Efeito do movimento em MRI e implementação das técnicas de Gradient Moment Nulling e pré-saturação especial na redução de artefatos relacionados ao movimento. / Motion effects in magnetic resonance imaging and implementation of Gradient Moment Nulling and spatial presaturation for reducing motion related artifacts.

AUTOR(ES)
DATA DE PUBLICAÇÃO

1998

RESUMO

The purpose of this work was to analyze the effects of motion in conventional Magnetic Resonance Imaging (MRI), and to implement and optimize the Gradient Moment Nulling and Spatial Presaturation techniques, which can be used to minimize the motion related artifacts. Numerical simulations, were used to analyze the influence of the motion on the image and to understand the physics of the above techniques. In the Gradient Moment Nulling method, the compensation gradients amplitudes depends on the their positions in the sequence. To analyze this, some configurations for the sequence were proposed and the corresponding gradients amplitude were calculated. The best configuration for the sequence was chosen to minimize the gradients amplitudes. The sequences were tested experimentally and the results proved their efficacy in reducing the intravoxel dephasing and flow blique misregistration artifacts. Conventional sinc pulse were used in the implementation of the Spatial Presaturation technique and the limitation of this choice was analyzed experimentally and by nurnerical simulation. The reduction of the flow related enhancement and "aliasing" artifacts, was successfully achieved by the Spatial Presaturation technique.

ASSUNTO(S)

artefatos relacionados ao movimento imaging motion effects compensation compensação de efeitos do movimento motion related artifacts imagens

ACESSO AO ARTIGO

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