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Advisor(s)
Abstract(s)
Introdução – A ressonância magnética funcional (RMf) é hoje uma ferramenta
fundamental na investigação funcional do cérebro humano, quer em indivíduos saudáveis quer em doentes com patologias diversas. É uma técnica complexa que necessita de uma aplicação cuidada e rigorosa e uma compreensão dos mecanismos biofísicos, de modo a serem obtidos resultados fiáveis e com melhor aceitação clínica. O efeito BOLD
(Blood Oxygenation Level Dependent), que se baseia nas propriedades magnéticas da
hemoglobina, é o método mais utilizado para medir a atividade cerebral por RMf. Objetivos
– Otimizar um protocolo de RMf por efeito BOLD em voluntários saudáveis para mapeamento do córtex motor, de modo a que possa ser aplicado no futuro em doentes com patologias diversas. Metodologia – Foram estudados 34 voluntários saudáveis divididos
em 2 grupos de estudo: BOLD 1 e BOLD 2. Com vista à otimização, foram testados no subgrupo BOLD 1 diferentes paradigmas e no subgrupo BOLD 2 foi estudada a influência
do tempo de eco (TE). Para as várias condições foram comparados os volumes da
região ativada e os níveis de ativação obtidos. Resultados/Discussão – O córtex motor foi identificado em todos os voluntários estudados. Não foram detetadas diferenças estatisticamente significativas quando comparados os resultados obtidos com os diferentes parâmetros de aquisição. Conclusão – O protocolo foi otimizado tendo em conta o nível de conforto reportado pelos voluntários. Uma vez que se pretende aplicar este mesmo protocolo no estudo de doentes, este fator torna-se particularmente relevante.
ABSTRACT: Introduction – Functional magnetic resonance imaging (fMRI) is currently an essential tool for the study of human brain function, both in healthy volunteers and in patients suffering from multiple types of pathology. fMRI is a complex technique which needs to be applied in a careful and rigorous manner, requiring an understanding of its biophysical mechanisms so that reliable results with clinical acceptance can be obtained. The BOLD effect (Blood Oxygenation Level Dependent) is based on the magnetic properties of haemoglobin and it is the most used approach for measuring brain activity using MRI. Goals – To optimise a BOLD fMRI protocol on healthy volunteers for mapping the motor cortex, so that it can be applied to patients in the clinic. Methods – 34 healthy volunteers were divided into 2 study groups: BOLD 1 and BOLD 2. To optimise the acquisition, different paradigms were tested on sub-group BOLD 1. The influence of the echo time (TE) was studied on sub-group BOLD 2.The volume and activation level of the activated regions were compared under the different sets of conditions. Results/Discussion – It was possible to identify the motor cortex on all studied individuals. No significant statistical differences were detected when comparing the results obtained with the different acquisition parameters. Conclusion – The protocol was optimised taking into account the level of comfort reported by the volunteers. Given that the goal is to use this protocol to study patients, comfort is a particularly important factor.
ABSTRACT: Introduction – Functional magnetic resonance imaging (fMRI) is currently an essential tool for the study of human brain function, both in healthy volunteers and in patients suffering from multiple types of pathology. fMRI is a complex technique which needs to be applied in a careful and rigorous manner, requiring an understanding of its biophysical mechanisms so that reliable results with clinical acceptance can be obtained. The BOLD effect (Blood Oxygenation Level Dependent) is based on the magnetic properties of haemoglobin and it is the most used approach for measuring brain activity using MRI. Goals – To optimise a BOLD fMRI protocol on healthy volunteers for mapping the motor cortex, so that it can be applied to patients in the clinic. Methods – 34 healthy volunteers were divided into 2 study groups: BOLD 1 and BOLD 2. To optimise the acquisition, different paradigms were tested on sub-group BOLD 1. The influence of the echo time (TE) was studied on sub-group BOLD 2.The volume and activation level of the activated regions were compared under the different sets of conditions. Results/Discussion – It was possible to identify the motor cortex on all studied individuals. No significant statistical differences were detected when comparing the results obtained with the different acquisition parameters. Conclusion – The protocol was optimised taking into account the level of comfort reported by the volunteers. Given that the goal is to use this protocol to study patients, comfort is a particularly important factor.
Description
Keywords
Ressonância magnética funcional BOLD Córtex motor Tempo de eco RMf Motor cortex Functional magnetic resonance imaging fMRI Echo time
Citation
Nunes PR, Tecelão SR, Nunes RG. Ressonância magnética funcional: mapeamento do córtex motor através do efeito BOLD. Saúde & Tecnologia. 2014;(T2):e11-8.