Imagem de tensor de difusão na epilesia de lobo temporal mesial
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2016-02-26
Autores
Sanches, Patrícia [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Objetivo: Epilepsia de lobo temporal mesial (ELTM) é a epilepsia refratária mais comum do adulto. A esclerose hipocampal (EH) é a alteração estrutural mais frequentemente relacionada a esta doença. Técnicas quantitativas de análise de difusão permitem a análise mesoscópica in vivo da fisiopatologia das epilepsias. O objetivo deste estudo foi analisar a variação dos principais parâmetros de difusão e explorar as diferenças entre duas metodologias de análise voxel à voxel de imagens comparando um grupo de pacientes com ELTM com controles. Métodos: Foram selecionados pacientes com diagnóstico de ELTM. Os pacientes e um grupo controle foram submetidos a ressonância magnética de 3 Tesla. Os parâmetros de difusão foram obtidos das imagens. Com base nos tensores, um template customizado foi criado e as imagens registradas em um espaço padrão. Três formas de comparação de cada parâmetro foram realizadas: morfometria baseada em voxel (VBM), estatística espacial baseada em tratos (TBSS) e analise especifica de tratos. Resultados: Foram investigados 24 pacientes com ELTM e 36 controles. 10 apresentaram EH à esquerda, 11 à direita e três bilateral com predomínio à esquerda. Nos pacientes, o VBM mostrou as maiores alterações localizadas no giro parahipocampal direito (aumento de difusão axial, radial e média; volumes de 290, 758 e 595 mm3; p = 0,001, < 0,0001 e < 0,0001 respectivamente) e no lobo temporal esquerdo (redução de anisotropia fracionada; 719 mm3; p < 0,0001). Nos pacientes, o TBSS mostrou as maiores alterações no giro temporal superior esquerdo (aumento de difusão axial; 423 mm3; p = 0,028), no lobo temporal esquerdo (aumento da difusão radial; 1132 mm3; p = 0,001), no uncus direito (aumento da difusão média; 254 mm3; p = 0,008) e no lobo temporal esquerdo (redução de anisotropia fracionada; volume de 17518 mm3; p < 0,001). Conclusão: As técnicas utilizadas mostraram resultados semelhantes. Entretanto, as análises se complementaram reforçando a significância dos achados. As alterações foram mais frequentemente observadas nos parâmetros de anisotropia fracionada e difusão radial indicando a necessidade do uso de múltiplos parâmetros de difusão para investigação de pacientes com ELMT. Foi possível observar um predomínio de alterações nas adjacências do lobo temporal mas alterações mais difusas também foram detectadas bem como maior comprometimento no lado esquerdo.
Objectives: Mesial temporal lobe epilepsy (MTLE) is the most common refractory epilepsy of adults. Hippocampal sclerosis (HS) is the most frequent structural abnormality associated with this disease. Quantitative techniques of diffusion analysis allow an in vivo mesoscopic analysis the epilepsy physiopathology. The objective of this investigation was to analyze the variation of the main diffusion parameters and explore differences between two methodologies of voxel-wise neuroimaging analysis, comparing a group of patients with MTLE to controls. Methods: Patients with MTLE and controls were selected. All patients and controls were underwent 3 Tesla magnetic resonance imaging. Diffusion parameters were obtained from the raw images. Based on the tensors, a customized template was created and images were transformed into standard space. Three comparisons for each parameter were performed: voxel-based morphometry (VBM), tract based spatial statistics (TBSS) and specific tract analysis. Results: 24 patients with MTLE and 36 controls were investigated. 10 patients presented with left HS, 11 with right and 3 bilateral with left predominance. VBM showed major abnormalities localized in the right parahippocampal gyrus (increased axial, radial and mean diffusivity; volumes 290, 758 and 595 mm3; p = 0.001, < 0.0001 and < 0.0001, respectively) and in the left temporal lobe (decreased fractional anisotropy; 719 mm3; p < 0.0001). TBSS showed major abnormalities in the left superior temporal gyrus (increased axial diffusivity; 423 mm3; p = 0.028), in the left temporal lobe (increased radial diffusivity; 1132 mm3; p = 0.001), in the right uncus (increased mean diffusivity; 254 mm3; p = 0.008) and in the left temporal lobe (decreased fractional anisotropy; volume 17518 mm3; p < 0.001). Conclusion: The two techniques used showed similar findings. The analyses were complementary, stressing the significance of the findings. The abnormalities were more frequently observed in fractional anisotropy and radial diffusivity indicating the need for several diffusion parameters in the investigation of patients with MTLE. We observed a predominance of abnormalities in the temporal lobe adjacencies but diffuse abnormalities and a major burden of the left side were also observed.
Objectives: Mesial temporal lobe epilepsy (MTLE) is the most common refractory epilepsy of adults. Hippocampal sclerosis (HS) is the most frequent structural abnormality associated with this disease. Quantitative techniques of diffusion analysis allow an in vivo mesoscopic analysis the epilepsy physiopathology. The objective of this investigation was to analyze the variation of the main diffusion parameters and explore differences between two methodologies of voxel-wise neuroimaging analysis, comparing a group of patients with MTLE to controls. Methods: Patients with MTLE and controls were selected. All patients and controls were underwent 3 Tesla magnetic resonance imaging. Diffusion parameters were obtained from the raw images. Based on the tensors, a customized template was created and images were transformed into standard space. Three comparisons for each parameter were performed: voxel-based morphometry (VBM), tract based spatial statistics (TBSS) and specific tract analysis. Results: 24 patients with MTLE and 36 controls were investigated. 10 patients presented with left HS, 11 with right and 3 bilateral with left predominance. VBM showed major abnormalities localized in the right parahippocampal gyrus (increased axial, radial and mean diffusivity; volumes 290, 758 and 595 mm3; p = 0.001, < 0.0001 and < 0.0001, respectively) and in the left temporal lobe (decreased fractional anisotropy; 719 mm3; p < 0.0001). TBSS showed major abnormalities in the left superior temporal gyrus (increased axial diffusivity; 423 mm3; p = 0.028), in the left temporal lobe (increased radial diffusivity; 1132 mm3; p = 0.001), in the right uncus (increased mean diffusivity; 254 mm3; p = 0.008) and in the left temporal lobe (decreased fractional anisotropy; volume 17518 mm3; p < 0.001). Conclusion: The two techniques used showed similar findings. The analyses were complementary, stressing the significance of the findings. The abnormalities were more frequently observed in fractional anisotropy and radial diffusivity indicating the need for several diffusion parameters in the investigation of patients with MTLE. We observed a predominance of abnormalities in the temporal lobe adjacencies but diffuse abnormalities and a major burden of the left side were also observed.
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Palavras-chave
Epilepsia de lobo temporal mesial, Ressonância magnética, Atrofia hipocampal, Mesial temporal lobe epilepsy, Magnetic resonance imaging