were strongly impaired in patients with severe chronic anemia (hematocrit < or = 20%) and in those with thrombocytosis (platelets > 500 x 10(9)/L). Multivariate logistic regression analysis showed that abnormal magnetic resonance imaging (odds ratio [OR] = 2.76) (P = .047), hematocrit < or =20% (OR = 5.85) (P = .005), and platelets > 500 x 10(9)/L (OR = 3.99) (P = .004) were independent factors of cognitive deficiency (Full Scale IQ < 75) in sickle cell disease patients. The unfavorable effect of low hematocrit has already been suggested, but this is the first report concerning an effect of thrombocytosis and showing that silent stroke alone is not a factor of cognitive deficit when not associated with low hematocrit or thrombocytosis. The effect of hydroxyurea, which is known to increase hematocrit and decrease platelet count, on cognitive functioning of sickle cell patients should be evaluated prospectively.

Malformations of cortical development (MCD) include a broad range of disorders that result from disruption of the major steps of cortical development: cell proliferation in germinal zones, neuronal migration and cortical organization. With the improvement and increased utilization of modern imaging techniques, MCD have been increasingly recognized as a major cause of seizure disorders. The advent of Magnetic Resonance Imaging (MRI), in particular, has revolutionized the investigation and the treatment of patients with epilepsy. High-resolution MRI may elucidate the type, the extension and the localization of MCD; therefore, in a group of patients suffering from drugresistant partial epilepsy (DRPE), MRI greatly contributes to the identification of subjects who are suitable for surgical treatment. In the recent past, many efforts were addressed to establish the MRI diagnostic criteria for a peculiar group of MCD, namely focal cortical dysplasias (FCD), histopathologically distinguished as types I and II. Some subtle FCD, which were previously cryptic to imaging investigation, can now be recognized by MRI, however their detection and specification remains challenging. This review will re-visit the neuroimaging findings, including structural MRI, PET, co-registered PET/MRI, MEG and diffusion tensor imaging (DTI) of FCD types I and II. Three major issues will be discussed: 1) the morphological MRI features of the FCDs, 2) the utility of PET and MEG and the use of co-registration methods and 3) diffusion tensor imaging (DTI) as a future modality of investigation, which may add additional informations regarding the microstructure of the grey matter (GM) and white matter (WM) in cortical dysplasia.

SUMMARYPurpose: To evaluate the magnetic resonance imaging (MRI) of pediatric patients with infantile spasms (IS) treated with vigabatrin (VGB) in order to investigate whether VGB affects the brain. Methods: One hundred seven pediatric patients diagnosed with IS and treated with (n = 95) ‡120 mg/kg/day VGB or without (n = 12) VGB were included. MRI and diffusion-weighted imaging (DWI) were retrospectively analyzed. Results: Of the patients who had MRI scans during, but not before, VGB treatment (n = 81), 25 (30.9%) exhibited abnormal MRI signal intensity and/or restricted DWI in the deep gray nuclei and brainstem. Follow-up scans (performed in 15 of the 25 patients) revealed that these changes were reversible upon withdrawal of the medication. Analysis of patients undergoing scans before, during, and after VGB treatment (n = 14) revealed that four patients had abnormal MRI signal during treatment with VBG, two of whom reversed with cessation of VGB, one reversed without cessation of VGB, and another had persistent abnormal signal while being weaned from the VGB. Patients who had not received VGB treatment (n = 12) displayed normal imaging. Younger infants (£12 months) and those with cryptogenic IS were more likely to develop abnormal signal changes on MRI during VGB treatment. Discussion: In pediatric patients, VGB induces reversible MRI signal changes and reversible diffusion restriction in the globi pallidi, thalami, brainstem, and dentate nuclei. The risk for this phenomenon was greater in younger infants and patients with cryptogenic IS.

These deep venous injuries appear to preserve the subplate zone, which is likely to be a significant element to consider in the perspective of the neurodevelopmental outcome.

No abstract

BACKGROUND AND PURPOSE:Epilepsy is considered a disorder of neural networks. The aims of this study were to assess functional connectivity within resting-state networks and functional network connectivity across resting-state networks by use of resting-state fMRI in children with frontal lobe epilepsy and to relate changes in resting-state networks with neuropsychological function.

With use of MEG dipole clusters to localize the epileptogenic zone, diffusion-tensor imaging can help identify alterations in tissue microstructure beyond the MR imaging-visible FCD.

Brain tumors are the most common solid tumors in the pediatric population. Pediatric neuro-oncology has changed tremendously during the past decade owing to ongoing genomic advances. The diagnosis, prognosis, and treatment of pediatric brain tumors are now highly reliant on the genetic profile and histopathologic features of the tumor rather than the histopathologic features alone, which previously were the reference standard. The clinical information expected to be gleaned from radiologic interpretations also has evolved. Imaging is now expected to not only lead to a relevant short differential diagnosis but in certain instances also aid in predicting the specific tumor and subtype and possibly the prognosis. These processes fall under the umbrella of radiogenomics. Therefore, to continue to actively participate in patient care and/or radiogenomic research, it is important that radiologists have a basic understanding of the molecular mechanisms of common pediatric central nervous system tumors. The genetic features of pediatric low-grade gliomas, high-grade gliomas, medulloblastomas, and ependymomas are reviewed; differences between pediatric and adult gliomas are highlighted; and the critical oncogenic pathways of each tumor group are described. The role of the mitogen-activated protein kinase pathway in pediatric low-grade gliomas and of histone mutations as epigenetic regulators in pediatric high-grade gliomas is emphasized. In addition, the oncogenic drivers responsible for medulloblastoma, the classification of ependymomas, and the associated imaging correlations and clinical implications are discussed. © RSNA, 2018 • Abbreviations: CDK = cyclin-dependent kinase, CNS = central nervous system, DIPG = diffuse intrinsic pontine glioma, FGFR1 = fibroblast growth factor receptor 1, GBM = glioblastoma multiforme, HGG = high-grade glioma, IDH = isocitrate dehydrogenase, IDH1 = IDH 1, LGG = low-grade glioma, MAPK = mitogenactivated protein kinase, MEK = MAPK/extracellular signal-regulated kinase (ERK) kinase, PXA = pleomorphic xanthoastrocytoma, SHH = sonic hedgehog, SUFU = suppressor of fused, WHO = World Health Organization, Wnt = wingless RadioGraphics 2018; 38:2102-2122