In vivo NMR diffusion spectroscopy: 31P application to phosphorus metabolites in muscle.

C. T. Moonen (1, 2, 3) , P. C. van Zijl , D. Le Bihan (4, 5) , D. Despres (1)

1 Department of Health and Human Services
2 Imagerie moléculaire et fonctionnelle: de la physiologie à la thérapie
3 Imagerie moléculaire et fonctionnelle: de la physiologie à la thérapie
4 NIH - National Institutes of Health [Bethesda, MD, USA]
5 NEUROSPIN - Service NEUROSPIN

Apparent diffusion coefficients (Da) of individual metabolites can be studied in vivo by diffusion NMR spectroscopy using an echo sequence sensitized to molecular motion. The methods are based on the echo attenuation due to phase dispersion resulting from incoherent displacement during the diffusion time. As the displacement of metabolites by diffusion in vivo can be affected by compartment size, temperature, adsorption processes, etc., the presented methods are potentially useful in studying such phenomena in vivo. Here, the methods are applied to phosphocreatine in the rat quadriceps muscle. It is demonstrated that the displacement of phosphocreatine resembles free diffusion for short diffusion times but becomes limited as a result of boundaries due to compartmentation for longer diffusion times. The limit of the displacement indicates an apparent average size of 44 microns of the compartment in the direction of the diffusion gradient. As the gradient was applied approximately parallel (angle less than 25 degrees) to the muscle fiber, this result indicates that phosphocreatine moves freely in the cytosol but is limited by the boundaries of the muscle cells. Error analyses are performed with regard to motion artifacts and gradient performance. The methods were tested extensively for distilled water and free metabolites.

Domaines: Imagerie

C. T. Moonen, P. C. van Zijl, D. Le Bihan, D. Despres. In vivo NMR diffusion spectroscopy: 31P application to phosphorus metabolites in muscle.. Magnetic Resonance in Medicine, 1990, 13 (3), pp.467-77. ⟨hal-00350078⟩