Navegando por Palavras-chave "Imagem de Tensor de Difusão"

Agora exibindo 1 - 2 de 2
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    Avaliacao do encefalo e medula espinhal de pacientes com neuromielite optica atraves de espectroscopia de protons e tensor de difusao por ressonancia magnetica
    (Universidade Federal de São Paulo (UNIFESP), 2011) Rivero, Rene Leandro Magalhaes [UNIFESP]
    Numa primeira etapa, avaliar pela espectroscopia por RM (MRS) se a substancia branca aparentemente normal dos pacientes com neuromielite optica (NMO) se encontra alterada e analisar se existem diferencas entre os pacientes sem e com lesao na RM encefalica. Numa segunda etapa, avaliar a medula espinhal cervical de pacientes com NMO pelo tensor de difusao (DTI), tanto em areas sem, quanto naquelas com lesao visivel nas imagens ponderadas em T2 e verificar se ha correlacao entre as medidas do DTI e o grau de incapacidade fisica no doente, pesquisando se esta correlacao se preserva ou altera com o tempo de doenca. Metodos: Na primeira etapa, foi realizada a espectroscopia de volume-unico da substancia branca aparentemente normal (SBAN) de 16 pacientes com NMO, comparando os valores das relacoes NAA/Cr, Co/Cr e Ins/Cr, com um grupo controle de individuos saudaveis. Alem disso, verificou-se se havia diferenca na relacao NAA/Cr entre os pacientes com NMO do nosso grupo, em relacao a presenca ou nao de lesoes encefalicas. Na segunda etapa, foi realizado o tensor de difusao (DTI) da medula espinhal cervical de 11 pacientes com NMO, separando por niveis cervicais os locais de alteracao ou nao da medula nas imagens ponderadas em T2. As medidas de DTI destas regioes foram comparadas com a de um grupo controle de individuos saudaveis, em cada nivel. Adicionalmente, avaliou-se se havia correlacao destas medidas com o grau de incapacidade fisica do paciente (EDSS). Resultados: Nao se observou diferenca nas relacoes dos metabolitos entre os pacientes e o grupo controle e tambem a presenca ou nao de lesao encefalica nao alterou a relacao NAA/Cr entre os pacientes com NMO. Na medula espinhal, observou-se alteracao das medidas de DTI nos pacientes com NMO em relacao ao grupo controle, exceto na medida da difusibilidade media (MD) em areas preservadas da medula nas imagens T2. A melhor correlacao entre as medidas de DTI e o EDSS, foi da anisotropia fracionada (FA) em areas de lesao nas imagens em T2. Conclusao: A SBAN dos pacientes com NMO apresentou taxa de metabolitos preservada em relacao ao grupo controle e independente da presenca ou nao de lesoes encefalicas nos pacientes com NMO, reforcando o conceito de que a substancia branca nao e primariamente afetada nesta doenca. Os locais de lesao na medula espinhal nas imagens em T2 sao as areas com maior correlacao com EDSS do paciente, sendo a FA a medida de DTI que apresentou melhor correlacao, que inclusive se manteve com o tempo. Isto tambem reforca a natureza de lesoes mais focais da NMO
  • Imagem de Miniatura
    Item
    Acesso aberto (Open Access)
    Reconhecimento de padrões atencionais e correlatos neurobiológicos em indivíduos com transtorno do déficit de atenção
    (Universidade Federal de São Paulo (UNIFESP), 2015-11-25) Rossi, Adriana Suzart Ungaretti [UNIFESP]; Bueno, Orlando Francisco Amodeo [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Currently it is widely known that diagnostic categories, including ADHD (Attention-Deficit/Hyperactivity Disorder), are quite heterogeneous conditions. In accordance to the Research Domain Criteria approach, the present study aimed to analyze attentional patterns between ADHD of inattentive type and typically development individuals, regrouping the subjects in respect to their attentional performance, regardless of the groups of origin. Possible differences on brain connectivity between the established groups were also explored. A diagnostic traditional analysis comparing ADHD to typically developing individuals was also conducted in order to better delineate the cognitive, behavioral and neurobiological characteristics of the inattentive type. Methods: Recruited participants included 29 ADHD of inattentive type aged 7 to 15 years and 29 typically developed children matched by age, sex and type of school assisted. Latent Class Analysis were applied to reclassify subjects regarding their attentional performance through cognitive (Conners? Continuous Performance Test and digit span backwards) and behavioral measures (Child Behavioral Checklist). Measures of working memory and verbal fluency were also adopted on the categorical analysis. The new classes, as well as diagnostic classes, were compared in respect to white matter measures (fractional anisotropy). Results: Participants were clustered in three new classes regarding their attencional profile. Nonetheless, considering clinical and statistical parameters, analysis were followed selecting a model with two-classes solution: Class 1 - ultra-high risk for attentional problems and Class 2 - normal development of attentional functions. Group comparison in respect to 20 tracts? fractional anisotropy mean values revealed that Class 1 individuals presented increased fractional anisotropy values on left inferior fronto-occipital fasciculus and left inferior longitudinal fasciculus. In what refers to categorical analysis, ADHD individuals, when compared to typically developing ones, revealed higher intraindividual variability, lower processing speed and worse vigilance, selective and sustained attention. When comparison of fractional anisotropy mean values was made between diagnostic categories (ADHD versus typically developing subjects), there were found no evidences of statistically significant differences in respect to the 20 analyzed fiber tracts. Conclusion: The results highlight that even among individuals with same disorder subtype it is possible to identify subsets with more homogeneous neuropsychological profiles, and, subsequently, with underpinning neurobiological differences. It is noteworthy that although the classical categorical approach did not indicate differences in respect to white matter measures between diagnostic groups, when subjects were compared through a more refined analysis - based on dimensions of observable attentional measures - neurobiological differences were found. These data emphasize that specific data-driven clustering allows a better comprehension of some disorders? pathophysiology, what reiterates that brain-behavior relationships may not respect the arbitrary limits imposed by diagnostic classification.