MRI morphometry of the neocortex in patients with periventricular nodular heterotopia
Notice bibliographique
Résumé
Background. Human corticogenesis is broadly divided into three phases: proliferation, migration and cortical organization. Accordingly, a defect in any of these phases results in a malformation of cortical development (MCD). By allowing the in vivo visualization of MCDs, magnetic resonance imaging (MRI) has been instrumental in their classification. One such MCD is gray matter heterotopia (GMH), defined as out-of-place masses of gray matter (GM) – termed "nodules" – containing neurons that have failed to migrate to their intended destination. Such nodules have variable presentation in terms of location, lateralization, size and spread in the brain. Three distinct subtypes of GMH have been recognized: periventricular nodular heterotopia (PVNH), subcortical heterotopia, and band heterotopia. The focus of my Master's project is specifically the PVNH subtype of GMH. As all types of GMH, PVNH is highly epileptogenic, and the epilepsy is often drug-resistant. Purpose. To quantify whole-brain changes in cortical thickness and curvature in PVNH, and to assess the spatial relationship between nodules and regions of change.Methods. We obtained T1-weighted (1 x 1 x 1 mm3) images in 41 patients with PVNH and 41 controls on 1.5T- and 3T-scanners. Patients were further divided into unilateral (UL) vs. bilateral (BL) PVNH. Images were registered into stereotaxic space to adjust for differences in brain volume and orientation. We manually mapped the location of nodules, and algorithmically extracted whole-brain neocortical thickness and curvature. We used whole-brain linear modeling to perform group-wise statistics.Results. Nodules were evenly distributed along the ventricles in BL-PVNH, but tended to cluster around the trigone in UL-PVNH. Compared to controls, both UL-PVNH and BL-PVNH patients had increased cortical thickness and curvature in several regions of the brain. Increases in cortical thickness and curvature were found in the same hemisphere as the nodules in UL-PVNH, while in BL-PVNH cortical thickness increases were found bilaterally in the prefrontal cortex, and curvature increases were found bilaterally in the temporal lobe. In both cohorts, morphometric anomalies did not colocalize spatially with the nodules, as assessed by a visual inspection. Significance. The quantitative approach we used here provides precise measurements of cortical thickness and curvature in PVNH, as opposed to qualitative and subjective visual descriptions. The hemispheric colocalization finding makes it more likely that both the heterotopic nodules and the cortical thickening are the results of the same disrupted developmental mechanism. Conversely, the absence of a spatial relationship between heterotopic nodules and morphometric anomalies suggests differential cellular signaling and migration pathways.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».