Influencia de la difusión en imágenes de resonancia magnética de gases

Abstract

Diffusion influence on gas magnetic resonance imaging. Resolution of nuclear magnetic resonance (NMR) experiments with gasesemploying magnetic field gradients is greatly reduced due to their rapid diffusion. In this paper, we present a solution to this problem basedon a mixture of gases hyperpolarized with laser (LP) (3He or Xe) with other heavier and lighter buffer gases. In this way the diffusioncoefficient can be modified up to one order of magnitude. The signal of 1D images of 3He is described as a function of the concentration ina binary mixture of gases, and we show the existence of an optimum concentration for some image resolution parameters. Experimentsshow that with this concentration, the signal can gain an increase of up to 10 times the signal with pure 3He, in agreement with the theoryof non-restricted diffusion. Finally, the method is illustrated with 2D images of LP-3He mixed with several gases in a lung containingrestrictive cavities with different sizes.

Keywords

• gas MRI
• restricted diffusion
• lung
• buffer gas
• contrast
• hyperpolarized gases