Abstract #0379

Le Bihan D, Urayama S, Aso T, Hanakawa T, Fukuyama H

SynopsisA transient decrease of water diffusion has been reported during activation of visual cortex. We have investigated signal changes at different degrees of diffusion sensitization using a 2-compartment diffusion model. At 3T activation of visual cortex was detected in our 6 subjects though a diffusion-weighted signal increase, but the signal change increased with b value. This increase was well modeled by a swelling of the slow diffusion pool (+0.56%) and a shrinking of the fast diffusion pool (-0.44%), suggesting a shift of water from the fast to the slow diffusion pools. Although the nature of the pools is still unclear diffusion-sensitized MRI might provide direct and quantitative access to a physiological surrogate of cortical activation.