RESUMEN
OBJECTIVE: To explore the applicability of magnetic resonance diffusion tensor imaging (DTI) for diagnosis of pyramidal tract damage in rats. METHODS: Marmarou's model was set up, followed by DTI scanning at 3, 12, 24 and 72 h post trauma to acquire the dispersion parameter of bilateral pyramidal tracts. Moreover, axonal varicosities per square millimeter and the percentage of positive area of axons demonstrated by beta-amyloid precursor protein (beta-APP) immunostaining were obtained, as well as the mean density and sum density of neurofilament (NF) 68 immunostaining. RESULTS: Axial diffusivity (AD), fraction anisotropy (FA) and relative anisotropy (RA) in the pyramidal tract were significantly and continuously reduced and reached to the bottom at 72h post trauma (P < 0.05) in accord with the gradient of axonal damage verified by beta-APP and NF68 immunostaining. Furthermore, the changes of AD, FA and RA showed a significant negative correlation with the beta-APP immunohistochemical results. CONCLUSION: DTI has important value for early diagnosis in pyramidal tract damage.
Asunto(s)
Lesiones Encefálicas/diagnóstico , Encéfalo/patología , Imagen de Difusión por Resonancia Magnética/métodos , Tractos Piramidales/patología , Precursor de Proteína beta-Amiloide/metabolismo , Animales , Anisotropía , Axones/patología , Encéfalo/metabolismo , Lesiones Encefálicas/metabolismo , Lesiones Encefálicas/patología , Modelos Animales de Enfermedad , Procesamiento de Imagen Asistido por Computador , Masculino , Proteínas de Neurofilamentos/metabolismo , Tractos Piramidales/metabolismo , Ratas , Ratas Sprague-Dawley , Índice de Severidad de la Enfermedad , Factores de TiempoRESUMEN
Traumatic brain injury (TBI) is a highly complex multi-factorial disorder. Animal models of TBI are used to elucidate primary and secondary injury mechanisms and pathophysiological changes and to provide the diagnostic and therapeutical basis for TBI. The choices of animal models depend upon the research objectives. However, various animal models have limitations. The models only can duplicate the pivotal injury mechanisms or a certain important pathophysiological course. The characteristics of human TBI can not fully be reflected by using these models. In the review, animal models of traumatic brain injury are classified as dynamic direct brain injury, indirect dynamic brain injury and combined neuro-traumatic models. Several common models are described for consideration.