25 research outputs found

    121. Magnetoresistance of some nickel alloys

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    The Logical Grammatical Structures Test: psychometric properties and normative data in Dutch-speaking children and adolescents

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    Logical grammatical structures comprehension is the ability to understand the relations between objects, actions, and qualities in spoken and written sentences. The Logical Grammatical Structures Test (LGST) was especially devised to assess these abilities in children and adolescents. In the present study the LGST was administered to 405 healthy Dutch children and adolescents. The aims of the present study were (i) to evaluate the psychometric properties of the LGST (using an Item Response Theory framework), and (ii) to establish demographically corrected normative data. The results showed that there was a strong curvilinear relationship between age and LGST performance, i.e., the relative improvement in ability level was much more pronounced for younger children (aged below 14 years) than for older children (aged above 14 years). Level of parental education was positively associated with the LGST performance. Normative data that took the relevant demographic variables into account were established, and it was shown that the LGST had sound psychometric properties. © 2013 Taylor & Francis

    MRI Features for Identifying MYCN-amplified RB1 Wild-type Retinoblastoma.

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    Background MYCN-amplified RB1 wild-type (MYCN <sup>A</sup> RB1 <sup>+/+</sup> ) retinoblastoma is a rare but clinically important subtype of retinoblastoma due to its aggressive character and relative resistance to typical therapeutic approaches. Because biopsy is not indicated in retinoblastoma, specific MRI features might be valuable to identify children with this genetic subtype. Purpose To define the MRI phenotype of MYCN <sup>A</sup> RB1 <sup>+/+</sup> retinoblastoma and evaluate the ability of qualitative MRI features to help identify this specific genetic subtype. Materials and Methods In this retrospective, multicenter, case-control study, MRI scans in children with MYCN <sup>A</sup> RB1 <sup>+/+</sup> retinoblastoma and age-matched children with RB1 <sup>-/-</sup> subtype retinoblastoma were included (case-control ratio, 1:4; scans acquired from June 2001 to February 2021; scans collected from May 2018 to October 2021). Patients with histopathologically confirmed unilateral retinoblastoma, genetic testing (RB1/MYCN status), and MRI scans were included. Associations between radiologist-scored imaging features and diagnosis were assessed with the Fisher exact test or Fisher-Freeman-Halton test, and Bonferroni-corrected P values were calculated. Results A total of 110 patients from 10 retinoblastoma referral centers were included: 22 children with MYCN <sup>A</sup> RB1 <sup>+/+</sup> retinoblastoma and 88 control children with RB1 <sup>-/-</sup> retinoblastoma. Children in the MYCN <sup>A</sup> RB1 <sup>+/+</sup> group had a median age of 7.0 months (IQR, 5.0-9.0 months) (13 boys), while children in the RB1 <sup>-/-</sup> group had a median age of 9.0 months (IQR, 4.6-13.4 months) (46 boys). MYCN <sup>A</sup> RB1 <sup>+/+</sup> retinoblastomas were typically peripherally located (in 10 of 17 children; specificity, 97%; P < .001) and exhibited plaque or pleomorphic shape (in 20 of 22 children; specificity, 51%; P = .011) with irregular margins (in 16 of 22 children; specificity, 70%; P = .008) and extensive retina folding with vitreous enclosure (specificity, 94%; P < .001). MYCN <sup>A</sup> RB1 <sup>+/+</sup> retinoblastomas showed peritumoral hemorrhage (in 17 of 21 children; specificity, 88%; P < .001), subretinal hemorrhage with a fluid-fluid level (in eight of 22 children; specificity, 95%; P = .005), and strong anterior chamber enhancement (in 13 of 21 children; specificity, 80%; P = .008). Conclusion MYCN <sup>A</sup> RB1 <sup>+/+</sup> retinoblastomas show distinct MRI features that could enable early identification of these tumors. This may improve patient selection for tailored treatment in the future. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Rollins in this issue
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