title: Brain tissue water comes in two pools: evidence from diffusion and R2' measurements with USPIOs in non human primates.
abstract: Diffusion-weighted MRI of non-human primates revealed that USPIO Bulk Magnetic Susceptibility (BMS) T2' effects of Ultrasmall Superparamagnetic Particles with Iron Oxide (USPIO) in the brain cannot be explained by a single compartment model, as diffusion and T2' effects appear coupled: Apparent Diffusion Coefficient (ADC) values depend on USPIO concentration and relaxivity effects of USPIO decrease with the b value. On the other hand, USPIO and diffusion effects could be well uncoupled using a model consisting in a fast and a slow diffusion pool with different relaxivities. Diffusion-weighting acts as a filter which emphasizes the contribution of the slow pool when increasing b values (apparent decrease in ADC and R2'). Those results have implications for human studies using BMS contrast agents, as well as BOLD and diffusion fMRI.
authors.affiliation: NeuroSpin, I²BM, CEA, Gif-sur-Yvette, France. denis.lebihan@gmail.com
authors.forename: D
authors.initials: D
authors.lastname: Le Bihan
authors.forename: O
authors.initials: O
authors.lastname: Joly
authors.forename: T
authors.initials: T
authors.lastname: Aso
authors.forename: L
authors.initials: L
authors.lastname: Uhrig
authors.forename: C
authors.initials: C
authors.lastname: Poupon
authors.forename: N
authors.initials: N
authors.lastname: Tani
authors.forename: H
authors.initials: H
authors.lastname: Iwamuro
authors.forename: S-I
authors.initials: SI
authors.lastname: Urayama
authors.forename: B
authors.initials: B
authors.lastname: Jarraya
mesh_terms: D000818:Animals; D001834:Body Water / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D003198:Computer Simulation; D003287:Contrast Media / Q000493:pharmacokinetics; D003911:Dextrans / Q000493:pharmacokinetics*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D008253:Macaca mulatta; D058185:Magnetite Nanoparticles; D008959:Models, Neurological; D014867:Water
chemical_list: D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; C097921:ferumoxtran-10; D014867:Water